Skip directly to search Skip directly to A to Z list Skip directly to page options Skip directly to site content
Scientific Data Documentation
National Hospital Discharge Survey, 1979-1996
DSN: CC36.NHDS7996.NEWBORN
     CC36.NHDS7996.NOT.NEWBORN
  
 
NATIONAL HOSPITAL DISCHARGE SURVEY, 1979-1996 DATA TAPE DOCUMENTATION  
This document is intended for users of the National Hospital Discharge Survey (NHDS)
multi-year data files containing all records for the 1979 to 1996 data years.  These data
files provide access to NHDS data for the years in which the 9th Revision of the
International Classification of Diseases, Clinical Modification (ICD-9-CM), has been
used for coding medical diagnoses and procedures.  However, important changes in the
survey methodology, as well as modifications of the coding system, have occurred during
the years spanned by these files.    
For those who are familiar with the single-year, public use data files for NHDS, it is
important to note several major differences between the multi-year files and the
single-year files.  First, unlike the annual, single-year files, there are two distinct multi-
year files, one containing records for newborn infants only, the other containing non-
newborn records.  Second, the single-year data files include several recodes of basic
variables which are not included on the multi-year files.  Third, to save space, all blank
fields which separate data elements on the single year files have been eliminated from the
multi-year files, resulting in a different data layout. 
NOTE: Separate files which contain information needed for Appendices D and E are
provided in LOTUS files on a diskette accompanying this documentation. 
       
I.  DESCRIPTION OF THE NATIONAL HOSPITAL DISCHARGE SURVEY
  
INTRODUCTION.  The National Hospital Discharge Survey (NHDS) has been
  conducted continuously by the National Center for Health Statistics (NCHS) since 1965. 
  It provides data on inpatient utilization of short-stay, non-Federal hospitals in the United
  States.  The NHDS abstracts both demographic and medical information from the face
  sheets of the medical records of inpatients selected from a national sample of hospitals. 
  Based on this information, national and regional estimates of characteristics of patients,
  lengths of stay, diagnoses, and surgical and nonsurgical procedures in hospitals of various
  bed sizes and types of ownership are produced.  The survey design, sampling, and
  estimation procedures were planned to produce calendar year estimates.    
  The NHDS utilizes a stratified, multi-stage probability design.  The original sample,
  drawn in 1965 and followed through 1987, was based on a two-stage sampling plan.  A
  new sample was drawn in 1988, when a three-stage sampling plan was implemented, and
  several data collection and estimation procedures were revised.  The redesign of the
  survey is important, especially for those conducting trend analyses.  That is, because the
  new survey differs from the original one in sample design, data collection, and estimation
  procedures, some of the differences between NHDS statistics based on the 1965-87
  sample and statistics based on the sample drawn in 1988 may due to the survey redesign
  rather than actual changes in hospital utilization.    
  Since 1979, the International Classification of Diseases, 9th Revision, Clinical
  Modification, (ICD-9-CM), has been used for classifying diagnoses and procedures in the
  NHDS.  However, beginning in 1986, the ICD-9-CM has been modified annually. These
  modifications become effective in October of each year and are published in an
  Addendum.  Users of the NHDS who wish to conduct trend analyses or other multiple
  year studies must take into account the ICD-9-CM Addenda.  Appendix B contains the
  changes for 1986 through 1995.   
  For a general description of the survey design and data collection procedures, see below. 
  For more detailed information on technical aspects of the survey, see Reference 1. 
  Publications based on the data collected in each survey year can be obtained from the
  Government Printing Office. Rates in these publications may differ slightly from rates
  which are calculated using the population estimates provided here because the population
  estimates accompanying this dataset are based on the 1990 decennial census.  
HISTORY.  In 1962, the NCHS began exploring possibilities for conducting a survey to
  provide information on the utilization of the Nation's hospitals and on the nature and
  treatment of illness among the hospitalized population.  A national advisory group was
  established, and NCHS undertook planning discussions with other officials of the Public
  Health Service.  Hospitalization material from the Survey Research Center of the
  University of Michigan, the American Hospital Association, and the Professional
  Activities Study was examined and evaluated.  In 1963, a study by the School of Public
  Health of the University of Pittsburgh under contract to the NCHS demonstrated the
  feasibility of an NHDS type of program.  An additional pilot study using enumerators
  from the Bureau of the Census was conducted in late 1964 and confirmed the University
  of Pittsburgh's findings.  Finally, with advice and support from the American Hospital
  Association, the American Medical Association, individual experts, other professional
  groups, and officials of the U.S. Public Health Service, the NCHS initiated the National
  Hospital Discharge Survey in 1964.
  
SOURCE OF THE DATA.  The National Hospital Discharge Survey (NHDS) covers
  discharges from noninstitutional hospitals, exclusive of Federal, military, and Veterans
  Administration hospitals, located in the 50 States and the District of Columbia.  Only
  short-stay hospitals (those with an average length of stay for all patients of less than 30
  days) or those whose specialty is general (medical or surgical) or children's general are
  included in the survey.  These hospitals must also have six or more beds staffed for
  patient use.  These criteria, used since the survey redesign in 1988, differ slightly from
  those used under the old design.  Prior to 1988, hospitals with an average length of stay of
  30 days or more were excluded, regardless of specialty.  However, the term "short-stay"
  continues to be used because 98 percent of the hospitals in the NHDS universe fall into
  this category.   
  The original universe for the survey consisted of 6,965 short-stay hospitals contained in
  the 1963 National Master Facility Inventory of Hospitals.  This list was updated
  periodically from lists of hospitals provided by the American Hospital Association. 
  When the survey was redesigned in 1988, the NHDS sampling frame consisted of
  hospitals that were listed in the April 1987 SMG Hospital Market Tape (Reference 2),
  met the above criteria, and began accepting patients by August 1987.  Table 1 shows the
  number of hospitals in the NHDS universe and sample, as well as the approximate
  number of sampled abstracts and estimated number of discharges, for each year from
  1979 to 1996.  Beginning in 1984, data on the universe of short-stay non-Federal
  hospitals were obtained from the American Hospital Association, instead of the Master
  Facility Inventory of Hospitals.
  
SAMPLING DESIGN.  The purpose of the NHDS redesign in 1988 was to provide
  geographic comparability with other surveys conducted by the NCHS; to update the
  sample of hospitals; and to use data already available in automated systems.  While the
  redesign added some complexity to the sampling plan of the NHDS, the old and new
  designs remain quite similar.  Under both designs, all hospitals with 1,000 or more beds
  were selected with certainty.  In the redesigned NHDS sample, all hospitals with 40,000
  or more discharges annually were also certainty hospitals.  In both designs, discharges
  were selected within hospitals according to a systematic sampling procedure.  
TABLE 1.  Number of  Hospitals in Universe and Sample, Participation and Respondent Counts,
          Approximate Total Number of Sampled Discharge Abstracts, and Estimated Number of 
          Patients Discharged, NATIONAL HOSPITAL DISCHARGE SURVEY, 1979-1996 

DATA YEAR

NUMBER OF HOSPITALS IN UNIVERSE

NUMBER OF HOSPITALS IN SAMPLE

NUMBER OF OUT-OF-SCOPE HOSPITALS

NUMBER OF REFUSAL HOSPITALS

NUMBER OF RESPONDING HOSPITALS

APPROXIMATE NUMBER OF SAMPLED ABSTRACTS

ESTIMATED NUMBER OF DISCHARGES (in thousands)

[includes newborn infant records]

[excludes newborn infants]

1979

8,017

544

48

80

416

215,000

36,747

1980

8,017

544

52

72

420

224,000

37,832

1981

8,080

550

51

71

428

227,000

38,543

1982

8,080

550

53

71

426

214,000

38,594

1983

8,130

553

57

78

418

206,000

38,784

1984

6,023

553

60

86

407

192,000

37,162

1985

6,007

558

62

82

414

195,000

35,057

1986

6,007

558

65

75

418

193,000

34,255

1987

6,007

558

66

92

400

181,000

33,387

1988

6,400

542

11

109

422

250,000

31,146

1989

6,400

542

16

118

408

233,000

30,947

1990

6,400

542

23

45

474

266,000

30,788

1991

6,250

528

7

37

484

274,000

31,098

1992

6,250

528

14

20

494

274,000

30,951

1993

6,250

528

15

47

466

235,000

30,825

1994

6,337

525

13

34

478

277,000

30,843

1995

6,337

525

17

42

466

263,000

30,722

1996

6,337

525

18

27

480

282,000

30,545

From 1984 to 1987, data on the universe of short-stay, non-Federal hospitals was obtained from the
American Hospital Association, instead of the Master Facility Inventory of Hospitals.

Beginning in 1988, the sampling frame for hospitals has been the SMG Hospital Market Database

(References 2-4).

From 1984 to 1987, data on the universe of short-stay, non-Federal hospitals 
was obtained from the American Hospital Association, instead of the Master 
Facility Inventory of Hospitals.  Beginning in 1988, the sampling frame for 
hospitals has been the SMG Hospital Market Database (References 2-4).
However, the old and new designs differ in how noncertainty hospitals were selected.  
In the former, a two-stage sample was used, and in the latter, a three-stage plan was
implemented. Under the old design, the first-stage sampling units were hospitals, which
were selected within 24 bedsize-by-region strata, controlling for type of ownership and
Census geographic division.  At the second stage, discharges within hospitals were
selected by a systematic random sampling technique, using a sampling rate such that the
overall probability of selecting a discharge was approximately the same in each
hospital-size class.  In the new design, 112 PSU's from the 1985-94 National Health
Interview Survey sample were selected as first-stage sampling units. Hospitals within
PSU's were then selected at the second stage.  Strata at this stage were defined by
geographic region, PSU size, abstracting service status,  PSU, and hospital specialty-size
groups.  Within strata, hospitals were selected with probabilities proportional to their
annual number of discharges.  At the third stage, a sample of discharges was selected by a
systematic random sampling technique.  The sampling rate was determined by the
hospital's sampling stratum and the type of data collection  system (manual or automated)
used.    
Note again that these changes in the design of the survey may affect trend data.  That is,
some observed differences between NHDS statistics based on the 1965-87 sample and
those based on the redesigned sample may be due to updating the sample and revising
data collection and estimation procedures rather than actual changes in hospital
utilization.  A report comparing selected estimates obtained from the old and the new
survey designs has also been published (Reference 5).  
  
DATA COLLECTION PROCEDURES.  Originally, all data collection for NHDS was
  conducted manually within the hospital, either by hospital personnel or by Bureau of
  Census staff under contract with NCHS.  Currently, approximately 62 percent of the
  responding hospitals utilize the manual system of sample selection and data abstraction. 
  Of the hospitals using this system in 1996, about 34 percent had the work performed by
  their own medical records staff.  In the remaining hospitals using the manual system,
  personnel of the U.S. Bureau of the Census did the work on behalf of NCHS.  The
  completed forms, along with sample selection control sheets, were forwarded to NCHS
  for coding, editing, and weighting.    
  Beginning in 1985, data from some hospitals was obtained from commercial abstracting
  services, state computerized data systems, or a hospital's own computer system. 
  Computer tapes from these sources contained machine-readable medical record data from
  which records were systematically sampled by NCHS.  In 1996, this method was used for
  about 38 percent of the respondent hospitals. 
  
THE UNIFORM HOSPITAL DISCHARGE DATA SET  (UHDDS).  Starting with 1979
  data, the NHDS has followed guidelines of the Uniform Hospital Discharge Data Set
  (UHDDS) within the confines of its contractual agreement with participating hospitals. 
  The UHDDS is a uniformly defined, minimum data set  (Reference 6).  Items for the data
  set were selected on the basis of their usefulness to a broad range of organizations and
  agencies requiring hospital information, uniformity of definition, and general availability
  from medical records and abstract services.    
  Both the medical abstract form used in manual data collection and the automated data
  contain items relating to the personal characteristics of the patient, including birth date or
  age, sex, race, and marital status; administrative information, including admission and
  discharge dates, discharge status, and medical record number; and medical information,
  including up to seven diagnoses and up to four surgical or nonsurgical procedures.  Since
  1977,  patient zip code, expected source of payment, and dates of surgery have also been
  collected.  The medical record number, date of birth, and patient zip code are confidential
  information and are not available to the public.  The medical abstract form (HDS-1) is
  updated periodically.
  
MEDICAL CODING AND EDIT.  The medical information that was recorded manually
  on the sampled patients' abstracts was coded centrally by NCHS staff, using the
  International Classification of Diseases, 9th Revision, Clinical Modification, or
  ICD-9-CM (Reference 7).  A maximum of seven diagnostic codes was assigned for each
  sampled abstract; in addition, if the medical information included surgical or nonsurgical
  procedures, a maximum of four codes for these procedures was assigned.  Since 1991, all
  of the diagnostic and procedure codes in the ICD-9-CM have been utilized.  However, for
  the years 1979 to 1990, some procedure codes were not utilized and so it is not possible
  to produce estimates for those codes.  Appendix C contains a listing of the procedures not
  coded and the year the code was first used.  It is important to note that the ICD-9-CM
  serves as a basis for classifying morbidity information on medical records, and as a tool
  for generating basic health statistics.  As it is used in the NHDS, it is not intended to
  provide a complete clinical picture of a patient.    
  NHDS usually presents diagnoses and procedures in the order they are listed on the
  abstract form or obtained from abstract services, however, there are exceptions.  For
  women discharged after a delivery, a code of V27 from the supplemental classifications
  was entered as the first-listed code, with a code designating either normal or abnormal
  delivery in the second-listed position.  In another exception, a decision was made to
  reorder some acute myocardial infarction (AMI) diagnoses.  If an acute myocardial
  infarction was listed with other circulatory diagnoses and was other than the first entry, it
  was reordered to the first position.  If a code from Chapter 16 (Symptoms, Signs, and
  Ill-Defined Conditions), appeared as a first-listed code and a diagnosis appeared as a
  secondary code, the diagnosis code was moved to the first position and the symptom code
  was moved back.    
  Following conversion of the information on the medical abstracts to computer tape and
  combining it with the automated data tapes, a final medical edit was accomplished by
  computer inspection and by a manual review of rejected records.  Priority was given to
  medical information in the editing.
  
MEASUREMENT ERRORS.  As in any survey, results were subject to nonsampling or
  measurement errors, which included errors due to hospital nonresponse, missing
  abstracts, information incompletely or inaccurately recorded on abstract forms, and
  processing errors.  In general, approximately one percent of the discharge records failed
  to include the age or sex of the patient.  If the hospital record did not state the age or sex
  of the patient, it was imputed by assigning the patient an age or sex consistent with the
  age or sex of other sampled patients with the same diagnostic code.  Beginning in 1996,
  this imputation was designed to maintain the known distribution of the age or sex
  variable.  If the dates of admission or discharge were not given, and if they could not be
  obtained from the monthly sample listing sheet transmitted by the sample hospital, a
  length of stay was imputed by assigning the patient a stay characteristic of the stays of
  other patients of the same age.  For records where the length of stay and the discharge
  month were known, a discharge day of the 20th of the month was assigned to the record,
  and the admission date was computed based on the given length of stay.  Other edit and
  imputation procedures may have been applied to data received in automated form.
  
SAMPLING ERRORS AND ROUNDING OF NUMBERS.  The standard error is
  primarily a measure of sampling variability that occurs by chance because only a sample
  rather than the entire universe is surveyed.  The relative standard error of an estimate
  (RSE) is obtained by dividing the standard error by the estimate itself.  When the
  resulting value is multiplied by 100, the relative standard error is expressed as a percent
  of the estimate.  The RSE is used as guide to the reliability of the estimate (see
  Presentation of Estimates below).    
  Since 1988, estimates of sampling variability have been calculated with SESUDAAN or
  SUDAAN software, which computes standard errors by using a first-order Taylor series
  approximation of the deviation of estimates from their expected values.  A description of
  the software and the approach it uses was published by Shah (Reference 8).  Before 1988,
  standard error estimates were produced using a computerized routine based on a
  rigorously unbiased algebraic estimator of the variance.     
  To obtain standard errors that would be applicable for a wide variety of statistics and that
  could be prepared at a moderate cost, numerous variances were calculated and a best fit
  formula was derived.  This formula, which is based on an empirically determined
  relationship between the size of an estimate, X, and its relative variance, was used to
  produce generalized variance curves. These curves provide approximations to the relative
  standard errors that are applicable to estimates of discharges, first- or all-listed diagnoses,
  all-listed procedures, and days of care, either aggregated or disaggregated by selected
  patient or hospital characteristics.   
  For the years 1979 through 1987, curves are represented in tables containing estimates of
  different sizes and their approximate relative standard errors.  For the years 1988 through
  1996, tables contain parameter values which can be substituted in a mathematical formula
  (described in Appendix D) to produce approximate relative standard errors.  Instructions
  on how to use the tables and/or the parameter values are also given in Appendix D.   
  
PRESENTATION OF ESTIMATES.  Based on consideration of the complex sample
  design of the NHDS, the following guidelines are recommended for using the 
  NHDS estimates:       
  If the sample size is less than 30, the value of the estimate is 
  not reported.   

  If the sample size is 30-59, the value of the estimate is reported 
  but should not be assumed reliable.     

  If the sample size is 60 or more and the relative standard error is 
  less than 30 percent, the estimate may be reported.      

  If the sample size is 60 or more but the relative standard error is 
  over 30 percent, the estimatemay be reported but should not be assumed 
  reliable.
  
POPULATION ESTIMATES.  Hospital utilization rates are computed using U.S. Census
  Bureau population estimates as denominators.  Before 1981, estimates of rates of
  discharges and days of care which appeared in published reports from NCHS were
  calculated using estimates of the civilian noninstitutional population (CNP).  However,
  beginning in 1981, estimates of the civilian resident population (CRP) were used to
  calculate hospital utilization rates.  The CRP was determined to be more appropriate
  because persons in institutions, for example nursing home patients, are hospitalized when
  necessary.  A report has been published which discusses differences in discharge rates
  based on the different denominators (Reference 9).   
  Files containing estimates of the civilian resident population as of July 1 of each year
  from 1979 to 1996 are provided with this documentation.   The estimates for 1980-1996
  have been adjusted based on the 1990 decennial census, and the 1979 estimates were
  adjusted based on the 1980 census.  Therefore, any rates calculated with these estimates
  may differ slightly from those which appear in published NCHS reports or those
  calculated from population estimates disseminated with the NHDS single-year data tape
  documentation.  
  
CAUTION ABOUT MONTHLY AND SEASONAL ESTIMATES.  An important difference between the
  old and new designs is the method used to adjust for nonresponse.  The result
  of this difference is that monthly and seasonal estimates under the new design
  may be skewed.  While the effect is believed to be small, it is recommended that partial
  year estimates not be produced for 1988 and later years. The reasons for this are
  explained below.  
  In the old design, weights for responding hospitals were adjusted each month to account
  for hospitals that did not respond for that month.  In the new design, the type of
  nonresponse adjustment applied depended on whether the hospital was considered a
  nonrespondent or partial respondent.  A nonresponding hospital was one which failed to
  provide at least half of the expected number of discharges for at least half of the months
  for which it was inscope.  In this case, weights of discharges from hospitals similar to the
  nonresponding hospital were inflated to account for discharges of the nonrespondent
  hospital.  However, this adjustment was performed just once, after the close out of the
  survey for the year, instead of monthly as before.    
  For partially responding hospitals, one or both of two adjustments were made.  If the
  hospital provided at least half, but not all, of the expected number of abstracts for a given
  month, the weights of the abstracts actually collected for that month were inflated to
  account for the missing abstracts.  If fewer than half of the expected number of abstracts
  were provided, the weights of the abstracts provided were inflated by a factor of two, then
  another adjustment was made to account for the excess nonresponse.  In the second
  adjustment, the weights of the discharges in the hospital's respondent months were
  inflated by ratios that varied by category of first-listed ICD-9-CM diagnostic code.  This
  adjustment ratio was based on the hospital's month(s) of nonresponse and the
  month-by-month distributions of first-listed diagnostic groups among discharges from
  hospitals which responded for all twelve months.  The ratio accounts for the seasonality
  in the occurrence of the first-listed diagnostic groups for annual statistics, but not for
  partial year estimates.  As a result, monthly and seasonal estimates may be skewed. 
  While the effect is believed to be small, it is recommended that partial year estimates not
  be produced.  In the 1996 NHDS, 76 percent of the 480 responding hospitals provided
  data for all twelve months, and 95 percent provided at least 9 months of data. 
  
HOW TO USE THE DATA FILE.  The NHDS records contain weights to allow inflation
  to national or regional estimates.  The weight for each record is found in tape location
  21-25.  To produce an estimate of the number of discharges, the weights for the desired
  records must be summed.  To produce an estimate for number of days of care, the weight
  must be multiplied by the days of care (tape location 13-16) and these products summed. 
  Estimates apply to the calendar year (January-December).   Appendix F contains
  frequencies for selected descriptive variables on the data tape.  These may be used as a
  cross-check when processing the data on the user's system.
  
QUESTIONS.  Questions concerning the data file should be directed to Maria Owings,
  Ph.D., Hospital Care Statistics Branch, Division of Health Care Statistics, National
  Center for Health Statistics, Presidential Building, Room 956, 6525 Belcrest Road,
  Hyattsville, Maryland  20782, (301)-436-7125.
REFERENCES
  
1. National Center for Health Statistics:  Development of the design of the NCHS
   Hospital Discharge Survey, by W. R. Simmons.  Vital and Health Statistics.  PHS Pub.
   No. 1000, Series 2-No. 39.  Public Health Service.  Washington.  U.S. Government
   Printing Office, Sept. 1970.  
2. SMG Marketing Group, Inc.  Hospital Market Database.  Chicago: Healthcare
   Information Specialists.  1987.  
3. SMG Marketing Group, Inc.  Hospital Market Database.  Chicago: Healthcare
   Information Specialists.  April 1991.  
4. SMG Marketing Group, Inc.  Hospital Market Database.  Chicago: Healthcare
   Information Specialists.  April 1994.  
5. Estimates from Two Survey Designs:  National Hospital Discharge Survey, by 
   B. Haupt and L. J. Kozak, Vital and Health Statistics.  DHHS Pub. No. (PHS) 
   92-1772, Series 13, No.111. Public Health Service. Washington. U. S. Government 
   Printing Office, May 1992.  
6. Office of the Secretary,  Department of Health and Human Services:  Health
   Information Policy Council: 1984 Revision of the Uniform Hospital Discharge 
   Data Set.  Federal Register,Volume 50, No. 147. July 31, 1985.  
7. National Center for Health Statistics:  International Classification of Diseases, 
   9th Revision, Clinical Modification.  DHHS Pub. No. (PHS) 80-1260.  Public Health 
   Service.  Washington. U.S. Government Printing Office, Sept. 1980.  
8. Shah, B.V. 1981.  SESUDAAN:  Standard Errors Program for Computing of
   Standardized Rates from Sample Survey Data.  Research Triangle Institute. 
   Research Triangle Park, N.C.  
9. Adjustment of Hospital Utilization Rates--United States, 1965-80, by R. Pokras 
   and L.J. Kozak.  Vital and Health Statistics.  DHHS Pub. No. (PHS) 85-1742, 
   Series 13, No.81.  Public Health Service. Washington. U. S. Government Printing 
   Office, Dec. 1984.
II.  TECHNICAL DESCRIPTION OF TAPE
  
  Data Set Name (Non-Newborns)----------------BG00.NHDS7996.NOT.NEWBORN
  Data Set Name (Newborns)------------------------BG00.NHDS7996.NEWBORN
  Number of Cartridges  (Non-Newborns)--------------------------------1
  Number of Cartridges  (Newborns)------------------------------------1
  Number of Recording Tracks ----------------------------------------18
  Density (bpi)-----------------------------------------------------38k
  Language-------------------------------------------------------EBCDIC
  Parity------------------------------------------------------------Odd 
  Record Length------------------------------------------------------83 
  Block Size-----------------------------------------------------31,200
  Number of Records (Non-Newborns)----------------------------3,778,368 
  Number of Records (Newborns)----------------------------------422,512
  
III.  TAPE RECORD FORMAT
 
  This section provides detailed information for each sampled record on the file, with a
  description of the coding of each item included on the record.  Data elements are arranged
  sequentially according to their physical location on the record.  Unless otherwise stated in
  the Item Description, the data are derived from the abstract form or from automated
  sources.  The SMG Hospital Market Tape and the hospital interview are alternate sources
  of data; some other items are computer generated.  NATIONAL HOSPITAL DISCHARGE SURVEY, Multi-year Data File
LAYOUT AND CODING OF DATA ITEMS
  
VARIABLE POSITION COMMENTS
Survey Year 1-2 2-digit value for each data year
(i.e. 79 to 96). NOTE: Century designation is located in col. 81-82.
Newborn Flag 3 Flag for NEWBORN records:

1 = Newborn
2 = Non-Newborn

Units for Age 4 1 = Years
2 = Months
3 = Days
Age 5-6 If Units = Years: 00-99
If Units = Months: 01-11
If Units = Days: 00-31

NOTE: Ages 100 years and over were recoded to 99 years.

Sex 7 1 = Male
2 = Female
Race 8 1 = White
2 = Black
3 = American Indian/Eskimo
4 = Asian/Pacific Islander
5 = Other
9 = Race Not Stated

NOTE: For 1979, only codes 1, 2, and 9 are available.

Marital Status 9 1 = Married
2 = Single
3 = Widowed
4 = Divorced
5 = Separated
6 = Unknown
9 = Not Stated
Month of Admission 10-11 01 = January . . . 12 = December
99 = Missing (1996 only)
Discharge Status 12 1 = Routine/Discharged Home
2 = Left Against Medical Advice
3 = Discharged/Transferred to Short
      Term Facility (In 1979 and 1980,
      D/T to Unspecified Facility)
4 = Discharged/Transferred to Long
      Term Facility (In 1979 and 1980,
      D/T to Organized Home Care)
5 = Alive, Disposition Not Stated
      (Option not coded in 1979 and 1980)
6 = Dead
9 = Disposition Not Stated
Days of Care 13-16 Use to calculate patient days of care;

Values of zero generated by the computer from admission and discharge dates were changed to one.

(Discharges for which dates of admission and discharge are the same are identified by the variable, Length of Stay Flag)

Length of Stay Flag 17 0 = Less than 1 day (admitted and
      discharged on the same day)
1 = 1 day or more
Geographic Region 18 1 = NorthEast
2 = MidWest
3 = South
4 = West
Number of Beds,

Interview Recode

19 1 = 6-99
2 = 100-199
3 = 200-299
4 = 300-499
5 = 500 and over
Hospital Ownership 20 1 = Proprietary
2 = Government
3 = Not for Profit
Analysis Weight 21-25 Use to obtain weighted estimates
Principal Expected Source of Payment 26 0 = No Charge
1 = Worker’s Compensation
2 = Medicare
3 = Medicaid
4 = Other Government Payments
5 = Blue Cross
6 = Other Private/Commercial Ins.
7 = Self-Pay
8 = Other
9 = Payment Not Stated
Secondary Expected Source of Payment 27 Same coding as principal, above
Diagnosis Code #1 28-32 ICD-9-CM Diagnosis Code #1 *
Diagnosis Code #2 33-37 ICD-9-CM Diagnosis Code #2 *
Diagnosis Code #3 38-42 ICD-9-CM Diagnosis Code #3 *
Diagnosis Code #4 43-47 ICD-9-CM Diagnosis Code #4 *
Diagnosis Code #5 48-52 ICD-9-CM Diagnosis Code #5 *
Diagnosis Code #6 53-57 ICD-9-CM Diagnosis Code #6 *
Diagnosis Code #7 58-62 ICD-9-CM Diagnosis Code #7 *
Procedure Code #1 63-66 ICD-9-CM Procedure Code #1 *
Procedure Code #2 67-70 ICD-9-CM Procedure Code #2 *
Procedure Code #3 71-74 ICD-9-CM Procedure Code #3 *
Procedure Code #4 75-78 ICD-9-CM Procedure Code #4 *
Discharge Month 79-80 01 = January . . . 12 = December
First 2 digits of DataYear 81-82 19 = 1900's

Starting in data year 2000, the value 20 will be assigned.

Partial/Full Responding Hospital 83 0 = Hospital responded for 12 months
1 = Hospital is partial respondent
     (i.e. Hospital responded for fewer than 12
       months)
  
  
APPENDIX A  
DEFINITION OF TERMS
  
  Terms Relating to Hospitals and Hospitalization
  
  HOSPITALS-Short-stay hospitals or hospitals whose specialty is general (medical or
  surgical), or children's general.  Hospitals must have 6 or more beds staffed for patient
  use.  Federal hospitals and hospital units of institutions are not included.
  
  TYPE OF OWNERSHIP OF HOSPITAL-The type of organization that controls and
  operates the hospital.  Hospitals are grouped as:     
            
  NOT FOR PROFIT - Hospitals operated by a church or another not for
  profit organization.     
  
  GOVERNMENT - Hospitals operated by State and local government.     
 
  PROPRIETARY - Hospitals operated by individuals, partnerships, or
  corporations for profit.
  
  PATIENT-A person who is formally admitted to the inpatient service of a short-stay
  hospital for observation, care, diagnosis, or treatment, or by birth. 
  
  DISCHARGE-The formal release of a patient by a hospital; i.e. the termination of a
  period of hospitalization by death or by disposition to place of residence, nursing home,
  or another hospital.  The terms "discharges" and "patients discharged" are used
  synonymously.
  
  DISCHARGE RATE-The ratio of the number of hospital discharges during the year to
  the number of persons in the civilian population on July 1 of that year.
  
  DAYS OF CARE-The total number of patient days accumulated at time of discharge by
  patients discharged from short-stay hospitals during a year.  A stay of less than 1 day
  (patient admission and discharge on the same day) is counted as 1 day in the summation
  of total days of care.  For patients admitted and discharged on different days, the number
  of days of care is computed by counting all days from (and including) the date of
  admission to (but not including) the date of discharge.
  
  RATE OF DAYS OF CARE-The ratio of the number of patient days accumulated at time
  of discharge to the number of persons in the civilian population on July 1 of that year.
  
  AVERAGE LENGTH OF STAY-The total number of days of care accumulated at time
  of discharge by patients discharged during the year, divided by the number of patients
  discharged. 
  
  Terms Relating to Diagnoses and Procedures
  
  DISCHARGE DIAGNOSES-One or more diseases or injuries (or some factor that
  influences health status and contact with health services that is not itself a current illness
  or injury) listed by the attending physician on the medical record of a patient.  In the
  NHDS, discharge (or final) diagnoses listed on the face sheet (summary sheet) of the
  medical record are transcribed in the order listed.  Each sample discharge is assigned a
  maximum of seven, five-digit codes according to ICD-9-CM (see Reference 5).
  
  PRINCIPAL DIAGNOSIS-The condition established after study to be chiefly responsible
  for occasioning the admission of the patient to the hospital for care.
  
  FIRST-LISTED DIAGNOSIS-The coded diagnosis identified as the principal diagnosis
  or listed first on the face sheet of the medical record if the principal diagnosis cannot be
  identified. The number of first-listed diagnoses is equivalent to the number of discharges.
  
  PROCEDURE-One or more surgical or nonsurgical operations, procedures, or special
  treatments listed by the physician on the medical record.  In the NHDS, all terms listed on
  the face sheet (summary sheet) of the medical record under the caption "operation",
  "operative procedures", "operations and/or special treatment", and the like are transcribed
  in the order listed.  A maximum of four procedures are coded.     Historically, procedures
  were categorized into four classes according to UHDDS guidelines.  Classes 1-3
  consisted of significant procedures, i.e., those that carried an operative or anesthetic risk
  or required highly trained personnel, special facilities, or special equipment.  Class 4
  procedures were not considered significant; therefore, reporting was optional.  From 1979
  through the middle of 1983, only three Class 4  procedures were coded for the NHDS: 
  circumcision, episiotomy, and removal of intrauterine contraceptive device.  Since the
  last half of 1983, additional codes were added, until 1991, when all procedures were
  coded.  
  
  RATE OF PROCEDURES-The ratio of the number of all-listed procedures during a year
  to the number of persons in the civilian population on July 1 of that year.
  
  Demographic Terms
  
  AGE-Refers to the age of the patient on the birthday prior to admission to the hospital
  inpatient service.
  
  POPULATION-Civilian population is the resident population excluding members of the
  Armed Forces.
  
  GEOGRAPHIC REGION-Hospitals are classified by location in one of the four
  geographic regions of the United States corresponding to those used by the U.S. Bureau
  of the Census:
  
  NORTHEAST       MIDWEST        SOUTH                 WEST
  Maine           Michigan       Delaware              Montana
  New Hampshire   Ohio           Maryland              Idaho
  Vermont         Illinois       District of Columbia  Wyoming
  Massachusetts   Indiana        Virginia              Colorado
  Rhode Island    Wisconsin      West Virginia         New Mexico
  Connecticut     Minnesota      North Carolina        Arizona
  New York        Iowa           South Carolina        Utah
  New Jersey      Missouri       Georgia               Nevada
  Pennsylvania    North Dakota   Florida               Washington
                  South Dakota   Kentucky              Oregon
                  Nebraska       Tennessee             California
                  Kansas         Alabama               Hawaii
                                 Mississippi           Alaska
                                 Arkansas
                                 Louisiana
                                 Oklahoma
                                 Texas

 

APPENDIX B  
  The International Classification of Diseases, 9th Revision, Clinical Modification has
  been used for coding medical data in the NHDS since 1979.  However, since 1986, the
  classification system has undergone annual updating.  The changes, which include
  assignment of new diagnostic and procedure codes, fourth and fifth digit expansion of
  codes, as well as code deletions, have been released for the years 1986 through 1996. 
  These changes are published in an Addendum and become effective October 1 of the
  calendar year. Addenda are developed by the ICD-9-CM Coordination and Maintenance
  Committee and approved by the Director of NCHS and the Administrator of the Health
  Care Financing Administration.    
  It is important to recognize that, for the year in which a code undergoes revision,
  estimates for both the original and the revised code are not accurate, since each code was
  used for only part of the year.  Therefore, for codes which are revised in a given year, it is
  advisable to use data for the year following the revision to produce an estimate. However,
  for the 1992 through 1996 data years, any codes assigned which were consistent with the
  October Addendum of that year were changed back to their previous codes in order to
  avoid the problem of partial year estimates being mistaken for full year estimates.   
  In order to assist users in data retrieval, a conversion table is provided that shows for each
  new code, its date of introduction and the previously assigned code equivalent, which had
  been used for reporting the selected diagnosis or procedure prior to issuance of the new
  code.   This table shows coding changes up to October 1995.    
DIAGNOSIS CODES
  
DIAGNOSIS CODES

Effective

Current code(s) assignment

October 1

Previous code(s) assignment
005.81

1995

005.8
005.89

1995

005.8
008.00-008.09

1992

008.0
008.43-008.47

1992

008.49
008.61-008.69

1992

008.6
041.00-041.09

1992

041.0
041.10-041.19

1992

041.1
041.81-041.89

1992

041.8
041.86

1995

041.84
042

1994

042.0-042.2,042.9,043.0-043.3,
043.9,044.0,044.9
042.0-042.9

1986

279.19
043.0-043.9

1986

279.19
044.0-044.9

1986

279.19
070.20-070.21

1991

070.2
070.22

1994

070.20
070.23

1994

070.21
070.30-070.31

1991

070.3
070.32

1994

070.30
070.33

1994

070.31
070.41-070.49

1991

070.4
070.44

1994

070.41
070.51-070.59

1991

070.5
070.54

1994

070.51
077.98-077.99

1993

077.9
078.10-078.11,078.19

1993

078.1
078.88

1993

078.89
079.4

1993

079.8
079.50-079.53,079.59

1993

079.8
079.81

1995

079.89
079.88-079.89

1993

079.8
079.98-079.99

1993

079.9
088.81,088.89

1989

088.8
088.82

1993

088.89
099.40-099.49

1992

099.4
099.50-099.59

1992

078.89
112.84-112.85

1992

112.89
114.4-114.5

1993

114.3
176.0-176.9

1991

173.0-173.9
203.00

1991

203.0
203.01

1991

V10.79
203.10

1991

203.1
203.11

1991

V10.79
203.80

1991

203.8
203.81

1991

V10.79
204.00

1991

204.0
204.01

1991

V10.61
204.10

1991

204.1
204.11

1991

V10.61
204.20

1991

204.2
204.21

1991

V10.61
204.80

1991

204.8
204.81

1991

V10.61
204.90

1991

204.9
204.91

1991

V10.61
205.00

1991

205.0
205.01

1991

V10.62
205.10

1991

205.1
205.11

1991

V10.62
205.20

1991

205.2
205.21

1991

V10.62
205.30

1991

205.3
205.31

1991

V10.62
205.80

1991

205.8
205.81

1991

V10.62
205.90

1991

205.9
205.91

1991

V10.62
206.00

1991

206.0
206.01

1991

V10.63
206.10

1991

206.1
206.11

1991

V10.63
206.20

1991

206.2
206.21

1991

V10.63
206.80

1991

206.8
206.81

1991

V10.63
206.90

1991

206.9
206.91

1991

V10.63
207.00

1991

207.0
207.01

1991

V10.69
207.10

1991

207.1
207.11

1991

V10.69
207.20

1991

207.2
207.21

1991

V10.69
207.80

1991

207.8
207.81

1991

V10.69
208.00

1991

208.0
208.01

1991

V10.60
208.10

1991

208.1
208.11

1991

V10.60
208.20

1991

208.2
208.21

1991

V10.60
208.80

1991

208.8
208.81

1991

V10.60
208.90

1991

208.9
208.91

1991

V10.60
237.70-237.72

1990

237.7
250.02

1993

250.90
250.03

1993

250.91
250.12

1993

250.10
250.13

1993

250.11
250.22

1993

250.20
250.23

1993

250.21
250.32

1993

250.30
250.33

1993

250.31
250.42

1993

250.40
250.43

1993

250.41
250.52

1993

250.50
250.53

1993

250.51
250.62

1993

250.60
250.63

1993

250.61
250.72

1993

250.70
250.73

1993

250.71
250.82

1993

250.80
250.83

1993

250.81
250.92

1993

250.90
250.93

1993

250.91
278.00-278.01

1995

278.0
283.10-283.11,283.19

1993

283.1
305.1

1994

305.10,305.11,305.12,
305.13 (delete code)
312.81-312.82,381.89

1994

312.8
320.81-320.89

1992

320.8
333.92-333.93

1994

333.99
337.20-337.22,337.29

1993

337.9
342.00-342.02

1994

342.0
342.10-342.12

1994

342.1
342.80-342.82

1994

342.9
342.90-342.92

1994

342.9
344.00-344.04,344.09

1994

344.0
344.30-344.32

1994

344.3
344.40-344.42

1994

344.4
344.81,344.89

1993

344.8
345.00-345.01

1989

345.0
345.10-345.11

1989

345.1
345.40-345.41

1989

345.4
345.50-345.51

1989

345.5
345.60-345.61

1989

345.6
345.70-345.71

1989

345.7
345.80-345.81

1989

345.8
345.90-345.91

1989

345.9
346.00-346.01

1992

346.0
346.10-346.11

1992

346.1
346.20-346.21

1992

346.2
346.80-346.81

1992

346.8
346.90-346.91

1992

346.9
355.71

1993

354.4
355.79

1993

355.7
371.82

1992

371.89
374.87

1990

374.89
403.00-403.01

1989

403.0
403.10-403.11

1989

403.1
403.90-403.91

1989

403.9
404.00-404.03

1989

404.0
404.10-404.13

1989

404.1
404.90-404.93

1989

404.9
410.00-410.02

1989

410.0
410.10-410.12

1989

410.1
410.20-410.22

1989

410.2
410.30-410.32

1989

410.3
410.40-410.42

1989

410.4
410.50-410.52

1989

410.5
410.60-410.62

1989

410.6
410.70-410.72

1989

410.7
410.80-410.82

1989

410.8
410.90-410.92

1989

410.9
411.81

1989

410.9
411.89

1989

411.8
414.00-414.01

1994

414.0
414.02-414.03

1994

996.03
415.11

1995

997.3 & 415.1
415.19

1995

415.1
429.71

1989

410.0-410.9
429.79

1989

410.0-410.9
433.00-433.01

1993

433.0
433.10-433.11

1993

433.1
433.20-433.21

1993

433.2
433.30-433.31

1993

433.3
433.80-433.81

1993

433.8
433.90-433.91

1993

433.9
434.00-434.01

1993

434.0
434.10-434.11

1993

434.1
434.90-434.91

1993

434.9
435.3

1995

435.0 & 435.1
437.7

1992

780.9
440.20-440.22

1992

440.2
440.23

1993

440.20 & 707.1 or 707.8 or 707.9
440.24

1993

440.20 & 785.4
440.29

1993

440.20
440.30-440.32

1994

996.1
441.00-441.03

1994

441.0
441.6

1993

441.1 & 441.3
441.7

1993

441.2 & 441.4
446.20-446.21,446.29

1990

446.2
451.82-451.84

1993

451.89
458.2

1995

997.9 & 458.9
482.30-482.39

1992

482.3
482.81-482.89

1992

482.8
483.0

1992

483
483.8

1992

483
491.20-491.21

1991

491.2
493.20

1989

493.90
493.21

1989

493.91
512.1

1994

997.3
518.81

1987

799.1
518.82-518.89

1987

518.8
524.00-524.09

1992

524.0
524.10-524.19

1992

524.1
524.60-524.69

1991

524.6
524.70-524.79

1992

524.8
530.10-530.11, 530.19

1993

530.1
530.81

1993

530.1
530.82-530.84, 530.89

1993

530.8
535.00-535.01

1991

535.0
535.10-535.11

1991

535.1
535.20-535.21

1991

535.2
535.30-535.31

1991

535.3
535.40-535.41

1991

535.4
535.50-535.51

1991

535.5
535.60-535.61

1991

535.6
536.3

1994

536.8
537.82

1990

537.89
537.83

1991

537.82
556.0-556.6

1994

556
556.8-556.9

1994

556
562.02

1991

562.00
562.03

1991

562.01
562.12

1991

562.10
562.13

1991

562.11
569.60-569.61

1995

569.6
569.69

1995

569.6
569.84

1990

557.1
569.85

1991

569.84
593.70-593.73

1994

593.7
596.51-596.53

1992

596.5
596.54

1992

344.61
596.55-596.59

1992

596.5
599.81-599.89

1992

599.8
645.0

1991

645
651.30-651.31,651.33

1989

651.00-651.01,651.03
651.40-651.41,651.43

1989

651.10-651.11,651.13
651.50-651.51,651.53

1989

651.20-651.21,651.23
651.60-651.61,651.63

1989

651.80-651.81,651.83
654.20-654.21,654.23

1990

654.2,654.9
654.90-651.94

1990

654.2,654.9
657.0

1991

657
659.60,659.61,659.63

1992

659.80,659.81,659.83
665.10,665.11

1992

665.10,665.11,665.12,665.14
Note: The title for the subcategory, 665.1 has been changed,
making the fifth-digit subclassification, 665.12 and 665.14
invalid.
670.0

1991

670
672.0

1991

672
677

1994

* No previous code assignments.
690.10

1995

690
690.11

1995

691.8 & 704.8
690.12

1995

691.8
690.18

1995

690
690.8

1995

690
692.72-692.74

1992

692.79
692.82-692.83

1992

692.89
702.0-702.8

1991

702
702.11,702.19

1994

702.1
704.02

1993

704.09
709.00-709.01,709.09

1994

709.0
710.5

1992

288.3,729.1
728.86

1995

729.4
733.10-733.16, 733.19

1993

733.1
738.10-738.19

1992

738.1
747.60-747.64, 747.69

1993

747.6
747.82

1993

747.89
753.10-753.17,753.19

1990

753.1
759.81-759.89

1989

759.8
759.83

1994

759.89
760.75

1991

760.79
760.76

1994

760.79
764.00-764.09

1988

764.0
764.10-764.19

1988

764.1
764.20-764.29

1988

764.2
764.90-764.99

1988

764.9
765.00-765.09

1988

765.0
765.10-765.19

1988

765.1
780.01-780.09

1992

780.0
780.03

1993

780.01
780.57

1992

780.51,780.53
781.8

1994

781.9
787.01-787.03

1994

787.0
787.91

1995

558.9
787.99

1995

787.9
788.20-788.21, 788.29

1993

788.2
788.30-788.39

1992

788.3
788.41-788.43

1993

788.4
788.61-788.62, 788.69

1993

788.6
789.00-789.07, 789.09

1994

789.0
789.30-789.37, 789.39

1994

789.3
789.40-789.47, 789.49

1994

789.4
789.60-789.67, 789.69

1994

789.6
790.91

1993

790.9
790.92

1993

286.9
790.93, 790.99

1993

790.9
795.71

1994

795.8 (delete code)
795.79

1994

795.7
795.8

1986

795.7
864.05

1992

864.09
864.15

1992

864.19
909.5

1994

909.9
925.1-925.2

1993

925
989.81-989.84

1995

989.8
989.89

1995

989.8
995.60-995.69

1993

995.0
996.04

1994

996.09
996.51-996.59

1987

996.5
996.60-996.69

1989

996.6
996.70-996.79

1989

996.7
996.80-996.89

1987

996.8
996.85

1990

999.8
997.00-997.01

1995

997.0
997.02

1995

997.9 & 430-434, 436
997.09

1995

997.0
997.91

1995

997.9
997.99

1995

997.9
998.81-998.82, 998.89

1994

998.8
V03.81-V03.82, V03.89

1994

V03.8
V05.3-V05.4

1993

V05.8
V06.5-V06.6

1994

V06.8
V07.31,V07.39

1994

V07.3
V07.4

1992

V07.8
V08

1994

044.9, 795.8 (delete code)
V09.0-V09.91

1993

* No previous code assignments
V12.00-V12.03, V12.09

1994

V12.0
V12.50-V12.52

1995

V12.5
V12.59

1995

V12.5
V12.70-V12.72, V12.79

1994

V12.7
V13.00-V13.01, V13.09

1994

V13.0
V15.82

1994

305.13 (delete code)
V15.84-V15.86

1995

V15.89
V25.43

1992

V25.49
V25.5

1992

V25.8
V29.0-V29.8

1992

V71.8
V29.9

1992

V71.9
V30.00-V30.01

1989

V30.0
V31.00-V31.01

1989

V31.0
V32.00-V32.01

1989

V32.0
V33.00-V33.01

1989

V33.0
V34.00-V34.01

1989

V34.0
V35.00-V35.01

1989

V35.0
V36.00-V36.01

1989

V36.0
V37.00-V37.01

1989

V37.0
V39.00-V39.0l

1989

V39.0
V43.60-V43.66, V43.69

1994

V43.6
V43.81-V43.82

1995

V43.8
V43.89

1995

V43.8
V45.00

1994

V45.89
V45.01

1994

V45.0
V45.02, V45.09

1994

V45.89
V45.51

1994

V45.5
V45.52, V45.59

1994

V45.89
V45.82

1994

V45.89
V45.83

1995

V45.89
V49.60-V49.67

1994

V49.5
V49.70-V49.77

1994

V49.5
V50.41-V50.42, V50.49

1994

V50.8
V53.31

1994

V53.3
V53.32, V53.39

1994

V53.9
V56.1

1995

V58.89
V57.21-V57.22

1994

V57.2
V58.41, V58.49

1994

V58.4
V58.61

1995

V67.51
V58.69

1995

V67.51
V58.81, V58.89

1994

V58.8
V58.82

1995

V58.89
V59.01-V59.02

1995

V59.0
V59.09

1995

V59.0
V59.6

1995

V59.8
V65.40-V65.45, V65.49

1994

V65.4
V69.0-V69.3

1994

* No previous code assignments.
V69.8-V69.9

1994

* No previous code assignments.
V72.81-V72.85

1993

V72.8
V73.88-V73.89

1993

V73.8
V73.98-V73.99

1993

V73.9
E854.8

1995

E858.8
E869.4

1994

E869.8
E880.1

1995

E884.9
E884.3-E884.4

1995

E884.2
E884.5-E884.6

1995

E884.9
E906.5

1995

E906.3
E908.0-E908.4

1995

E908
E908.8-E908.9

1995

E908
E909.0-E909.4

1995

E909
E909.8-E909.9

1995

E909
E920.5

1995

E920.4
E924.2

1995

E924.0
E968.5

1995

E968.8
  
PROCEDURE CODES
PROCEDURE CODES

Effective

Current code(s) assignment

October 1

Previous code(s) assignment
2.96

1992

89.19
3.9

1987

03.99 (Insertion of Catheter)
5.25

1995

39.7 (delete)
11.75

1989

11.79
11.76

1989

11.62
20.96-20.98

1986

20.95
22.12

1988

22.11
26.12

1988

26.11
29.31

1991

83.02
29.32

1991

29.3
29.33

1991

29.3
29.39

1991

29.3
31.45

1988

31.43-31.44
31.95

1989

31.75
32.01

1989

32
32.09

1989

32
32.22

1995

32.29, 32.9
32.28

1989

32.29
33.27

1987

33.22 + 33.27
33.28

1987

33.27
33.29

1987

33.28-33.29
33.5

1995

33.5
33.51

1995

33.5
33.52

1995

33.5
33.6

1990

33.5 + 37.5
34.05

1994

34.99
35.84

1988

35.82
35.96

1986

35.03
36.00-36.03

1986

36
36.04

1986

39.97
36.05

1987

36.01
36.05

1986

36.01 (Before October 1986 contents of current code 36.05 would have been assigned to 36.0), 36.02
36.06

1995

36.01, 36.02, 36.03, 36.05
36.09

1986

36
36.09

1991

36.00 (Code Deleted)
37.26-37.27

1988

37.29
37.34

1988

37.33
37.65

1995

37.62
37.66

1995

37.62
37.70 (Leads only)

1987

37.70 (Leads/Device)
37.71-37.72 (Leads only)

1987

37.74 (Leads/Device)
37.73 (Leads only)

1987

37.73 (Leads/Device)
37.74 (Leads only)

1987

37.76 (Leads/Device)
37.75 (Leads only)

1987

37.89 (Leads/Device)
37.76 (Leads only)

1987

37.81 (Leads/Device)
37.77 (Leads only)

1987

37.83-37.84 (Leads/Device)
37.78

1987

37.71-37.72
37.79

1987

86.09
37.80-37.87

1992

89.49 (Code deleted, this procedure is included in the code for pacemaker insertion/replacement)
37.80 (Device only)

1987

37.73-37.77 (Leads/Device)
37.81 (Device only)

1987

37.73-37.77 (Leads/Device)
37.82 (Device only)

1987

37.73-37.77 (Leads/Device)
37.83 (Device only)

1987

37.73-37.77 (Leads/Device)
37.85-37.87

1987

37.85
37.89

1987

37.86 + 37.89
37.94-37.98

1986

37.99
38.22

1986

38.29
38.44 (Abdominal Aorta Only)

1986

38.44 (Entire Aorta)
38.45 (Thoracic Aorta Added)

1986

38.44-38.45
38.95

1989

38.93
39.28

1991

39.29
39.5

1995

39.59
39.65

1988

39.61
39.66

1990

39.65
41.00-41.03

1988

41
41.04

1994

99.79
42.25

1988

42.24
42.33

1989

42.32, 42.39
42.33

1990

42.91
43.11

1989

43.1
43.19

1989

43.1, 43.2
43.41

1989

43.41,43.49
44.21

1986

44.2
44.22

1986

44.99
44.29

1986

44.2
44.43

1989

43.49,45.32
44.44

1989

38.86
44.49

1989

43
44.93-44.94

1986

44.99
45.16

1988

45.14 (45.15 before 1987)
45.3

1989

45.31,45.32
45.42

1988

45.41
45.43

1989

45.49
45.75 (Hartmann Resection Added)

1988

48.66 (Code Deleted)
45.95

1987

45.93
46.13

1992

46.12 (Code Deleted)
46.32

1989

46.39
46.85

1989

46.99
48.36

1995

45.42
49.31

1989

49.3
49.39

1989

49.3
51.1

1989

51.97
51.11

1989

51.11,51.97
51.14

1989

51.12
51.15

1989

51.97
51.22

1991

51.21 (Code Deleted),51.22
51.23

1991

51.22
51.64

1989

51.69
51.84-51.88

1989

51.97
51.97

1986

52.91,51.99, or 51.82
51.98

1986

51.99
52.13

1989

51.97,52.91
52.14

1989

52.11
52.21

1989

52.2
52.22

1989

52.2
52.93

1989

52.93 + 52.91
52.94

1989

52.09
52.97

1989

52.91
52.98

1989

52.91
52.99

1989

52.93,52.94,52.99
54.24

1987

54.23
54.25

1993

54.98
55.03-55.04

1986

55.02
56.33-56.34

1987

56.33
56.35

1987

45.12
57.17-57.18

1989

57.21
57.22

1989

57.22,57.82
58.31

1990

58.3
58.39

1990

58.3
58.93

1986

57.99
59.72

1995

59.79
59.96

1986

59.95
60.21

1995

60.2
60.29

1995

60.2
60.95

1991

60.99
64.97

1986

64.95
66.01

1992

66
66.02

1992

66.73
68.15

1987

68.14
68.16

1987

68.13
68.9

1992

68.4
74.3

1992

69.11 (Code Deleted)
77.56

1989

77.89,78.49,81.18
77.57

1989

77.89,80.48,81.18,83.85
77.58

1989

77.59,81.18
78.1

1991

78.4
78.11

1991

78.41
78.12

1991

78.42
78.13

1991

78.43
78.14

1991

78.44
78.15

1991

78.45
78.16

1991

78.46
78.17

1991

78.47
78.18

1991

78.48
78.19

1991

78.49
78.2

1991

78.10,78.20,78.30
78.21

1991

78.11,78.31
78.22

1991

78.12,78.22,78.32
78.23

1991

78.13,78.23,78.33
78.24

1991

78.14,78.34
78.25

1991

78.15,78.25,78.35
78.27

1991

78.17,78.27,78.37
78.28

1991

78.18,78.38
78.29

1991

78.11,78.16,78.19,78.29,78.39
78.39

1991

78.31
78.90 (1)

1987

78.4
78.91 (1)

1987

78.41
78.92 (1)

1987

78.42
78.93 (1)

1987

78.43
78.94 (1)

1987

78.44
78.95 (1)

1987

78.45
78.96 (1)

1987

78.46
78.97 (1)

1987

78.47
78.98 (1)

1987

78.48
78.99 (1)

1987

78.49
80.50-80.59

1986

80.5
81.03

1989

81.02
81.04-81.05

1989

81.03,81.04,81.05
81.06-81.07

1989

81.06,81.07
81.08

1989

81.06,81.07,81.08
81.09

1989

81.08
81.4

1989

81.69
81.51

1989

81.51,81.59
81.52

1989

81.61,81.62,81.63,81.64
81.53

1989

81.51,81.59,81.61,81.62,
81.63,81.64
81.54-81.55

1989

81.41
81.56

1989

81.48
81.57

1989

81.31,81.39
81.59

1989

81.39
81.72

1989

81.79
81.73-81.74

1989

81.86
81.75

1989

81.87
81.79

1989

81.79,81.87
81.8

1989

81.81
81.97

1992

81.59
85.95

1987

85.99
85.96

1987

85.99
86.06

1987

86.09
86.07

1990

86.09
86.27

1986

86.22-86.23
86.28

1988

86.22
86.93

1987

86.89
88.9

1986

88.39
88.91

1986

89.15
88.92

1986

89.39
88.93

1986

89.15
88.94

1986

89.39
88.95

1986

89.29
88.97

1989

88.99
88.98

1989

88.9
88.99

1986

89.39
89.1

1989

89.15
89.17-89.18

1988

89.15
89.19

1989

89.15
89.5

1991

89.54
92.3

1995

01.59, 04.07, 07.63, 07.68
93.9

1988

93.92
94.61-94.69

1989

94.25
96.6

1986

96.35
96.7

1991

93.92 (Code Deleted)
96.71

1991

93.92 (Code Deleted)
96.72

1991

93.92 (Code Deleted)
97.05

1989

51.97
98.51-98.52

1989

59.96 (Code Deleted)
98.59

1989

59.96 (Code Deleted)
99

1995

99.02
99.15

1986

99.29
99.28

1994

99.25
99.71-99.79 (2)

1988

99.07
99.85

1987

93.35
99.86

1987

93.39
99.88

1988

99.83
(1) Codes 78.90-78.99 were retitled as "Insertion of bone growth
stimulator" in October 1987; the previous contents of codes
78.90-78.99 were reassigned to codes 78.40-78.49.
(2) Codes 99.71-99.79 were deleted in October 1987; their contents
were not transferred elsewhere. In the October 1988 revision,
codes 99.71-99.79 were reclassified as "Therapeutic apheresis."
  
  
APPENDIX C  
  Historically, operative and surgical procedures were categorized into four classes,
  according to UHDDS guidelines.  Classes 1-3 consisted of significant procedures, i.e.
  those that carried an operative or anesthetic risk or required highly trained personnel,
  special facilities, or special equipment.  Class 4 procedures were not considered
  significant; therefore, reporting was optional.  From 1979 through the middle of 1983,
  only three Class 4 procedures were coded for the NHDS: circumcision, episiotomy, and
  removal of intrauterine contraceptive device.  Since the last half of 1983, additional codes
  were added, until 1991, when all procedures were coded.    
  It is important to remember that, because many procedure codes were not utilized
  between 1979 and 1990, it is not possible to produce estimates for those codes.  The table
  contained in this appendix lists the procedures not coded and the year the code was first
  used.   Caution should be exercised when producing estimates for these codes.
CLASS 4 PROCEDURES AND YEAR CODE FIRST USED IN NHDS
ICD-9-CM

First

ICD-9-CM

First

ICD-9-CM

First

ICD-9-CM

First

Procedure Code

used

Procedure Code

used

Procedure Code

used

Procedure Code

used

01.18-01.19

1983

38.29

1983

71.19

1983

89.66

1989

03.39

1983

40.19

1983

73.6-

1979

89.7-

1991

04.19

1983

41.38-41.39

1989

73.91-73.92

1989

90.01-91.99

1991

05.19

1983

42.29

1989

75.35

1989

93.01-93.25

1991

06.19

1983

44.91

1989

76.19

1983

93.27-93.28

1991

07.19

1983

45.19

1989

78.80-78.89

1983

93.31-93.39

1991

08.19

1989

45.28-45.29

1989

81.98

1983

93.42-93.44

1989

08.91-08.93

1983

48.23

1989

83.29

1983

93.61-93.89

1991

09.19

1983

48.29

1989

85.19

1989

93.91

1991

09.41-09.49

1983

49.21

1989

86.19

1989

93.94

1989

10.29

1983

49.29

1989

86.92

1989

93.96

1989

11.29

1983

49.41

1989

87.09-87.12

1991

93.99

1989

12.29

1983

50.19

1983

87.16-87.17

1991

94.01-94.23

1991

14.19

1983

51.19

1983

87.22-87.29

1991

94.25

1991

15.09

1983

52.19

1983

87.36-87.37

1989

94.29-94.59

1991

16.21

1989

54.29

1983

87.39

1991

95.01-95.03

1991

16.29

1983

55.29

1983

87.43-87.49

1991

95.05-95.11

1991

18.01

1989

56.39

1983

87.69

1989

95.14-95.15

1991

18.11

1989

57.39

1983

87.79

1989

95.31-95.48

1991

18.19

1989

58.29

1989

87.85-87.89

1991

95.49

1989

20.39

1983

59.29

1983

87.92

1991

96.09

1989

21.21

1989

60.18

1983

87.95-87.99

1991

96.11-96.19

1991

21.29

1989

61.19

1989

88.09

1991

96.26-96.28

1991

22.19

1989

62.19

1983

88.16-88.31

1991

96.34-96.59

1991

24.19

1989

63.09

1983

88.33

1991

97.01-97.04

1991

25.09

1989

64.0-

1979

88.35

1991

97.14-97.69

1991

25.91

1989

64.19

1989

88.37

1991

97.71

1979

26.19

1989

64.91

1989

88.39

1991

97.72-97.89

1991

27.29

1989

64.94

1989

89.01-89.09

1991

99.02-99.14

1991

27.91

1989

65.19

1983

89.11-89.13

1991

99.16-99.24

1991

28.19

1983

66.19

1983

89.15-89.16

1991

99.26-99.59

1991

29.19

1989

67.19

1983

89.26-89.31

1991

99.71-99.79

1989

31.48-31.49

1989

68.19

1983

89.33-89.39

1991

99.82-99.84

1990

33.28-33.29

1983

69.92

1989

89.45-89.49

1989

99.91-99.99

1990

34.28-34.29

1983

70.21

1989

89.51-89.53

1989

37.29

1989

70.29

1983

89.55-89.59

1989

 

APPENDIX D                              
  The standard error is primarily a measure of sampling variability that occurs by chance
  because only a sample rather than the entire universe is surveyed.  The relative standard
  error of an estimate is obtained by dividing the standard error by the estimate itself. 
  When the resulting value is multiplied by 100, the relative standard error is expressed as a
  percent of the estimate.    
  Before 1988, standard error estimates were produced using a computerized routine based
  on a rigorously unbiased algebraic estimator of the variance.  Since 1988, estimates of
  sampling variability have been calculated with SESUDAAN or SUDAAN software,
  which computes standard errors by using a first-order Taylor series approximation of the
  deviation of estimates from their expected values.  A description of the software and the
  approach it uses was published by Shah (see Reference 8).  Neither of these methods is
  available to analysts outside the NCHS/CDC research community.  
  In order to obtain standard errors that would be applicable for a wide variety of statistics
  and that could be prepared at a moderate cost, a method using generalized variance curves
  was developed.  Numerous variances were calculated and a best fit formula was derived
  which was based on an empirically determined relationship between the size of an
  estimate, X, and its relative variance. The relative standard error was then obtained by
  taking the square root of the relative variance. These generalized variance curves
  provided approximations to the relative standard errors that were applicable to estimates
  of discharges, first- or all-listed diagnoses, all-listed procedures, and days of care, either
  aggregated or disaggregated by selected patient or hospital characteristics.    
  This appendix contains information needed to produce generalized errors for NHDS
  statistics.  For the years 1979 through 1987, curves are represented in tables containing
  selected estimates of different sizes and their approximate relative standard errors. For the
  years 1988 through the present, tables containing parameter values for relative standard
  error curves are given.  Instructions on how to use this information follows. The RSE
  tables and curves for each data year are contained in separate files which are available on
  a computer disk provided with this documentation. 
  
  COMPUTATION OF RELATIVE STANDARD ERRORS FOR AGGREGATE
  ESTIMATES, 1979 THROUGH 1987 DATA YEARS  
  For each of the years from 1979 through 1987, there are files containing approximate
  relative standard errors (RSEs) for estimates of various sizes for discharges, first- or
  all-listed diagnoses, all-listed procedures, and days of care.  Because RSEs may differ
  depending on the characteristic which is being estimated, more than one RSE curve is
  usually presented.  Also, since it is not possible to provide exact standard errors for every
  size estimate, it is necessary to use arithmetic interpolation to obtain the RSE for an
  estimate not included in the table.  Linear interpolation is used for simplicity and without
  loss of accuracy, even though the curves are not strictly speaking linear functions.   
  For example, in 1979 the estimated number of appendectomies (ICD-9-CM code 47.0)
  performed on patients 15 years and older discharged from short-stay hospitals was
  232,000.  Referring to the file, RSE79.WK1, there is no curve by age, so the one entitled
  "All Other Variables" is used. Also, the estimate 232,000 is not listed, so in order to
  obtain an approximate RSE, arithmetic interpolation is performed as follows.    
  Step 1.  In the column headed "Size of Estimate", locate the two adjacent values between
  which the estimate of interest is located.  In this example, they would be 100,000 and
  250,000.    
  Step 2.  For these estimates, compute estimated standard errors, using the corresponding
  RSEs from the column headed "All Other Variables".  
  
       SE(100,000) = 9.9% * 100,000 = 9,900 
       SE(250,000) = 8.6% * 250,000 = 21,500  
  
  Step 3.  Calculate the proportional part of the interval between 100,000 and 250,000
  which falls between 100,000 and 232,000.          
  
       P = (232,000 - 100,000) / (250,000 - 100,000)  = .88
  
  Step 4.  Calculate the estimated standard error of 232,000 by subtracting the proportional
  part of the interval between the two standard errors from the standard error of 100,000.      
       SE(232,000) = SE(100,000) - P * (SE(100,000) - SE(250,000))
       SE(232,000) = 9,900 - .88 * (9,900 - 21,500) = 20,108
  
  The relative standard error can be obtained by dividing the standard error by the estimate:  
  
       RSE(232,000) =  20,108 / 232,000 = .087
  
  When multiplied by 100, the RSE is expressed as a percent of the estimate (i.e. 8.7%).  
  The standard error can be employed to generate confidence intervals for statistical testing. 
  In this example, the two-tailed, 95% confidence interval for the estimate of
  appendectomies for inpatients aged 15 and older in 1979 is:
  
       LOWER LIMIT:    232,000 - 1.96 * 20,108 = 192,588
       UPPER LIMIT:    232,000 + 1.96 * 20,108 = 271,412
  
  COMPUTATION OF RELATIVE STANDARD ERRORS FOR PERCENTS, 1979
  THROUGH 1987 DATA YEARS
  
  The relative standard error of a percent in which both the numerator (X) and denominator
  (Y) are from NHDS is estimated by:
  
       RSE(X/Y) = SQRT {[SE(X)^2 / X^2] - [SE(Y)^2 / Y^2]}
  
  To verbally clarify this formula, the RSE(X/Y) is obtained by taking the square root of
  the difference between two quantities.  The first of the two quantities is obtained by
  dividing the squared standard error of X by X-squared; the second of the two quantities is
  obtained by dividing the squared standard error of Y by Y-squared.  When RSE(X/Y) is
  multiplied by 100, then RSE(X/Y) is expressed as a percent of the estimate.
    
  For example, the estimated 232,000 appendectomies performed on patients aged 15 years
  and older represent 74.6% of the estimated 311,000 appendectomies in 1979.  To
  compute the relative standard error of this percent, the standard errors of both the
  numerator and the denominator are needed.  The standard error of the numerator is given
  above.  The standard error of the denominator can be calculated using the procedure
  described in the preceding section and is found to be 25,770.  Using these figures in the
  formula gives:
  
       RSE(.746) = SQRT [(20,108^2 / 232,000^2) - (25,770^2 / 311,000^2)]  = .025
  
  Expressed as a percent, RSE(.746) = 2.5%. 
  
  The standard error of the percent can be obtained by multiplying the percent by its RSE:    
  
       SE(.746) =  RSE(.746) * .746 = .025 * .746 = .019
  
  The standard error can be employed to generate confidence intervals around the estimate,
  as shown above.
  
  COMPUTATION OF RELATIVE STANDARD ERRORS FOR AGGREGATE
  ESTIMATES,  1988 THROUGH 1996 DATA YEARS
  
  The relative standard error of an estimate, RSE(X), may be calculated from the formula:
  
       RSE(X) = SQRT( a + b/X) 
  
  with a and b provided in the accompanying files.  When multiplied by 100, RSE(X) is
  expressed as a percent of X.  
  
  For example, in 1992 the estimated number of discharges from short-stay hospitals for
  females with a first-listed diagnosis of atherosclerotic heart disease (ICD-9-CM code
  414.0) was 130,000. Using the file, RSE92.WK1, in Appendix D for estimates by sex, the
  value of a is .00089 and the value for b is 404.530.  Thus,
  
       RSE(130,000) = SQRT [.00089 + (404.530 / 130,000)]  = .0633
  
  Expressed as a percent, RSE(130,000) = 6.33%. 
  
  The standard error of the estimate is obtained by multiplying the relative standard error by
  the estimate itself:
  
       SE(130,000) =  130,000 * .0633  =  8,229
  
  The standard error can be employed to generate confidence intervals for statistical testing. 
  In this example, the two-tailed, 95% confidence interval for the estimate of female
  inpatients with a first-listed diagnosis of atherosclerotic heart disease in 1992 is:
  
       LOWER LIMIT:   130,000 - 1.96 * 8,229 = 113,871
       UPPER LIMIT:     130,000 + 1.96 * 8,229 = 146,129
  
  COMPUTATION OF RELATIVE STANDARD ERRORS FOR ESTIMATES OF
  PERCENTS, 1988 THROUGH 1996
  
  Approximate relative standard errors for estimates of percents may be calculated from the
  tables in Appendix D also.  The relative standard error for a percent, 100 * p (0<p<1),
  may be calculated using the formula:
  
       RSE(p) = SQRT [b * (1 - p)/(p * X)]
  
  where 100 * p is the percent of interest, X is the base of the percent, and b is the
  parameter b in the formula for approximating the RSE(X).  Values for b are given in the
  accompanying files.
  
  For example, in 1992 the estimated number of discharges from short-stay hospitals which
  were female was 18,545,000.  This is 59.9 percent of the estimated 30,951,000 discharges
  for that year.  Using the file, RSE92.WK1, in Appendix D for estimates by sex, the value
  of b is 404.530.  Thus, 
  
       RSE(.599) = SQRT [404.530 * (1 - .599) / (.599 * 30,951,000)]  = 0.00296
  
  The relative standard error for the estimate of interest is 0.00296.  Expressed as a percent,
  RSE(.599) = .296%.  From this the standard error is obtained by multiplying the relative
  standard error by the estimate:          
  
       SE(.599) = .599 * 0.00296 = 0.00177.
  
  The standard error can be employed to generate confidence intervals for statistical testing,
  as shown above. 
  
  COMPUTATION OF  RELATIVE STANDARD ERRORS OF RATES IN WHICH THE
  DENOMINATOR HAS NO SAMPLING ERROR
  
  It is generally assumed that population estimates which are obtained from the Bureau of
  the Census for certain overall totals, such as the U.S. population and subgroups
  disaggregated by age, sex, race, and region, are not subject to sampling error or that the
  error may be small enough to be considered negligible.  The relative standard error of
  rates formed with these populations as the denominator is the relative standard error of
  the numerator.  Thus, to obtain the standard error of the rate, simply multiply the rate
  itself by the RSE of the numerator.  
  
  COMPUTATION OF RELATIVE STANDARD ERRORS FOR MULTIPLE YEAR
  ESTIMATES, 1979 THROUGH 1996
  
  This section presents procedures which may be used to approximate sampling errors of
  estimates based on multiple years of data collected under either or both of the 1965 and
  1988 NHDS sample designs.  These procedures are not considered final.  However, they
  will permit approximating variances for multi-year estimates until research into
  potentially improved methods can be completed for estimates based on the 1988 sample
  design.  It is believed the approximations are conservative and, hence, should not indicate
  significance when the contrary is actually true.
  
  VARIANCE OF ESTIMATED TOTALS FOR MULTIPLE YEARS
  
  For discussion purposes, let X' equal the multi-year aggregate estimate for the
  characteristic of interest.  That is,
  
       X' = sum of annual aggregate estimates for any characteristic of interest 
               for any number of years (say, Y years)
  
  If the annual estimates are all from years between 1965 and 1987, then 
  
       X'65 = sum of annual aggregate estimates for any characteristic of interest
            for any number of years between 1965 and 1987
  
  If the annual estimates are all from years between 1988 and the present, then
  
       X'88 = sum of annual aggregate estimates for any characteristic of interest
            for any number of years between 1988 and 1996
  
  If the annual estimates are from years in both the 1965 and 1988 samples, then
  
       X' = X'65 + X'88
  
  The procedure for approximating the variance of X'  differs depending on the set Y of
  years in the database for X'.  
  
  SITUATION A.  
  When the data base includes only years from the period 1965-1987, the following formula
  is used:
  
       VAR(X'65) = (X'65)^2 * [RSE(X'65|Y years)]^2                                        (1)
  
  where 
  
       RSE(X'65|Y years) = [SQRT (R|Y years)] * max [RSE (X'65|1 year)]        (2)
  
  and
       max [RSE (X'65|1 year)] = maximum relative standard error over Y years
                                 calculated as though X'65 were based only on data
                                 from the single year, y.
  
  (Instructions for determining the RSE for a single year estimate are given above.)
  
  The value R in (2) above is calculated as follows.  
  (Attachment D1 in this Appendix presents a derivation of the R factor).
  
       R|Y years = (alpha * average-n) + 500                                                      (3)
                    alpha * (average-n + 500)
  
       where 
            alpha = the number of years from the 1965-1987 period which are
                 included in the data base for X'65
  
            average-n = the average number of sampled discharges per hospital 
                        per year in the data base for X'65 (Attachment D1 explains
                        the calculation of average-n).
  
  For example, assume an estimated 10,000 discharges during the data years 1986-1987
  were to patients receiving surgery "S" during their stays.  Here, 
  
       X'65 = 10,000 discharges, Y = {1986, 1987}, and alpha = 2.
  
       RSE (X'65|1 year, 1986) = .102   (From published RSE curves)
  
       RSE (X'65|1 year, 1987) = .105   (From published RSE curves)
  
  Hence, max [RSE (X'65|1 year)] = max [.102, .105] = .105
  
  Using data from Attachment D2 in this Appendix, the average number of discharges per
  respondent hospital per year is calculated as:
  
       average-n = 193,000 + 181,000    = 457.2
                   ___________________
                          418 + 400
  
   The use of alpha and the above in equation (3) gives:
  
       R|Y years = (alpha * average-n) + 500 = 2 (457.2) + 500 = 1,414.4 = .739
                    ____________________________________________________
                    alpha * (average-n + 500)    2 (457.2 + 500)    1,914.4 
  
  Substituting in equation (2),
  
       RSE(X'65|2 years) = [SQRT (.739)] * .105 = .09
  
  And, by equation (1), the variance of the multi-year aggregate X'65 is
  
       Var(X'65|years 1986 & 1987) = {[(10,000)^2] * [(.09)^2]} = 810,000.        
  
  SITUATION B.  
  When the data base includes only years from the period 1988 through the present, then
  equation (1) above is used, but the calculation of the single year RSE is different.  The
  following formula is used to the calculate the RSE of any single year estimate from 1988
  through 1996.
  
       RSE(X'88 |1 year) = SQRT (a + b/X)                                                          (4)
  
  The parameters a and b are given in the files accompanying this document.
  (This approximation for the variance of X'88 ignores any reductions in the variance which
  may result from relationships between the first, second, and third stage components in the
  variance when estimates are based on the 1988 NHDS sample design.  That relationship
  and the magnitude of its effects on the variances is unknown at this writing.) 
  
  For example, assume an estimated 10,000 discharges during the data years 1988-1989
  were to patients receiving surgery "S" during their stays.  Here, 
  
       X'88 = 10,000 discharges,  Y = {1988, 1989}, and alpha = 2.
  
  Using equation (4) above, the following is obtained:
                                                                                                                                            
  Year    a            b            RSE(10,000)                                                                
  ______________________________________________________________________________
  1988  .001591421    403.123981    0.2047   (based on 1988 Data Tape Documentation)
  1989  .0029026252   478.865192    0.2254   (based on 1989 Data Tape Documentation)
  
  Hence, 
  
       max [RSE (X'88|1 year)] = max [.2047, .2254] = .2254    
  
  And, by equation (1), the variance of the multi-year aggregate X'88 is
  
       Var(X'88|years 1988 & 1989) = [(10,000)^2] * [(0.2254)^2] = 5,080,516                
    
  
  SITUATION C.  
  When the data base Y includes years from both the 1965-1987 and the 1988-1996
  periods, the estimate X' and the data base set of years Y may be written as:
  
       X' = X'65 + X'88  and
  
       Y = Y65 + Y88         
  
  where the X' and Y denote, respectively, the multi-year estimate and the set of years when
  data collection is restricted to either the '65 sample design or the '88 sample design. 
  
  Then, because the two samples were selected independently of each other, the variance
  becomes 
  
       Var(X') = Var(X'65) + Var (X'88) ,                                                             (5)
  
  Use the procedures given above to approximate Var(X'65) and Var (X'88).
  
  For example, assume an estimated 10,000 discharges had surgery "S" during the data
  years 1986-1987 and another 10,000 discharges had surgery "S" during the data years
  1988-1989.
   
  Here, 
  
       X' = X'65 + X'88 = 10,000 + 10,000 = 20,000 discharges
  
       Y = Y65 + Y88 = {1986, 1987} + {1988, 1989} and
  
       alpha  = 4.
  
  From the examples in situations A and B,  
  
       VAR(10,000|years 1986 and 1987) = 810,000 
       VAR(10,000|years 1988 and 1989) = 5,080,516
  
  Hence, by equation (5), the variance for the multi-year aggregate X' is:
  
       VAR(20,000|years 1986-1989) = 810,000 + 5,080,516 = 5,890,516
  
  VARIANCES OF ESTIMATED AVERAGE ANNUAL TOTALS 
  
  The variance for an average annual total is derived by first approximating the variance for
  X', according to the instructions for the multi-year aggregate estimate.  Then, let  
  
       X' / alpha = the average annual aggregate for the characteristic of interest 
                   for alpha years of data
  
  where
  
       X' =  the multi-year aggregate estimate for the characteristic of interest
  and
       alpha = the total number of years included in the data base for X' 
                   (that is, the number of years in the set of Y years).
  
  Then, the variance for the estimated average annual aggregate is:
  
       VAR (X' / alpha) = VAR(X') / (alpha)^2                                                (6)
  
  SITUATION A.  
  For the average annual aggregate per year, when the data years are all between 1965 and
  1987, using the example cited above,
  
       X'65 / 2 = 10,000 / 2 = 5,000.
  
  Substituting in equation (6) gives the variance of  X'65 / 2:
  
       VAR(X'65 / 2 | years 1986, 1987) = VAR (X'65) / 2^2   
                                  = 810,000 / 2^2 
                                  = 202,500
  
  SITUATION B.  
  For the average annual aggregate per year, when the data years are all between 1988 and
  1996, using the example cited above,
  
        X'88 / 2 = 10,000 / 2 = 5,000
  
  Substituting in equation (6) gives the variance of  X'88 / 2:
  
       VAR(X'88 / 2 | years 1988, 1989) = VAR (X'88) / 2^2  
                                  = 5,080,516 / 2^2 
                                  = 1,270,129
                                
  SITUATION C.  
  For the average annual aggregate per year, when the data years included are from both the
  1965 design and the 1988 redesign, using the example cited above,
  
       X' / 4 = 20,000/4 = 5,000
  
  Substituting in equation (6) gives the variance of  X' / 4:
  
       VAR(X' / 4 | years 1986, 1987, 1988, 1989)  = VAR (X') / 4^2 
                                     =  5,890,516 / 4^2 
                                     =  368,157 
  
  
  
    ATTACHMENT D1.  Factor R for Approximating Rel-variances for  Multi-year
  Estimates from the 1965 NHDS Sample Design.
  
  Here, it is assumed the multi-aggregate estimate X' is based on data collected in the
  NHDS during two or more of the years 1965-1987.  Then the rel-variance of X'65 may be
  approximated by 
  
       RSE^2(X'65|Y years) = R * max [RSE^2(X'65|1 year)]
  
  where
  
       X'65 = the multi-year aggregate estimate of interest.
  
       Y = the set of years in the data base for X'65.
  
       RSE^2(X'65) = the rel-variance of X'65.
  
  For simplicity, assume that the number of sampled hospitals and sampled discharge
  abstracts in the NHDS remain constant over the data years that serve as the reference
  period for the estimate X'65.  Also assume that the total number of abstracts submitted to
  NHDS each of those years is constant.  Let: 
  
       m = the number of hospitals participating in the NHDS  
       n = the number of sample abstracts in the NHDS each year  
       B = the between hospital rel-variance for the population of  discharges    
       W = the within hospital rel-variance for the population of  discharges  
       alpha  = the number of years in the data base Y
  
  A streamlined approximation to the rel-variance of  X'65 based on a single year of data is
  then
  
       RSE^2(X'65|1 year)   = (B^2 / m) + (W^2 / n) = B^2 {(1 / m) + [(W / B) / n]}
  
  During the original work on the NHDS design, values of the ratio W/B were determined
  and found to lie in the range of 300 - 700 with some concentration near 500 (NCHS
  Report Series 2, Number 39).  Hence, for the general statistic, the effect of using alpha
  years of data can be roughly approximated by setting W/B equal to 500.  Then the
  rel-variance for one year of data is approximately
  
       RSE^2(X'65|1 year) = B^2 [(1 / m) + (500 / n)]
  
  and the rel-variance for estimates based on alpha years of data is approximately
  
       RSE^2(X'65|alpha years) = B^2 [(1 / m) + (500 / (alpha*n))]
  
  The ratio of the two rel-variances can thus be formulated as:
  
       RSE^2(X'65|alpha years)    =   (alpha * (n / m)) + 500   =   R
       ______________________          ______________________
         RSE^2(X'65|1 year)            alpha * ((n / m) + 500)
  
  Because in reality, sample sizes can vary across the Y years, the average number of
  sampled abstracts per hospital per year over the Y years in the data base is used in place
  of n/m in R.   That is, in place of n/m, use average-n which is defined as:
  
       average-n =    the total number of sampled discharges over
                      the years included in the data base (n), 
                      divided by the sum of the  number of
                      respondent hospitals over the same time
                      period (m).   NOTE: the number of sampled
                      discharges per year and the number of
                      respondent hospitals per year appear in
                      Attachment D2.
  
  Hence, 
  
       R = (alpha * average-n) + 500
           _________________________
           (alpha * (average-n + 500)         
  
  
  
ATTACHMENT D2:  Numbers of hospitals participating in NHDS and approximate total
  number of sampled discharge abstracts, by year *

 

DATA YEAR NUMBER OF HOSPITALS APPROXIMATE NUMBER

OF SAMPLED DISCHARGE ABSTRACTS

1965

296

100,000

1966

300

137,000

1967

289

145,000

1968

413

210,000

1969

402

208,000

1970

395

205,000

1971

179

200,000

1972

424

225,000

1973

424

225,000

1974

426

227,000

1975

432

232,000

1976

419

223,000

1977

423

224,000

1978

413

219,000

1979

416

215,000

1980

420

224,000

1981

428

227,000

1982

426

214,000

1983

418

206,000

1984

407

192,000

1985

414

195,000

1986

418

193,000

1987

400

181,000

1988

422

250,000

1989

408

233,000

1990

474

266,000

1991

484

274,000

1992

494

274,000

1993

466

235,000

1994

478

277,000

1995

466

263,000

1996

480

282,000

*  From Series 13 reports on Utilization of Short Stay Hospitals in the U.S.A.  LOTUS tables to accompany Appendix D:
  
  RSE79.WK1  -- Approximate relative standard errors of estimated statistics, 1979
  RSE80.WK1  -- Approximate relative standard errors of estimated statistics, 1980
  RSE81.WK1  -- Approximate relative standard errors of estimated statistics, 1981
  RSE82.WK1  -- Approximate relative standard errors of estimated statistics, 1982
  RSE83.WK1  -- Approximate relative standard errors of estimated statistics, 1983
  RSE84.WK1  -- Approximate relative standard errors of estimated statistics, 1984
  RSE85.WK1  -- Approximate relative standard errors of estimated statistics, 1985
  RSE86.WK1  -- Approximate relative standard errors of estimated statistics, 1986
  RSE87.WK1  -- Approximate relative standard errors of estimated statistics, 1987
  RSE88.WK1  -- Estimated parameters for relative standard errors equations 
                 by selected patient and hospital characteristics, 1988
  RSE89.WK1  -- Estimated parameters for relative standard errors equations 
                 by selected patient and hospital characteristics, 1989
  RSE90.WK1  -- Estimated parameters for relative standard errors equations 
                 by selected patient and hospital characteristics, 1990
  RSE91.WK1  -- Estimated parameters for relative standard errors equations 
                 by selected patient and hospital characteristics, 1991
  RSE92.WK1  -- Estimated parameters for relative standard errors equations 
                 by selected patient and hospital characteristics, 1992
  RSE93.WK4  -- Estimated parameters for relative standard errors equations 
                 by selected patient and hospital characteristics, 1993
  RSE94.WK4  -- Estimated parameters for relative standard errors equations 
                 by selected patient and hospital characteristics, 1994
  RSE95.WK4  -- Estimated parameters for relative standard errors equations 
                 by selected patient and hospital characteristics, 1995
  RSE96.WK4  -- Estimated parameters for relative standard errors equations 
                 by selected patient and hospital characteristics, 1996
APPENDIX E  
  This appendix describes the files included on the diskette accompanying this
  documentation, which contain Census Bureau estimates of the U. S. civilian resident
  population, as of July 1, for the years 1979 through 1996.  There are two types of files,
  named either 1YRxx.WK1 or REGxx.WK1.  To select a given year, the "xx" can be
  replaced by the last two-digits of the year desired between 1979 and 1996 (e.g. 79). 
  These estimates are consistent with the population estimates published in Current
  Population Reports, Series P-25.  For the years 1980 through 1996, there are separate
  tables for estimates disaggregated by sex, race, and single-year age groupings and those
  disaggregated by sex, region, and single-year age groupings.  These population estimates
  have been adjusted based on the 1990 decennial census.    
  There is only one spreadsheet for 1979 because data disaggregated by region are not
  available for this year.  Also the figures in the 1979 spreadsheet have been rounded to the
  nearest thousand, whereas those for all the other years are unrounded.  The 1979 data
  were adjusted based on the 1980 Census.  
  It should be noted that rates calculated with these estimates may differ slightly from those
  in published NCHS reports or those calculated from population estimates disseminated
  with the NHDS annual data tape documentation.  Before 1981, estimates of rates of
  discharges and days of care which appeared in published reports from NCHS were
  calculated using the civilian noninstitutional population.  However, beginning in 1981,
  the civilian resident population estimates were used.  The civilian resident population was
  determined to be more appropriate because persons in institutions, for example nursing
  home patients, are hospitalized when necessary.  A report has been published which
  discusses differences in discharge rates based on the different denominators (see
  Reference 9 in documentation).
  LOTUS tables to accompany Appendix E  
  1YR79.WK1 -- Civilian Population of the United States,
                Estimates by Age, Sex, and Race, July 1, 1979
  1YR80.WK1 -- Civilian Population of the United States,
                Estimates by Age, Sex, and Race, July 1, 1980
  1YR81.WK1 -- Civilian Population of the United States,
                Estimates by Age, Sex, and Race, July 1, 1981
  1YR82.WK1 -- Civilian Population of the United States,
                Estimates by Age, Sex, and Race, July 1, 1982
  1YR83.WK1 -- Civilian Population of the United States,
                Estimates by Age, Sex, and Race, July 1, 1983
  1YR84.WK1 -- Civilian Population of the United States,
                Estimates by Age, Sex, and Race, July 1, 1984
  1YR85.WK1 -- Civilian Population of the United States,
                Estimates by Age, Sex, and Race, July 1, 1985
  1YR86.WK1 -- Civilian Population of the United States,
                Estimates by Age, Sex, and Race, July 1, 1986
  1YR87.WK1 -- Civilian Population of the United States,
                Estimates by Age, Sex, and Race, July 1, 1987
  1YR88.WK1 -- Civilian Population of the United States,
                Estimates by Age, Sex, and Race, July 1, 1988
  1YR89.WK1 -- Civilian Population of the United States,
                Estimates by Age, Sex, and Race, July 1, 1989
  1YR90.WK1 -- Civilian Population of the United States,
                Estimates by Age, Sex, and Race, July 1, 1990
  1YR91.WK1 -- Civilian Population of the United States,
                Estimates by Age, Sex, and Race, July 1, 1991
  1YR92.WK1 -- Civilian Population of the United States,
                Estimates by Age, Sex, and Race, July 1, 1992
  1YR93.WK1 -- Civilian Population of the United States,
                Estimates by Age, Sex, and Race, July 1, 1993
  1YR94.WK1 -- Civilian Population of the United States,
                Estimates by Age, Sex, and Race, July 1, 1994
  1YR95.WK4 -- Civilian Population of the United States,
                Estimates by Age, Sex, and Race, July 1, 1995
  1YR96.WK4 -- Civilian Population of the United States,
                Estimates by Age, Sex, and Race, July 1, 1996 
  REG80.WK1 -- Civilian Population of the United States,
                Estimates by Age, Sex, and Region, July 1, 1980
  REG81.WK1 -- Civilian Population of the United States,
                Estimates by Age, Sex, and Region, July 1, 1981
  REG82.WK1 -- Civilian Population of the United States,
                Estimates by Age, Sex, and Region, July 1, 1982
  REG83.WK1 -- Civilian Population of the United States,
                Estimates by Age, Sex, and Region, July 1, 1983
  REG84.WK1 -- Civilian Population of the United States,
                Estimates by Age, Sex, and Region, July 1, 1984
  REG85.WK1 -- Civilian Population of the United States,
                Estimates by Age, Sex, and Region, July 1, 1985
  REG86.WK1 -- Civilian Population of the United States,
                Estimates by Age, Sex, and Region, July 1, 1986
  REG87.WK1 -- Civilian Population of the United States,
                Estimates by Age, Sex, and Region, July 1, 1987
  REG88.WK1 -- Civilian Population of the United States,
                Estimates by Age, Sex, and Region, July 1, 1988
  REG89.WK1 -- Civilian Population of the United States,
                Estimates by Age, Sex, and Region, July 1, 1989
  REG90.WK1 -- Civilian Population of the United States,
                Estimates by Age, Sex, and Region, July 1, 1990
  REG91.WK1 -- Civilian Population of the United States,
                Estimates by Age, Sex, and Region, July 1, 1991
  REG92.WK1 -- Civilian Population of the United States,
                Estimates by Age, Sex, and Region, July 1, 1992
  REG93.WK1 -- Civilian Population of the United States,
                Estimates by Age, Sex, and Region, July 1, 1993
  REG94.WK1 -- Civilian Population of the United States,
                Estimates by Age, Sex, and Region, July 1, 1994
  REG95.WK4 -- Civilian Population of the United States,
                Estimates by Age, Sex, and Region, July 1, 1995
  REG96.WK4 -- Civilian Population of the United States,
                Estimates by Age, Sex, and Region, July 1, 1996
  
APPENDIX F
  
  The following tabulations are provided for the purpose of verifying that data processing
  of the multi-year file is accurate.  Included are tables of estimated discharges,
  disaggregated by sex, age groups, race, discharge status, and region; estimated days of
  care; estimated numbers of selected first-listed and all-listed diagnoses; estimated
  numbers of selected all-listed procedures; and estimated newborn infant discharges,
  disaggregated by sex, region, and health status.  Note that these are weighted frequencies,
  which were produced by applying the weight variable (columns 21-25) to the analysis.

FREQUENCIES FOR NON-NEWBORNS, NHDS, 1979-1996

DATA

YEAR

TOTAL

DISCHARGES

TOTAL

DAYS OF CARE

MALE

FEMALE

UNDER 15

15-44

45-64

65 & UP

1979

36,746,563

264,173,219

14,704,807

22,041,756

3,641,112

15,487,593

8,532,087

9,085,771

1980

37,831,559

274,508,358

15,145,249

22,686,310

3,672,493

15,635,443

8,659,807

9,863,816

1981

38,543,980

277,229,888

15,379,076

23,164,904

3,733,060

15,725,148

8,677,432

10,408,340

1982

38,593,355

272,626,923

15,469,954

23,123,401

3,654,396

15,553,926

8,688,003

10,697,030

1983

38,782,663

268,337,331

15,573,018

23,209,645

3,653,950

15,268,547

8,558,436

11,301,730

1984

37,162,124

244,651,694

14,899,095

22,263,029

3,208,176

14,532,906

8,194,831

11,226,211

1985

35,056,134

226,217,043

14,160,466

20,895,668

2,971,825

13,966,558

7,609,571

10,508,180

1986

34,255,915

218,496,028

13,949,308

20,306,607

2,782,612

13,457,746

7,299,897

10,715,660

1987

33,386,694

214,942,242

13,568,200

19,818,494

2,687,520

13,141,509

7,099,013

10,458,652

1988

31,146,360

203,677,561

12,641,965

18,504,395

2,610,430

11,933,540

6,456,122

10,146,268

1989

30,946,718

200,826,678

12,583,154

18,363,564

2,597,343

11,848,274

6,271,496

10,229,605

1990

30,787,939

197,421,786

12,279,604

18,508,335

2,411,674

11,798,790

6,244,267

10,333,208

1991

31,098,002

199,098,663

12,478,352

18,619,650

2,498,479

11,620,374

6,173,130

10,806,019

1992

30,950,912

190,385,530

12,406,079

18,544,833

2,531,414

11,226,701

6,328,830

10,863,967

1993

30,825,148

184,601,125

12,262,445

18,562,703

2,141,152

11,200,025

6,283,434

11,200,537

1994

30,843,087

177,178,999

12,293,339

18,549,748

2,249,317

10,956,147

6,311,114

11,326,509

1995

30,722,351

164,626,802

12,197,504

18,524,847

2,405,422

10,593,181

6,167,656

11,556,092

1996

30,544,614

159,882,807

12,109,749

18,434,865

2,206,856

10,325,208

6,294,238

11,718,312



FREQUENCIES FOR NON-NEWBORNS, NHDS, 1979-1996

DATA

YEAR

NORTH-EAST

MIDWEST

SOUTH

WEST

WHITE

BLACK

ALL OTHER

RACES

RACE

NOT STATED

1979

7,785,635

10,647,226

12,424,987

5,888,715

27,450,925

3,957,844

-

5,337,794

1980

7,868,414

10,877,714

12,982,849

6,102,582

28,484,009

4,176,172

702,456

4,468,922

1981

7,821,859

11,131,851

13,202,327

6,387,943

32,242,003

5,003,852

1,298,125

-

1982

7,847,372

10,937,996

13,435,287

6,372,700

29,879,874

4,216,328

926,139

3,571,014

1983

7,792,914

10,492,289

13,883,629

6,613,831

30,106,094

4,254,555

980,708

3,441,306

1984

7,407,768

9,899,132

13,450,674

6,404,550

28,448,523

4,265,667

1,035,836

3,412,098

1985

7,168,298

9,111,370

12,274,465

6,502,001

26,378,763

4,109,162

1,071,573

3,496,636

1986

6,955,118

8,930,808

11,892,160

6,477,829

25,363,328

4,015,423

1,100,707

3,776,457

1987

6,698,861

8,718,351

11,291,607

6,677,875

24,375,931

3,866,448

1,308,034

3,836,281

1988

7,078,483

7,832,097

10,844,990

5,390,790

23,321,644

3,828,797

1,179,155

2,816,764

1989

7,044,102

7,675,518

10,959,504

5,267,594

22,677,616

3,891,025

976,405

3,401,672

1990

6,895,148

7,620,112

11,173,053

5,099,626

21,375,856

3,611,203

958,238

4,842,642

1991

7,153,072

7,315,173

11,289,656

5,340,101

20,816,245

3,717,049

1,036,368

5,528,340

1992

7,140,865

7,121,396

11,255,745

5,432,906

20,017,886

3,692,237

1,127,549

6,113,240

1993

6,964,731

7,097,084

11,580,414

5,182,919

20,101,017

3,659,646

1,252,661

5,811,824

1994

7,128,436

7,133,439

11,310,254

5,270,958

20,003,156

3,711,210

1,351,413

5,777,308

1995

7,051,480

6,994,250

11,373,398

5,303,223

19,950,723

3,887,498

1,097,619

5,786,511

1996

6,665,339

7,106,564

11,085,190

5,687,521

19,738,155

3,779,331

1,351,228

5,675,900

 

CATEGORY OF ALL-LISTED DIAGNOSES

TOTAL DIAGNOSES

SEPTICEMIA

MALIGNANT NEOPLASMS

DIABETES

MELLITUS

PSYCHOSES

ACUTE

MYOCARDIAL

INFARCTION

ASTHMA

INJURY &

POISONING

ICD-9-CM DIAGNOSIS

CODES:

ALL CODES, EXCEPT E-CODES

038

140-208,

230-234

250

290-299

410

493

800-999

1979

86,117,260

157,201

2,887,931

2,136,178

844,025

688,256

512,964

6,390,512

1980

90,397,405

167,298

3,011,597

2,279,410

860,709

683,416

603,863

6,435,257

1981

94,364,901

179,721

3,197,975

2,395,492

965,847

772,357

627,926

6,476,685

1982

97,720,714

209,174

3,261,378

2,562,028

1,020,657

785,267

664,081

6,447,751

1983

101,968,881

256,814

3,284,594

2,774,733

1,073,172

784,672

708,607

6,340,400

1984

104,260,914

325,239

3,815,918

2,940,819

1,216,067

811,099

738,631

6,555,550

1985

100,716,114

376,900

3,739,439

2,756,904

1,336,485

870,981

742,906

6,426,072

1986

102,763,567

433,149

3,744,660

2,863,645

1,472,944

869,982

780,493

6,369,803

1987

103,431,392

438,527

3,768,126

2,901,699

1,562,034

872,189

784,536

6,353,854

1988

100,650,053

473,053

3,547,167

2,917,796

1,527,293

818,819

827,683

6,066,482

1989

101,974,483

482,964

3,588,880

2,929,710

1,568,434

797,551

835,203

5,939,040

1990

102,833,929

479,603

3,457,063

3,007,518

1,635,736

785,806

861,036

6,039,311

1991

106,907,515

516,821

3,604,767

3,304,513

1,846,023

809,233

923,066

6,059,732

1992

109,298,647

564,740

3,598,145

3,539,249

1,974,622

830,183

955,659

5,927,373

1993

112,792,664

551,449

3,486,860

3,669,661

2,218,577

839,502

999,768

6,013,845

1994

115,706,869

553,182

3,403,488

3,740,073

2,549,059

865,039

1,053,348

5,972,407

1995

118,254,675

587,651

3,472,180

3,952,279

2,544,787

857,664

1,176,094

5,965,231

1996

121,711,665

661,377

3,502,145

4,157,040

2,611,842

919,247

1,183,413

5,918,968

 

CATEGORY OF ALL-LISTED PROCEDURES

TOTAL PROCEDURES

CESAREAN SECTION

HYSTERECTOMY

CABG

PROSTATECTOMY

APPENDECTOMY

ICD-9-CM PROCEDURE CODES

ALL CODES

740-, 741-, 742-, 744-, 7499

683-687

361

602-606

470

1979

29,602,619

599,140

638,898

114,002

292,958

311,043

1980

31,411,526

619,499

649,446

137,145

334,946

290,594

1981

33,635,312

701,616

672,706

159,471

347,996

311,821

1982

34,632,285

730,339

649,998

170,117

358,306

276,638

1983

35,938,870

807,513

672,254

191,308

356,830

282,080

1984

36,155,105

812,661

664,487

202,212

361,119

294,242

1985

36,759,878

876,753

670,332

230,353

366,804

283,156

1986

38,000,321

905,616

644,188

284,464

366,713

275,192

1987

39,118,398

952,615

654,595

331,793

410,132

302,811

1988

39,191,713

933,397

578,346

352,942

357,537

272,980

1989

40,042,644

937,899

540,665

368,210

376,315

252,749

1990

40,505,676

945,330

591,066

392,111

363,789

273,725

1991

43,922,460

933,325

546,341

407,353

363,472

254,992

1992

42,627,290

920,872

579,966

468,354

352,706

260,804

1993

41,608,334

917,313

561,693

485,399

317,184

250,084

1994

40,710,173

858,417

555,987

501,210

262,551

279,774

1995

39,807,237

784,856

582,778

573,133

239,255

237,126

1996

40,397,052

835,136

590,740

598,288

202,547

262,503


FREQUENCIES FOR NEWBORN INFANTS, NHDS, 1979-1996

DATA YEAR

TOTAL

MALE

FEMALE

NORTHEAST

MIDWEST

SOUTH

WEST

SICK BABY

WELL BABY

1979

3,680,008

1,906,207

1,773,801

718,022

1,028,740

1,246,884

686,362

928,339

2,751,669

1980

3,823,935

1,949,729

1,874,206

735,271

1,043,176

1,315,209

730,279

1,008,116

2,815,819

1981

3,841,360

1,987,109

1,854,251

731,516

1,031,989

1,302,700

775,155

1,044,165

2,797,195

1982

3,926,071

2,019,681

1,906,390

733,230

1,002,579

1,404,114

786,148

1,092,820

2,833,251

1983

3,828,449

1,971,712

1,856,737

716,646

953,156

1,387,511

771,136

1,098,875

2,729,574

1984

3,857,445

2,002,965

1,854,480

688,886

938,452

1,447,418

782,689

1,166,936

2,690,509

1985

3,793,931

1,953,429

1,840,502

665,177

908,868

1,363,567

856,319

1,318,788

2,475,143

1986

3,751,460

1,953,620

1,797,840

685,520

910,701

1,250,755

904,484

1,374,505

2,376,955

1987

3,970,798

2,032,577

1,938,221

699,899

937,561

1,340,844

992,494

1,536,195

2,434,603

1988

3,732,535

1,881,926

1,850,609

736,577

887,419

1,226,961

881,578

1,511,288

2,221,247

1989

3,884,481

1,989,462

1,895,019

751,647

952,751

1,269,061

911,022

1,628,006

2,256,475

1990

3,869,089

1,981,939

1,887,150

732,771

905,076

1,323,844

907,398

1,541,839

2,327,250

1991

3,879,666

2,002,719

1,876,947

714,390

876,902

1,333,637

954,737

1,586,489

2,293,177

1992

3,688,513

1,926,108

1,762,405

684,583

806,457

1,264,024

933,449

1,510,035

2,178,478

1993

3,578,666

1,823,043

1,755,623

689,268

793,118

1,289,740

806,540

1,442,161

2,136,505

1994

3,749,285

1,934,737

1,814,548

751,139

816,617

1,315,455

866,074

1,738,328

2,010,957

1995

3,630,558

1,872,083

1,758,475

699,331

785,845

1,321,036

824,346

1,462,035

2,168,523

1996

3,925,871

1,998,799

1,927,072

645,439

825,932

1,403,164

1,051,336

1,489,640

2,436,231




This page last reviewed: Thursday, January 28, 2016
This information is provided as technical reference material. Please contact us at cwus@cdc.gov to request a simple text version of this document.
TOP