Scientific Data Documentation
Epidemiologic Followup Study, 1992 Health Care Facility Stay
ACKNOWLEDGMENTS
Overall responsibility for the data processing and the compilation and
documentation for the NHANES I Epidemiologic Followup Study (NHEFS),
1992 Health Care Facility Stay Public Use tape rested with
Michael E. Mussolino. Assistance was provided by other members of the
NHEFS data management team: Sandra T. Rothwell, Christine S. Cox,
Jennifer H. Madans, Dawn M. Scott, Madelyn A. Lane, Keith A. Zevallos,
Joel C. Kleinman, Cynthia A. Reuben, Cordell W. Golden and Jacob J. Feldman.
Special thanks are extended to Joan Cornoni-Huntley of the National
Institute on Aging (NIA) who played an important role in the development
and continuation of the NHEFS. The contribution of Westat, the contractor
who collected the data for this longitudinal study, is also gratefully
acknowledged.
The NHEFS originated as a joint project between the National Center for
Health Statistics (NCHS) and NIA. It has been funded primarily by NIA,
with additional financial support from the following components of the
National Institutes of Health (NIH) and other Public Health Service agencies:
the National Cancer Institute; the National Institute of Child Health and
Human Development; the National Heart, Lung, and Blood Institute; the
National Institute on Alcohol Abuse and Alcoholism; the National Institute
of Mental Health; the National Institute of Diabetes and Digestive and
Kidney Diseases; the National Institute of Arthritis and Musculoskeletal
and Skin Diseases; the National Institute of Allergy and Infectious
Diseases; and, the National Institute of Neurological and
Communicative Disorders and Stroke.
CONTENTS
Page
Use of NHEFS Data.................................................... 1
Errors in the Data Tapes and Survey Differences...................... 2
NHANES I Epidemiologic Followup Study, 1992.......................... 3
1992 NHEFS Health Care Facility Stay Data Tape Characteristics....... 8
1992 NHEFS Health Care Facility Stay Introduction ................... 9
Medical Coding Specifications........................................ 15
1992 NHEFS Health Care Facility Stay Public Use Tape Documentation... 21
Figure 1: Health Care Facility Record Layout......................... 43
Figure 2: Example of Matching Process and Record Status Codes........ 44
Appendix A: Record Status Codes...................................... 45
Appendix B: Numeric Codes for Reported Conditions.................... 47
USE OF NHEFS DATA
With the goal of mutual benefit, NCHS requests the cooperation of recipients
of data tapes in certain actions related to their use:
A. Any published material derived from the data should acknowledge the
National Center for Health Statistics (NCHS) as the original source.
It should also include a disclaimer which credits any analyses,
interpretations, or conclusions reached to the author (recipient of
the tape) and not to NCHS, which is responsible only for the initial
data.
B. Consumers who wish to publish a technical description of the data
will make a reasonable effort to insure that the description is not
inconsistent with that published by NCHS. This does not mean,
however, that NCHS will review such descriptions.
C. Authors should provide NCHS with a reprint of published articles which
utilize the 1992 NHEFS data. Please send reprints to :
NHEFS Data Management Staff
Division of Epidemiology
National Center for Health Statistics
Presidential Building, Room 730
6525 Belcrest Road
Hyattsville, MD 20782
ERRORS IN THE DATA TAPES AND SURVEY DIFFERENCES
The NHEFS Public Use data tapes have been subjected to a great deal of
careful editing. However, due to the large volume of data in the series,
it is likely that a small number of errors or discrepancies remain
undetected.
In general, the NHEFS data management team has not attempted to resolve
substantive data discrepancies that may exist 1) within the 1992 NHEFS data
tapes, or 2) between the 1992 NHEFS data tapes and the data tapes of the
original National Health and Nutrition Examination Survey (NHANES I) and
other NHEFS followup waves.
NHANES I EPIDEMIOLOGIC FOLLOWUP STUDY, 1992
I. NHEFS BACKGROUND INFORMATION
The NHANES I Epidemiologic Followup Study (NHEFS) is a longitudinal study
which uses as its baseline those adult persons ages 25 to 74 years who
were examined in the first National Health and Nutrition Examination Survey
(NHANES I). The NHEFS is comprised of a series of four followup surveys.
The first wave of data collection, the 1982-84 NHEFS, was conducted from
1982 to 1984 and included all persons who were between 25 and 74 years at
their NHANES I examination (n=14,407). The second wave of data collection,
the 1986 NHEFS, was conducted for members of the NHEFS cohort who were
55-74 years at their baseline examination and not known to be deceased at
the 1982-84 NHEFS (n=3,980). The third wave of data collection, the 1987
NHEFS, was conducted for the entire non-deceased NHEFS cohort (n=11,750).
The fourth wave of data collection, the 1992 NHEFS, was also conducted for
the entire non-deceased NHEFS cohort (n=11,195). This series of file
documentation describes data collected in the 1992 NHEFS.
NHANES I collected data from a national probability sample of the United
States civilian noninstitutionalized population between the ages of 1 and 74
years. The survey, which included a standardized medical examination and
questionnaires that covered various health-related topics, took place from
1971 through 1974 and was augmented by an additional national sample in
1974-75. The NHANES I sample included 20,729 persons 25 to 74 years of age,
of whom 14,407 (70 percent) completed a medical examination. The design,
content and operation of NHANES I has been described elsewhere (Vital and
Health Statistics, Series 1, Nos. 10a, 10b, and 14).
Although NHANES I provided a wealth of information on the prevalence of health
conditions and risk factors, the cross-sectional nature of the original survey
limits its usefulness for studying the effects of clinical, environmental, and
behavioral factors and in tracing the natural history of disease. Therefore, the
NHEFS was designed to investigate the association between factors measured at the
baseline and the development of specific health conditions. It originated as a
joint project between the National Center for Health Statistics (NCHS) and the
National Institute on Aging with collaboration from components of the National
Institutes of Health and other Public Health Service agencies. The 14,407
participants who were 25 to 74 years of age when they were examined in NHANES I
(1971-75) were included in the followup study population.
In the first wave, the 1982-84 NHEFS, data were collected on all 14,407 subjects
(i.e., individuals examined at NHANES I) in the cohort. Tracing of subjects
began in 1981 and data collection was conducted from 1982 to 1984. Approximately
93 percent (n=13,383) of the cohort was successfully traced by the end of the
survey period. Detailed information on the design, content, and operation of the
1982-84 NHEFS may be found in the Plan and Operation of the NHANES I
Epidemiologic Followup Study 1982-84, Vital and Health Statistics, Series 1, No.
22. The basic design of the 1982-84 NHEFS consisted of the following components:
-- tracing subjects or their proxies to a current address;
-- acquiring death certificates for deceased subjects;
-- performing in-depth interviews with the subjects or with their
proxies including, for surviving subjects, taking pulse, blood
pressure, and weight measurements of subjects; and,
-- obtaining hospital and nursing home records, including pathology
reports and electrocardiograms.
The second wave of the NHEFS, the 1986 NHEFS, was conducted to assess changes in
the health and functional status of the oldest members of the NHEFS cohort since
the last contact period. It included 5,677 subjects who were 55 years or older
at their NHANES I examination (almost 40 percent of the entire NHEFS cohort).
Data collection was restricted to 3,980 subjects aged 55 years or older at NHANES
I who were not known to be deceased at the time of the 1982-84 NHEFS, regardless
of their tracing or interview status in 1982-84. The remaining 1,697 subjects
who were deceased at the time of the 1982-84 NHEFS were excluded from additional
data collection in the 1986 NHEFS. Detailed information on the design, content,
and operation of the 1986 NHEFS may be found in the Plan and Operation of the
NHANES I Epidemiologic Followup Study 1986, Vital and Health Statistics, Series
1, No. 25.
The 1987 NHEFS, the third wave of the NHEFS, was designed to collect information
on changes in the health and functional status of the NHEFS cohort since the last
contact period. Tracing and data collection were conducted during this followup
survey only for the members of the NHEFS cohort who had not been identified as
deceased in 1982-84 or 1986 (n=11,750) regardless of their previous tracing or
interview status. The 2,657 previously deceased subjects were excluded from
additional data collection in the 1987 NHEFS. Detailed information on the
design, content and operation of the 1987 NHEFS may be found in the Plan and
Operation of the NHANES I Epidemiologic Followup Study 1987, Vital and Health
Statistics, Series 1, No. 27.
The fourth wave of NHEFS, the 1992 NHEFS, collected information on changes in the
health and functional status of the NHEFS cohort since the last contact period.
Tracing and data collection were conducted during this followup survey only for
the members of the NHEFS cohort who had not been identified as deceased in 1982-
84, 1986 or 1987 (n=11,195) regardless of their previous tracing or interview
status. The 3,212 previously deceased subjects were excluded from additional
data collection in the 1992 NHEFS.
The design and data collection procedures adopted in the 1992 NHEFS were very
similar to the ones developed in the previous surveys: subjects were traced;
subject and proxy interviews were conducted; and, health care facility abstracts
and death certificates were collected. All subjects whose vital status was not
obtained through tracing procedures were considered lost-to-followup in the 1992
NHEFS. In some cases, information about the death of a subject was obtained from
a former neighbor, a relative or another tracing source. Although this
information was noted in the subject's tracing record, he or she was considered
lost-to-followup unless the information was verified by means of a death
certificate or proxy interview. A subject's death had to be confirmed by either
a death certificate or proxy interview.
In addition to verifying the subject's vital status, the tracing process also was
used to obtain the current address of surviving subjects as well as to identify
a knowledgeable proxy respondent for deceased subjects. Respondents who were
identified and located through the tracing procedures were asked to participate
in a telephone interview. In a few cases, subjects who had been traced
successfully could not be relocated for the interview. Only their vital status
and the date when they were last traced in the 1992 survey are available.
A major difference between the 1982-84 and 1992 NHEFS waves was the manner in
which the interviews were conducted. In the 1982-84 NHEFS, the two-hour subject
interview was usually conducted in-person while, in subsequent followups the
interview was shortened to approximately 30 minutes in length and was conducted
primarily by telephone. In addition, since the questionnaire was not
administered in-person, no physical measurements were made in the 1986, 1987 or
the 1992 NHEFS.
The 1992 NHEFS interviews were conducted over the telephone using a Computer
Assisted Telephone Interviewing (CATI) system. CATI is a telephone interviewing
technique that allows the interviewer to enter the answers supplied by the
respondent directly into the computer. Thus, editing and coding time is reduced
and keypunching from a hard copy questionnaire is eliminated. A computer program
drives the questionnaire so that the correct skip patterns are followed and the
appropriate questions are displayed on the computer monitor. The skip patterns
are based on information gathered from previous data collection waves or on
responses provided during the 1992 interview. For example, certain questions on
pregnancy and menstrual history in the 1992 interview were programmed to be
skipped automatically if the subject was male or if the female subject was
interviewed previously and was 45 years of age or older at the time of that
interview. Edit and logic checks are incorporated into the data collection
system itself, thus improving the quality of the data.
As of July 19, 1993, the end of the 1992 NHEFS data collection period, 10,079
(90.0 percent) of the 11,195 members of the 1992 NHEFS cohort had been
successfully traced. Interviews were conducted for 9,281 subjects (92.1 percent
of those successfully traced). In addition, 10,535 facility stay records were
collected for 4,162 subjects using information obtained from the interview, death
certificate, or some other source. Death certificates were obtained for 1,374
(98.7 percent) of the 1,392 subjects who were known to have died since last
contact. Detailed information on the design, content, and operation of the 1992
NHEFS may be found in the Plan and Operation of the NHANES I Epidemiologic
Followup Study 1992, Vital and Health Statistics, Series 1, No. 35.
The data collected from the 1992 NHEFS are stored on four separate tapes:
1) Vital and Tracing Status tape -- contains summary information
about the status of the cohort,
2) Interview tape -- contains the data collected from the 1992
NHEFS subject and proxy interviews,
3) Mortality Data tape -- contains data abstracted from the death
certificates from all three NHEFS surveys,
4) Health Care Facility Stay tape -- contains information on
reports of stays in hospitals and non-hospital health care
facilities (e.g., nursing home, mental health care facility) as
well as information abstracted from facility medical records.
This tape is described in detail in the following pages.
1992 NHEFS HEALTH CARE FACILITY STAY DATA TAPE CHARACTERISTICS
Title: 1992 NHEFS Health Care Facility Stay Data Tape
Data Set Name: NHEFS4.HCFS.FINAL
Record Length: 429
Blocksize: 31746
Number of Records: 10,535
Recording/
Storage Media: FIXED BLOCK, EBCDIC/IBM 3480 Cartridge Tape
Created by: Office of Analysis, Epidemiology and Health Promotion
Division of Epidemiology
National Center for Health Statistics
Presidential Building, Room 730
6525 Belcrest Road
Hyattsville, Maryland 20782
1992 NHEFS HEALTH CARE FACILITY STAY INTRODUCTION
The 1992 NHEFS Health Care Facility Stay (HCFS) file contains information on all
overnight health care facility stays for members of the 1992 Followup cohort.
The 1992 Followup cohort consisted of the 11,195 subjects who were between 25 and
74 years old at their NHANES I examination and were not known to be deceased at
the time of the 1987 NHEFS. Followup cohort members who have either an interview
or a death certificate on the 1992 NHEFS data files were eligible for the health
care facility records component. The aim of this component was to develop a
complete set of health care facility (i.e., hospital and nursing home) records
for each 1992 Followup cohort member. This was accomplished by identifying all
facility stays through a series of reporting mechanisms. Facilities were
contacted to obtain copies of medical records. Reports and medical records were
then linked and the 1992 NHEFS Health Care Facility Stay file was constructed.
The procedures for obtaining reports and collecting abstracts are described
briefly, below.
The 1992 NHEFS Health Care Facility Stay file contains all information on
overnight stays that are in-scope for the 1992 NHEFS period. The in-scope period
depends upon the timing of the subject's last interview and his/her vital status.
For subjects who have not been interviewed since the NHANES I exam, the 1992 in-
scope period is from the date of the NHANES I exam to the date of the 1992
interview for surviving subjects and from the exam date to the date of death for
deceased subjects. For subjects who have had at least one followup interview
prior to the 1992 followup, the in-scope period is from the date of the last
interview (either 1982-84, 1986 or 1987) to the date of the 1992 interview for
surviving subjects and from the date of the last interview to the date of death
for deceased subjects. Stays that were reported prior to the in-scope period
were defined as out-of-scope for the 1992 survey.
Identification of Stay Reports:
Reports of overnight hospital or nursing home facility stays were obtained from
various sources. Most reports were elicited through a series of detailed
questions in section B of the interview. Generally, respondents were asked to
report all overnight facility stays since 1987 if the subject was last
interviewed in the 1987 NHEFS, since 1985 if the subject was last interviewed in
the 1986 NHEFS, since 1980 if the subject was last interviewed in the 1982-84
NHEFS, or since 1970 if the subject was last interviewed at NHANES I examination.
In addition to interview information, data on facility stays were gathered from
other reporting sources: from the death certificate, tracing sources, and other
hospital abstracts. At the conclusion of the interview, authorization was
obtained for permission to contact facilities.
Facility Data Collection:
For each stay reported during the interview, the name and address of the
facility, the reported dates of the stay, and the reason for the stay were
recorded on the hospital and health care facility chart (HHCF). A separate log
book was kept containing similar data for reports gathered from the death
certificates, tracing sources, and other hospital abstracts. All reports of
facility stays were compiled and entered into a computerized tracking system.
All reported facilities were contacted by mail and asked to review the subject's
medical records and to abstract information on exact dates of admission,
discharge and diagnoses onto standard abstract forms. In addition to completing
abstract forms, facilities were requested to submit photocopies of selected
sections of the subject's inpatient record i.e., the "facesheet", the discharge
summary and of pathology reports (for any admission where a new malignancy was
diagnosed).
Matching Records:
As the abstracts were received, they were checked against report information in
the tracking system to determine if the abstract "matched" any of the reported
stays. Date of admission and diagnosis were used as matching criteria but exact
matches on date or diagnosis were not required for a stay to be considered
matched. Abstracts were matched to reports if the reported date of admission was
within a year of the actual date of admission and if the reported reason for
admission involved the same body system as at least one of the diagnoses present
on the abstract. Cases that did not meet these specific criteria were reviewed
by NCHS staff and matched when appropriate. Since the matching rules allowed for
an admission date of up to one year before or after the reported date of
admission, some stay records are present on the file with a match record status,
an out-of-scope report date, but an in-scope date on the abstract. These records
are identified by a Type C flag in position 199 of the file.
Each record on the file represents an overnight facility stay. Therefore, one
or more records will exist for some 1992 Followup cohort subjects, while other
subjects will have no records on the file. The structure of the data file
reflects the system used to obtain and process stay information. The record is
divided into four major sections: 1) the report section, 2) the record status
section, 3) the abstract section, and 4) the related stay section. An example
of the record layout is provided in figure 1.
The subject identification number (i.e. the sample sequence number) is in
positions 1-5 on each record. This number is unique for each subject and is used
when linking the Health Care Facility Stay tape to all other NHEFS and NHANES I
Public Use Data Tapes. The total number of records per subject is found in
positions 6-7 on the file. The first section of the record is the report section
(positions 29-59 and 63-204) which contains information from the reporting source
as well as stay identification numbers assigned by NCHS. Each stay entered into
the report section is assigned a health care facility stay ID number (positions
29-33). When used in conjunction with the sample sequence number, this number
uniquely identifies each record on the file. The reported date of admission is
found in positions 47-54. This date is used in conjunction with the last
interview date to determine whether reported stays were in-scope for the NHEFS
1992 survey (position 199).
The record status section (positions 60-62) contains a code for the result of the
abstract request, i.e. match or non-match status. If a facility returned an
abstract that matched a report then a record status code of MAT (match) was
applied. A returned abstract that did not match a report but was in-scope for
the 1992 survey period was assigned the record status code of ASF (additional
stay found). A record status code of CRM (cross-referenced match) was applied
to a stay that was the continuation of a stay begun prior to the 1992 NHEFS
survey period. If an abstract was not returned, the appropriate non-match code
was assigned.
The abstract section (positions 205-379) contains the information obtained from
the facility records including actual dates of admission, discharge and
diagnoses. The diagnoses on the abstracts were coded using the ICD-9-CM
according to the medical coding specifications detailed in the following section
of this codebook. The abstract section is similar to the original 1982-84 NHEFS
Health Care Facility record file released in August 1987. The other three
sections were added when the 1986 version of the Health Care Facility Stay file
was designed. A revised 1982-84 HCFS data tape which is structured in the same
format as the 1986, 1987 and 1992 HCFS tapes has also been released.
Information will be present in one or more sections of the record depending on
whether a report was obtained, and whether an abstract was received. The
presence or absence of information in the first three sections results in three
different record profiles. Figure 2 illustrates these three profiles. The first
is the successfully matched stay record, where an abstract was received which
matched a report. Abstract information is added to the report and the code of
MAT was entered into the record status section. Complete information is
available in the first three sections of the record for these stays. The second
type occurs when an abstract was not matched to a report and, therefore, no data
is contained in the abstract section. The appropriate non-match code was entered
in the record status section. The third type of record is one which was
generated solely by the receipt of a facility abstract. This type of record
resulted when the facility returned an in-scope abstract that did not match with
any report on the tracking system. When this occurred, the abstract was entered
on the file, and stay identifiers were assigned in the report section of the
record but no other information in the report section is present. An ASF
(additional stay found) code was entered in the record status section.
In some cases requests were made to facilities for information about stays with
reported admission dates that preceded the date of the NHANES I exam (i.e., were
out-of-scope). This was done to maximize the collection of reports of hospital
or nursing home stays. Reports of stays with a reported date of admission more
than one year prior to the exam were retained on the file when they represented
the only mention of visits to a specific health care facility for a given
subject. These were flagged with a Type D in Position 199. All stays with
reported dates within the year immediately preceding the exam were kept and
flagged with a Type C in position 199.
After the receipt of information from the health care facility, it was necessary
to remove stays from the tracking system that had been out-of-scope and to
incorporate information on in-scope stays that was generated from the "out-of-
scope" reports. If an in-scope abstract was received from a facility named on
a Type D report, the in-scope stay was added to the file with a record status
code of ASF and the Type D report was deleted from the file. The Type D report
was also deleted from the file if the facility responded to the Type D request,
but sent no in-scope abstracts. In this case it was presumed that the respondent
had correctly reported the date as out-of-scope. One Type D report remains on
the final version of the file. This occurred because it was impossible to
contact the facility. These records for unconfirmed reports of out-of-scope
stays can be eliminated from analyses at the analysts' discretion. In the case
of Type C reports, if an in-scope abstract was returned which matched the Type
C report, the report was assigned a record status code of MAT (n=12). (Recall
that matching rules permitted an admission date of up to one year before or after
the reported date of admission). If the facility responded but no in-scope
abstract was received, the Type C report was also removed from the file. Again
it was assumed that the correct date had been reported and the stay was truly
out-of-scope. There are 12 Type C reports that remain on the file. These
reports were given by respondents who did not grant permission to obtain
abstracts or they involved facilities that could not be contacted, refused to
participate or did not respond. These unconfirmed reports of out-of-scope stays
are identified by the non-match status in positions 60-62 and a Type C flag in
position 199.
The final section of the record contains related stay codes (positions 380-429).
These related stay codes are used to identify stays which are contained within
other stays. This occurred most often when nursing home residents had a brief
hospital stay but then returned to the nursing home. A detailed example of the
related stay section is presented below. In panel A, a chronological history of
a subject's hospital and nursing home stays is presented in order to facilitate
the discussion of the related stay codes. This subject was admitted to the
nursing home on March 1, 1989, and discharged to the hospital on April 1, 1989.
He returned to the original nursing home on April 8 and stayed until April 22
when he required readmission to the hospital. He returned from the hospital to
the nursing home on April 25, 1989 where he remained until April 30, 1989.
Panel A: Chronological profile of hospital and nursing home stays:
Location Admission Discharge
Nursing home 03/01/89 04/01/89
Hospital 04/01/89 04/08/89
Nursing home 04/08/89 04/22/89
Hospital 04/22/89 04/25/89
Nursing home 04/25/89 04/30/89
Panel B illustrates how these stays are present in the final file. The three
nursing home stays were collapsed into one long stay with two related
hospitalizations. The related stay codes were added to demonstrate the
relationship between the hospital and nursing home stays.
Panel B: Final file layout
Variable Position:
29-33 209 210-215 216-221 380-384 385-389
Variable Name:
Stay Dis- First Second
Number Type Admit charge Related Related
40201 N. Home 03/01/89 04/30/89 40101 40102
40101 Hosp 04/01/89 04/08/89 40201
40102 Hosp 04/22/89 04/25/89 40201
MEDICAL CODING SPECIFICATIONS
Medical coding for the NHEFS 1992 data tape was based on the International
Classification of Diseases-9th Revision-Clinical Modification (ICD-9-CM). The
health care facility was asked to abstract all diagnoses and procedures onto a
special form. In most cases, a copy of the hospital discharge summary and/or
medical records facesheet was attached to the abstract. The diagnoses and
procedures listed on the discharge summary or facesheet were then compared with
those provided on the abstract form. In most instances, discrepancies were
resolved by coding the diagnoses or procedures as provided on the discharge
summary or the facesheet.
All diagnoses were coded to the highest level of specificity possible. The
fourth-digit subcategory for diagnosis and procedure codes was used whenever
possible. The fifth-digit subclassification of disease for diagnosis codes was
also used when appropriate. A three-digit ICD code was used only if it could not
be further subdivided. The following rules were used to code diagnoses and
procedures.
Rules Governing Medical Coding of Diagnoses:
All medical diagnoses listed on the health care facility abstract form or the
discharge summary are coded by trained medical coders. The coders assigned the
principal diagnosis as the condition established after study to be chiefly
responsible for occasioning the admission of the patient to the health care
facility. The admitting diagnosis is not used as the principal diagnosis unless
the admitting and discharge diagnoses are the same.
Ex: Patient admitted with a diagnosis of bronchopneumonia. After workup
and treatment, x-ray findings, etc., the patient was discharged with a
final diagnosis of bronchopneumonia. The principal diagnosis is coded
485 for bronchopneumonia.
All other diagnoses or conditions existing at the time of admission or that
developed subsequently during the stay are coded.
Ex: Patient was admitted with a diagnosis of uncontrolled diabetes
mellitus, and during the course of examination and treatment, phlebitis
was discovered. The diabetes and the phlebitis are coded.
Diagnoses documented as probable, possible, suspected, question of, suggestive
of, compatible with, or questionable are coded and prefixed with a "P".
Ex: If the diagnosis is stated possible myocardial infarction, the
diagnosis code is P410.9.
If a diagnosis is stated as "rule out" or "R/O", the condition is coded as if it
exists and the "P" prefix is not used. If a diagnosis is stated as "ruled out",
the condition is not coded.
Ex: If "R/O M.I." appears on the facesheet, the code is 410.9
If "M.I. ruled out" appears, the condition is not coded.
Hospital acquired infections, such as a "staph" infection, if documented on the
facesheet and/or discharge summary are coded. Documentation may be in the form
of a note by the infections committee, stamped notation, or a checkmark,
depending on the record format.
Malignant neoplasms are coded according to ICD-9-CM coding specifications which
indicate primary site of origin.
Injuries and poisonings are coded, where applicable, using both the nature of the
injury and the external cause of injury code (E800-E999).
Ex: Patient sustained comminuted fracture of the femur due to a fall
down stairs. Nature of injury code is 821.00 and external cause of
injury code is E880.9
"History of" conditions are not coded with the following exceptions:
Old myocardial infarction (more than 8 weeks since last occurrence)
Status post bypass surgery
Malignant neoplasm (cancer in remission or under treatment)
Old cerebrovascular accident
Sterilization
Normal pregnancy undelivered
Manipulation of an IUD
These diagnoses are coded using "V" codes and were used on a limited basis.
Recurrent malignancy codes are prefixed with an "R".
Symptoms (ICD-9-CM codes 7800-7999) were coded using the following guidelines:
1. When the only diagnosis listed on the abstract form, facesheet, and/or
discharge summary is a symptom, the symptom is coded.
Ex: The only discharge diagnosis listed is "chest pain". The code
number 786.50 (chest pain, unspecified) is assigned.
2. When a symptom is listed that is unrelated to any of the diagnoses
listed, the symptom is coded.
Ex: The discharge diagnoses listed are acute myocardial infarction,
diabetes mellitus, and hepatomegaly. The hepatomegaly is also coded.
3. When a symptom is listed and is related to a listed discharge diagnosis
the symptom is not coded.
Ex: The discharge diagnoses listed are diabetes mellitus, acute
appendicitis, severe abdominal pain. Only the diabetes and the
appendicitis are coded. The abdominal pain is not coded.
Rules Governing Medical Codes for Procedures:
The same general rules apply to coding procedures as to coding diagnoses. Medical
procedures are coded by trained medical coders from the information described on
the health care facility abstract form or the discharge summary/facesheet.
The principal procedure is the primary procedure most related to the principal
diagnosis and is performed for definitive treatment as opposed to diagnostic
and/or exploratory purposes.
Ex: Diagnosis = uterine fibroids.
Procedures = biopsy of uterus, total abdominal hysterectomy,
incidental appendectomy.
The hysterectomy is coded as the principal procedure and the
appendectomy and the biopsy are coded as secondary procedures.
All procedures documented on the discharge summary and/or facesheet are coded if
they fall into the following categories:
Biopsies (if related to the principal diagnosis and procedure or if
related to other listed diagnoses)
Surgical procedures
Cardiac catheterizations
D and C (following delivery or abortion only)
The following procedures are not coded:
Surgical approach
Operative cholangiogram
Lumbar puncture
CT scan
Endoscopy
Diagnostic D and C
Diagnostic radiology
Examination (under anesthesia, physical exam, etc.)
Manipulations
Physical therapy
Application or removal of casts, splints, etc.
Medical Coding Conventions:
Diagnostic codes--Up to ten diagnoses are coded for each hospital and nursing
home stay. The format for each diagnosis code is six positions. The following
conventions were used when entering diagnostic codes on the data tape:
1. ICD-9-CM diagnostic codes (including "V" codes) were entered beginning
with the second position of the variable field continuing through the
sixth position. There is an implied decimal point between the fourth
and fifth positions of the variable field.
2. If the diagnoses code required less than five digits the remaining tape
positions are blank.
3. Prefix codes "P" and "R" are coded in the first tape position. If the
diagnosis code has no prefix the first position is blank.
Ex. 1: _ 4 2 2 9 0 Code is 422.90
Ex. 2: _ V 7 1 1 _ Code is V71.1
Ex. 3: _ 4 3 6 _ _ Code is 436
Ex. 4: P 1 8 0 0 _ Code is P180.0
Ex. 5: R 1 7 4 9 _ Code is R174.9
4. E codes - External cause of injury codes
An external cause of injury code is provided, when applicable,
immediately after the medical diagnosis code which describes the nature
of the injury. E codes were entered on the data tape beginning in the
first position of the variable field and continuing through the fifth
position. There is an implied decimal point between the fourth and
fifth positions of the variable field. If an E code required less than
five positions the remaining positions are blank. If an E code is not
applicable (i.e. the medical diagnosis code is not a nature of injury
code) or could not be coded, the variable field is blank.
Ex. 1: E 9 0 6 1 Code is E906.1
Ex. 2: E 8 5 1 _ Code is E851
Procedure codes--Up to five procedures are coded for each health care facility
record. Each procedure code is formatted in a field containing four positions.
Procedure codes were entered beginning with the first position of the variable
field continuing through the fourth position. There is an implied decimal point
between the second and third positions of the variable field. If a procedure
code required less than four positions the remaining positions are blank.
Ex. 1: 4 2 9 2 Code is 42.92
Ex. 2: 0 3 1 _ Code is 03.1
SUBJECT INFORMATION
1-5 10535 NHANES I Sample Sequence Number
6-7 Record Count
10535 01-30 = Total number of records
Note: Each record on the file represents
an overnight stay in a health care facility
(hospital or nursing home). This variable
identifies for each subject the total
number of records on the file. It will be
the same for each record the subject has on
the file.
8-28 10535 Blank
STAY IDENTIFIERS AND REPORTED INFORMATION
ON FACILITY STAYS
Note: The report section of the record
(positions 29-59 and 63-204) contains the
information on health care facility stays
that was reported on the questionnaire, on
a death certificate, on another
hospital/nursing home abstract form, or
obtained from other sources.
(29-33) Health Care Facility Stay ID Number
Note: When used in conjunction with the
sample sequence number this number uniquely
identifies each record on the tape. It is
composed of three variables: Survey Period
Identifier, Facility Number and Stay Number
Within Facility. For example: a Stay
Number of 40102 refers to a facility stay
reported during the NHEFS 1992 wave (4) in
the first facility reported for that
subject (01) and the second admission to
that facility (02).
29 Survey Period Identifier
10535 4 = NHEFS 1992
Note: This variable identifies the survey
period in which the stay data were
collected. A facility stay reported during
the NHEFS 1992 wave will be identified with
a code number "4". All records on this
file are coded "4" in this field.
30-31 Facility Number
10535 01-91 = Hospital/nursing home number
Note: For each NHEFS subject, a two digit
number was assigned to each facility in
which a stay occurred. Thus, if a subject
had multiple stays at the same facility,
all stays will have the same facility
number.
Facility numbers were assigned
consecutively. However, due to tape
editing, there are missing numbers in the
sequence of facility numbers.
32-33 Stay Number Within Facility
10534 01-25 = Stay number
1 00 = D stay record
Note: The two digit stay numbers were
assigned to identify different stays in the
same facility. Type D stay records were
assigned a stay number of "00". A type D
stay record is defined as a stay with a
reported admission date more than one year
prior to the date of last interview (see
position 199).
Stay numbers within facilities were
assigned consecutively. However, due to
tape editing, there are missing numbers in
the sequence of stay numbers within
facilities.
34-35 Facility ID Prefix
9337 01 = Hospital
1108 02 = Nursing Home
90 03 = Out of country, don't know, not
ascertained
Note: This variable identifies the type of
facility to which the request for a stay
record was mailed.
36-46 10535 Blank
(47-54) Reported Admission Date/Range
The date of admission to a facility is
reported by month, day and year. A range
of years was coded when the respondent was
unable to recall the exact year of
admission. When the year of admission was
reported as a range, the beginning year of
the range is found in positions 51-52 and
the ending year of the range is found in
positions 53-54. Except for type D
(position 199) records the reported date of
admission is present for all source code 2
and 4 records (see position 200), and CRM
and CRX records (positions 60-62).
47-48 Reported Month of Admission
6764 01-12 = Month of admission
1340 98 = Don't know
248 99 = Not ascertained
2183 Blank = Type D (position 199), or record
status code ASF (positions 60-62),
or source code 1 or 3 (position
200) and record status code
(positions 60-62) not a cross-
referenced stay (CRM, CRX)
49-50 Reported Day of Admission
4153 01-31 = Day of admission
3951 98 = Don't know
248 99 = Not ascertained
2183 Blank = Type D (position 199), or record
status code ASF (positions 60-62),
or source code 1 or 3 (position
200) and record status code
(positions 60-62) not a cross-
referenced stay (CRM, CRX)
51-52 Reported Year of Admission or Beginning
Year of Range
7950 70-93 = Year of admission or beginning year
of range (1970-1993)
385 98 = Don't know
17 99 = Not ascertained
2183 Blank = Type D (position 199), or record
status code ASF (positions 60-62),
or source code (position 200) 1 or
3 and record status code (positions
60-62) not a cross-referenced stay
(CRM, CRX)
53-54 Reported Year of Admission - Ending Year of
Range
492 72-93 = Ending year of range (1972-1993)
10043 Blank = No range given for reported year of
admission, or type D (position
199), or record status code ASF
(positions 60-62), or source code
(position 200) 1 or 3 and record
status code (positions 60-62) not
a cross-referenced stay (CRM, CRX)
(55-59) ID Number of Cross-Referenced Facility
Status Stay
Note: The ID number on the 1982-84, 1986
or 1987 NHEFS Facility Tape (positions 29-
33) is used to reference stays in a
hospital or nursing home that began during
the 1982-84, 1986 or 1987 NHEFS periods and
which continue into the 1992 survey period.
This variable is coded only for records
with a CRM or CRX in positions 60-62 on the
1992 file.
55 Survey Period Identifier of Cross-
Referenced Facility Stay
1 1 = NHEFS 1982-84
7 2 = NHEFS 1986
189 3 = NHEFS 1987
9 S = NHEFS Supplemental HCFS file
10329 Blank = Stay not cross-referenced
56-57 Facility Number of Cross-Referenced Stay
206 01-10 = Stay number
10329 Blank = Stay not cross-referenced
58-59 Stay Number Within Facility of Cross-
Referenced Stay
206 01-03 = Stay number
10329 Blank = Stay not cross-referenced
(60-62) RECORD STATUS
Note: The record status section of the
record (positions 60-62) contains
information on the outcome of the request
for a health care facility stay.
60-62 Record Status Code
Note: See Appendix A for an explanation of
the record status codes.
10535 ANO - XRD = Record status code
(63-198) Reported Conditions and Codes
During the process of completing the
Hospital and Health Care Facility Chart
(HHCF) respondents described the conditions
that led to their overnight facility stays.
This information is included as a text
field on the stay record. Space is
allotted for the recording of up to four
reasons for the hospital or nursing home
stay (see positions 67-96, 101-130, 135-164
and 169-198).
A numeric code was assigned to each text
description to aid the researcher in the
use of this information (see positions 63-
66, 97-100, 131-134, 165-168). These
variables should be used in conjunction
with information in the abstract section,
i.e., ICD-9-CM diagnosis codes, present on
records with a record status code of MAT,
ASF or CRM. Appendix B contains a complete
description of these codes.
(63-96) First Reported Condition
63-66 Condition Code
7905 01-37 = Condition Code (See Appendix B)
2630 Blank = Source Code equal to 2 or 3 or D
stay record or Record Status Code
ASF or source code equal to 1 and
record status code not CRM.
67-96 Condition Text
7905 Description of reason for facility stay
2630 Blank = Source Code equal to 2 or 3 or D
stay record or Record Status Code
ASF or source code equal to 1 and
record status code not CRM.
(97-130) Second Reported Condition
97-100 Condition Code
2839 01-37 = Condition Code (See Appendix B)
7696 Blank = Source Code equal to 2 or 3 or D
stay record or Record Status Code
ASF or source code equal to 1 and
record status code not CRM or only
one condition reported
101-130 Condition Text
2839 Description of reason for facility stay
7696 Blank = Source Code equal to 2 or 3 or D
stay record or Record Status Code
ASF or source code equal to 1 and
record status code not CRM or only
one condition reported
(131-164) Third Reported Condition
131-134 Condition Code
562 01-37 = Condition Code (See Appendix B)
9973 Blank = Source Code equal to 2 or 3 or D
stay record or Record Status Code
ASF or source code equal to 1 and
record status code not CRM or less
than three conditions reported
135-164 Condition Text
562 Description of reason for facility stay
9973 Blank = Source Code equal to 2 or 3 or D
stay record or Record Status Code
ASF or source code equal to 1 and
record status code not CRM or less
than three conditions reported
(165-198) Fourth Reported Condition
165-168 Condition Code
122 01-37 = Condition Code (See Appendix B)
10413 Blank = Source Code equal to 2 or 3 or D
stay record or Record Status Code
ASF or source code equal to 1 and
record status code not CRM or less
than four conditions reported
169-198 Condition Text
122 Description of reason for facility stay
10413 Blank = Source Code equal to 2 or 3 or D
stay record or Record Status Code
ASF or source code equal to 1 and
record status code not CRM or less
than four conditions reported
199 Type of Stay Flag
27 C = A reported stay with admission date
up to one year prior to the date of
last interview, i.e. the NHEFS
1982-84, 1986 or 1987 if
interviewed at any followup or date
of NHANES I Examination if not
interviewed since exam.
1 D = A reported stay with admission date
more than one year prior to date of
last interview and the facility had
not been contacted previously. If
there were multiple reported stays
in the same facility that were all
type D (more than one year prior to
last interview) these stays were
consolidated into one entry in the
tracking system. If an in-scope
abstract was received in response
to a type D report, the abstract
was never matched, but assigned a
record status code of ASF
(positions 60-62). The type D
report was then removed from the
file. The type D report remaining
on the final file was not able to
be resolved.
10507 Blank = In-scope stay; a reported date of
admission after the last interview
date. This field is also blank for
record status codes of ASF, CRM or
CRX (positions 60-62).
Note: This variable identifies reported
facility stays as in-scope or out-of-scope
for the NHEFS 1992 interview period.
Reported dates of admission of don't know
(989898) or not ascertained (999999) in
positions 47-52 were considered in-scope.
200 Source of Report of Stay that Initiated
Request for Abstract
170 1 = Information from death certificate
270 2 = Information from hospital abstract
report
222 3 = Information from other source
7899 4 = Information from NHEFS 1992
interview
1974 Blank = Not a requested stay. Additional
stay information obtained from
facility (record status code ASF
positions 60-62). ASF may also be
coded as source code 3.
201-204 10535 Blank
(205-379) ABSTRACT DATA
Note: The abstract data portion of the
record (positions 205-379) contains
information obtained from an abstract form
returned by the facility. This section of
the stay record (excluding positions 207-
208) will be blank when a facility did not
return an abstract form for a stay.
205-206 Abstract Number
7996 01-27 = Number of abstract
2539 Blank = Stay reported, no abstract form
received
Note: For each subject, a two digit number
was assigned consecutively to each abstract
form received.
207-208 Total Number of Abstracts Received
10535 00-27 = Total number of abstracts received
Note: This number represents the total
number of abstracts received for each
subject. The total number is repeated on
each subject record.
209 Facility Record Type
7061 1 = Hospital
935 2 = Nursing home
2539 Blank = Stay reported, no abstract form
received
(210-215) Date of Admission
210-211 Month of Admission
7996 01-12 = Month of admission
2539 Blank = Stay reported, no abstract form
received
212-213 Day of Admission
7996 01-31 = Day of admission
2539 Blank = Stay reported, no abstract form
received
214-215 Year of Admission
7996 73-93 = Year of admission (1973-1993)
2539 Blank = Stay reported, no abstract form
received
(216-221) Date of Discharge
Note: When a subject had a brief break
in a nursing home stay not due to a
hospitalization, the nursing home stays
were combined into one long stay with the
latest discharge date assigned to the stay.
The information contained in the report and
abstract sections of the stay is from the
earliest abstract. For example: subject A
was in a nursing home from 10-31-91 to 12-
22-91. The subject was readmitted to the
same nursing home 1-3-92 and stayed until
his death 3-5-92. No information is
available for 12-22-91 to 1-3-92. These 2
stays would appear on the file as 1 stay
from 10-31-91 to 3-5-92. Length of stay
would be calculated on the entire stay (see
positions 222-225). If the break in the
nursing home was due to an interspersed
hospitalization, the nursing homes stays
were collapsed as described above and a
code was entered in the related stay
section (see positions 380-429).
216-217 Month of Discharge
7816 01-12 = Month of discharge
175 97 = Inapplicable (still at facility on
date of 1992 interview)
5 99 = Not ascertained
2539 Blank = Stay reported, no abstract form
received
218-219 Day of Discharge
7816 01-31 = Day of discharge
175 97 = Inapplicable (still at facility on
date of 1992 interview)
5 99 = Not ascertained
2539 Blank = Stay reported, no abstract form
received
220-221 Year of Discharge
7816 73-93 = Year of discharge (1973-1993)
175 97 = Inapplicable (still at facility on
date of 1992 interview)
5 99 = Not ascertained
2539 Blank = Stay reported, no abstract form
received
222-225 Length of Facility Stay
37 0000 = Died on day of admission
7779 0001-5644 = Total number of days in
facility
175 9997 = Inapplicable (still at
facility on date of 1992
interview)
5 9999 = Not ascertained
2539 Blank = Stay reported, no abstract
form received
Note: Length of stay is calculated by
subtracting the date of admission from the
date of discharge. For subjects with
nursing home stays, brief breaks were
collapsed into one continuous nursing home
stay (see positions 216-221). For
subjects with information coded in the
related stays section (see positions 380-
429) length of stay will include time spent
in other facilities.
226 Was the Patient in Cardiac Intensive Care
Unit?
699 1 = Yes
6024 2 = No
935 7 = Inapplicable (facility is a nursing
home)
338 9 = Not ascertained
2539 Blank = Stay reported, no abstract form
received
227-229 Number of Days in Cardiac Intensive Care
Unit
645 000-037 = Number of days
7297 997 = Inapplicable (position 226 =
2,7,9)
54 999 = Not ascertained
2539 Blank = Stay reported, no abstract
form received
Note: A length of stay of 0 days occurred
when a subject was admitted to the facility
and died on the day of admission.
230 Was the Patient In Other Intensive Care
Unit?
742 1 = Yes
5821 2 = No
935 7 = Inapplicable (facility is a nursing
home)
498 9 = Not ascertained
2539 Blank = Stay reported, no abstract form
received
231-233 Number of Days in Other Intensive Care Unit
642 000-081 = Number of days
7254 997 = Inapplicable (Position 230 =
2,7,9)
100 999 = Not ascertained
2539 Blank = Stay reported, no abstract
form received
Note: A length of stay of 0 days occurred
when a subject was admitted to the facility
and died on the day of admission.
234 Patient Admitted to Nursing Home From:
214 1 = Private residence
558 2 = Acute care hospital
8 3 = Chronic disease hospital
144 4 = Other nursing home
7061 7 = Inapplicable (facility is a
hospital)
11 9 = Not ascertained
2539 Blank = Stay reported, no abstract form
received
235 Disposition of Hospital Patient
4900 1 = Routine discharge/discharged home
18 2 = Left against medical advice
1096 3 = Discharged/transferred to another
facility or organization
448 4 = Discharged/referred to organized
home care service
461 5 = Died
8 6 = Not discharged/still in hospital on
the date of 1992 interview
935 7 = Inapplicable (facility is a nursing
home)
130 9 = Subject discharged, disposition not
ascertained
2539 Blank = Stay reported, no abstract form
received
236 Disposition of Nursing Home Patient
167 1 = Not discharged/still in a nursing
home on date of 1992 interview
89 2 = Discharged to private
residence/referral to organized
home care services
327 3 = Died
86 4 = Discharged to private residence/no
referral
260 5 = Transferred to another facility
7061 7 = Inapplicable (facility is a
hospital)
6 9 = Subject discharged, disposition not
ascertained
2539 Blank = Stay reported, no abstract form
received
237 Transferred to Another Health Care Facility
139 1 = Acute care hospital
108 2 = Other nursing home
1 3 = Chronic disease hospital
10 4 = Other
7736 7 = Inapplicable (Position 236 =
1,2,3,4,7 or 9)
2 9 = Not ascertained
2539 Blank = Stay reported, no abstract
form received
238-239 Number of Diagnoses
7968 01-19 = Number of diagnoses
28 99 = Not ascertained
2539 Blank = Stay reported, no abstract
form received
Note: This variable identifies the total
number of diagnoses entered on the
abstract. The number of coded diagnoses
may exceed the maximum number allowed on
the data tape (10).
240-245 Principal Diagnosis
7968 ICD-9-CM Code
28 999999 = Not ascertained
2539 Blank = Stay reported, no abstract
form received
Note: See medical coding specifications.
246-250 Principal Diagnosis E Code
571 ICD-9-CM Code
9964 Blank = Stay reported, no abstract
form received or principal
diagnosis does not require E
code
Note: See medical coding specifications.
251-256 Second Diagnosis
6950 ICD-9-CM Code
1046 999997 = Inapplicable (only one
diagnosis coded)
2539 Blank = Stay reported, no abstract
form received
Note: See medical coding specifications.
257-261 Second Diagnosis E Code
117 ICD-9-CM Code
1046 99997 = Inapplicable (only one
diagnosis coded)
9372 Blank = Stay reported, no abstract
form received or second
diagnosis does not require E
code
Note: See medical coding specifications.
262-267 Third Diagnosis
5748 ICD-9-CM Code
2248 999997 = Inapplicable (less than three
diagnoses coded)
2539 Blank = Stay reported, no abstract
form received
Note: See medical coding specifications.
268-272 Third Diagnosis E Code
112 ICD-9-CM Code
2248 99997 = Inapplicable (less than three
diagnoses coded)
8175 Blank = Stay reported, no abstract form received or third
diagnosis does not require E
code
Note: See medical coding specifications.
273-278 Fourth Diagnosis
4456 ICD-9-CM Code
3540 999997 = Inapplicable (less than four
diagnoses coded)
2539 Blank = Stay reported, no abstract
form received
Note: See medical coding specifications.
279-283 Fourth Diagnosis E Code
92 ICD-9-CM Code
3540 99997 = Inapplicable (less than four
diagnoses coded)
6903 Blank = Stay reported, no abstract
form received or fourth
diagnosis does not require
E code
Note: See medical coding specifications.
284-289 Fifth Diagnosis
3258 ICD-9-CM Code
4738 999997 = Inapplicable (less than five
diagnoses coded)
2539 Blank = Stay reported, no abstract
form received
Note: See medical coding specifications.
290-294 Fifth Diagnosis E Code
51 ICD-9-CM Code
4738 99997 = Inapplicable (less than five
diagnoses coded)
5746 Blank = Stay reported, no abstract
form received or fifth
diagnosis does not require E
code
Note: See medical coding specifications.
295-300 Sixth Diagnosis
2201 ICD-9-CM Code
5795 999997 = Inapplicable (less than six
diagnoses coded)
2539 Blank = Stay reported, no abstract
form received
Note: See medical coding specifications.
301-305 Sixth Diagnosis E Code
45 ICD-9-CM Code
5795 99997 = Inapplicable (less than six
diagnoses coded)
4695 Blank = Stay reported, no abstract
form received or sixth
diagnosis does not require E
code
Note: See medical coding specifications.
306-311 Seventh Diagnosis
1449 ICD-9-CM Code
6547 999997 = Inapplicable (less than seven
diagnoses coded)
2539 Blank = Stay reported, no abstract
form received
Note: See medical coding specifications.
312-316 Seventh Diagnosis E Code
18 ICD-9-CM Code
6547 99997 = Inapplicable (less than seven
diagnoses coded)
3970 Blank = Stay reported, no abstract
form received or seventh
diagnosis does not require E
code
Note: See medical coding specifications.
317-322 Eighth Diagnosis
924 ICD-9-CM Code
7072 999997 = Inapplicable (less than eight
diagnoses coded)
2539 Blank = Stay reported, no abstract
form received
Note: See medical coding specifications.
323-327 Eighth Diagnosis E Code
26 ICD-9-CM Code
7072 99997 = Inapplicable (less than eight
diagnoses coded)
3437 Blank = Stay reported, no abstract
form received or eighth
diagnosis does not require E
code
Note: See medical coding specifications.
328-333 Ninth Diagnosis
573 ICD-9-CM Code
7423 999997 = Inapplicable (less than nine
diagnoses coded)
2539 Blank = Stay reported, no abstract
form received
Note: See medical coding specifications.
334-338 Ninth Diagnosis E Code
17 ICD-9-CM Code
7423 99997 = Inapplicable (less than nine
diagnoses coded)
3095 Blank = Stay reported, no abstract
form received or ninth
diagnosis does not require E
code
Note: See medical coding specifications
339-344 Tenth Diagnosis
344 ICD-9-CM Code
7652 999997 = Inapplicable (less than ten
diagnoses coded)
2539 Blank = Stay reported, no abstract
form received
Note: See medical coding specifications.
345-349 Tenth Diagnosis E Code
10 ICD-9-CM Code
7652 99997 = Inapplicable (less than ten
diagnoses coded)
2873 Blank = Stay reported, no abstract
form received or tenth
diagnosis does not require E
code
Note: See medical coding specifications.
350-351 Number of Procedures
7061 00-08 = Number of procedures
935 97 = Inapplicable (facility is a nursing
home)
2539 Blank = Stay reported, no abstract form
received
Note: This variable identifies the total
number of procedures coded on the facility
abstract. The number of reported
procedures from a hospital may exceed the
maximum number of five coded on this data
tape.
352-355 First Procedure
2746 ICD-9-CM Code
5250 9997 = Inapplicable (facility is a
nursing home or no procedures
coded)
2539 Blank = Stay reported, no abstract
form received
Note: See medical coding specifications.
356-359 Second Procedure
975 ICD-9-CM Code
7021 9997 = Inapplicable (facility is a
nursing home or only one
procedure coded)
2539 Blank = Stay reported, no abstract
form received
Note: See medical coding specifications.
360-363 Third Procedure
319 ICD-9-CM Code
7677 9997 = Inapplicable (facility is a
nursing home or less than
three procedures coded)
2539 Blank = Stay reported, no abstract
form received
Note: See medical coding specifications.
364-367 Fourth Procedure
112 ICD-9-CM Code
7884 9997 = Inapplicable (facility is a
nursing home or less than four
procedures coded)
2539 Blank = Stay reported, no abstract
form received
Note: See medical coding specifications.
368-371 Fifth Procedure
45 ICD-9-CM Code
7951 9997 = Inapplicable (facility is a
nursing home or less than five
procedures coded)
2539 Blank = Stay reported, no abstract
form received
Note: See medical coding specifications.
372 Pathology Report
334 1 = Required and present
315 2 = Required and not present
6412 6 = Not required
935 7 = Inapplicable (facility is a
nursing home)
2539 Blank = Stay reported, no abstract
form received
373-379 10535 Blank
(380-429) RELATED STAY CODES
Note: Residents in nursing homes are often
admitted to hospitals during the course of
their stays in the nursing home. The
related stay section of the record cross-
links nursing home stays with interspersed
hospital stays.
In the case of nursing home records, this
set of variables identifies hospital stays
that occurred during the nursing home stay.
Up to 10 related stays can be listed.
In the case of hospital records, this set
of variables identifies the nursing home
stay within which the hospital stay
occurred. Only one related stay is
identified for hospital records.
The Related Stay is identified by its
Health Care Facility Stay ID Number
(positions 29-33) of the record for that
stay.
(380-429) ID Number(s) of Related Stay(s)
(380-384) ID of First Related Stay
380 Survey Period Identifier
605 4 = NHEFS 1992
9930 Blank = No related stays
381-382 Facility Number
605 01-91 = Hospital/nursing home number
9930 Blank = No related stays
383-384 Stay Number Within Facility
605 01-12 = Stay number
9930 Blank = No related stays
(385-389) ID of Second Related Stay
385 Survey Period Identifier
88 4 = NHEFS 1992
10447 Blank = No second related stay
386-387 Facility Number
88 01-82 = Hospital/nursing home number
10447 Blank = No second related stay
388-389 Stay Number Within Facility
88 01-13 = Stay number
10447 Blank = No second related stay
(390-394) ID of Third Related Stay
390 Survey Period Identifier
38 4 = NHEFS 1992
10497 Blank = No third related stay
391-392 Facility Number
38 01-71 = Hospital/nursing home number
10497 Blank = No third related stay
393-394 Stay Number Within Facility
38 01-14 = Stay number
10497 Blank = No third related stay
(395-399) ID of Fourth Related Stay
395 Survey Period Identifier
15 4 = NHEFS 1992
10520 Blank = No fourth related stay
396-397 Facility Number
15 01-05 = Hospital/nursing home number
10520 Blank = No fourth related stay
398-399 Stay Number Within Facility
15 01-15 = Stay number
10520 Blank = No fourth related stay
(400-404) ID of Fifth Related Stay
400 Survey Period Identifier
9 4 = NHEFS 1992
10526 Blank = No fifth related stay
401-402 Facility Number
9 02-05 = Hospital/nursing home number
10526 Blank = No fifth related stay
403-404 Stay Number Within Facility
9 02-10 = Stay number
10526 Blank = No fifth related stay
(405-409) ID of Sixth Related Stay
405 Survey Period Identifier
7 4 = NHEFS 1992
10528 Blank = No sixth related stay
406-407 Facility Number
7 02-03 = Hospital/nursing home number
10528 Blank = No sixth related stay
408-409 Stay Number Within Facility
7 01-09 = Stay number
10528 Blank = No sixth related stay
(410-414) ID of Seventh Related Stay
410 Survey Period Identifier
4 4 = NHEFS 1992
10531 Blank = No seventh related stay
411-412 Facility Number
4 02-03 = Hospital/nursing home number
10531 Blank = No seventh related stay
413-414 Stay Number Within Facility
4 02-15 = Stay number
10531 Blank = No seventh related stay
(415-419) ID of Eighth Related Stay
415 Survey Period Identifier
1 4 = NHEFS 1992
10534 Blank = No eighth related stay
416-417 Facility Number
1 02 = Hospital/nursing home number
10534 Blank = No eighth related stay
418-419 Stay Number Within Facility
1 01 = Stay number
10534 Blank = No eighth related stay
(420-424) ID of Ninth Related Stay
420 Survey Period Identifier
10535 Blank = No ninth related stay
421-422 Facility Number
10535 Blank = No ninth related stay
423-424 Stay Number Within Facility
10535 Blank = No ninth related stay
(425-429) ID of Tenth Related Stay
425 Survey Period Identifier
10535 Blank = No tenth related stay
426-427 Facility Number
10535 Blank = No tenth related stay
428-429 Stay Number Within Facility
10535 Blank = No tenth related stay
Figure 1
NHANES I Epidemiologic Followup Study (NHEFS)
Health care facility record layout
- Facility
identifiers
- Reported date
of admission
- Reported
cause of
admission
- Source of
report
Match
or
reason for
non-match
- Actual dates
admission and
discharge
- ICD-9-CM
diagnoses
- Discharge
status from
hospitals and
nursing homes
- Codes assign-
ed by NCHS to
identify
stays con-
tained within
other stays
Record Related
Report Section Status Section Abstract Section Stay Section
Figure 2
NHANES I Epidemiologic Followup Study (NHEFS)
Examples of matching process and record status codes
Record status code
Match
Report Section
Match
Abstract Section
Non-match
Report Section
Non-match code
No Abstract
received
Additional abstract found
No Report section
ASF
Abstract Section
APPENDIX A
RECORD STATUS CODES
(positions 60-62)
Code Frequency Description
ANO - 216 "Authorization Not Obtained." This code indicates
that the subject or proxy refused to sign the Medical
Authorization Form (MAF). These stays are not
requested from the reported facilities.
ASF - 2182 "Additional Stay Found." This code was assigned when
a returned in-scope abstract could not be matched to
a reported stay. This code was also assigned to in-
scope abstracts that were received as a result of an
inquiry generated by a type D report (Position 199).
The type D report was deleted from the final file.
CRM - 196 "Cross-Referenced Match." This code indicates a stay
that was begun prior to the NHEFS 1992 survey period
and continues into the 1992 survey period. For this
type of stay, the abstract is brought forward from
the previous wave. The discharge date and discharge
status information are the only positions that are
updated. The admission date is prior to the most
recent interview because this is a continuing stay.
Thus, it appears to be, but is not, out-of-scope for
1992.
CRX - 10 "Cross-Referenced Non-Match." A code assigned by
NCHS staff to close out a stay that was begun in a
previous wave and was reported to have continued into
the 1992 Survey period, yet no in-scope abstract was
received for the 1992 survey period.
FNC - 111 "Facility Never Contacted." This code was assigned
when the facility was not contacted for the following
reasons: the respondent could not recall the name of
the facility; the facility was closed; the facility
could not be located; and facility located outside
the United States.
MAT - 5618 "Record Match." This code was assigned when a
received abstract matched a reported stay. This code
was assigned to in-scope and type C (position 199)
reports, but never to type D reports. In-scope
abstracts that were received as the result of a type
D report were assigned an ASF code.
ONR - 261 "Other Non-Response." This code was assigned to a
stay when no response for the stay request had been
received from the facility by the end of the study
period.
Code Frequency Description
REF - 248 "Refused." This code was assigned if a facility
refused to send back the abstract requested. It is
record, not subject, specific. For example, a
facility may have sent some abstracts for a subject
but refused to send other abstracts for the same
subject.
XNH - 317 "Subject Never at Facility." This code was used when
the facility indicated that the patient was never
admitted to that facility.
XNS - 1299 "Other - No Stay Found." This code was assigned when
a facility responded it was unable to send abstracts
because no in-scope stays were found at the facility,
or when the facility returned the request form
without abstracts and provided no explanation for the
failure to provide them.
XRD - 77 "Record Destroyed or No Longer Available." This code
was assigned if the facility attempted to locate the
abstract but stated that it no longer existed, i.e.,
was destroyed, or lost.
APPENDIX B
NUMERIC CODES FOR REPORTED CONDITIONS ON
HEALTH CARE FACILITY STAY RECORDS
(positions 63-66, 97-100, 131-134, 165-168)
Code for reported Condition
Condition Description
01 Arthritis
02 Gout
03 Heart attack
04 Another heart condition besides heart attack
05 Coronary bypass surgery
06 Pacemaker repair, insertion and/or replacement
07 (Not assigned in 1987 or 1992 files, see notes below)
08 Stroke or CVA (cerebrovascular accident)
09 Diabetes
10 High blood pressure
11 Cancer and/or cancer treatment other than skin cancer
1101 Malignant melanoma
1102 Skin cancer other than malignant melanoma
12 Fractured hip
13 Another type of bone fracture besides a hip fracture
14 (Not assigned in 1987 or 1992 files, see notes below)
15 Surgery
16 Don't know
17 Not ascertained
18 Tests/observation/x-rays/physical exam
19 Digestive/endocrine condition
20 Respiratory condition (including influenza and
pneumonia)
21 Infection
22 Kidney/bladder/urinary condition
23 Debility/pain
24 Male reproductive condition
25 Musculoskeletal problem or injury other than a
fracture
26 Circulatory condition
27 Female reproductive condition
28 Mental illness
29 Neurologic condition
30 Nutritional condition or dehydration
31 Bleeding or blood disorder
32 Skin condition
33 Condition not elsewhere coded
34 Admission to a facility other than an acute care
hospital
35 In a facility at time of death
36 Cataracts
3603 Eye problem other than cataracts, detached retina or
glaucoma
37 A fall
APPENDIX B (continued)
Guidelines for Use of Numeric Codes for Reported Conditions
Background
During the process of completing the Hospital and Health Care Facility
(HHCF) chart respondents were asked to describe the conditions that led
to their facility stays and this information is included as a text field
on the stay record. The text portion of the reported condition contains
standard nomenclature for certain conditions (see Type A conditions below)
or the respondent's own words. If necessary the respondent's descriptions
was edited to fit into the 30 positions available in the record. A
numeric code was also assigned to each description. This was done so that
users would not have to deal with alphabetic description fields when
investigating reasons for facility stays. Space is allotted on the report
section of the facility stay record for recording of up to four reasons
for the hospitalization or nursing home stay (positions 63-198 of the HCFS
record).
Note that codes "07" and "14" are not included in the coding structure for
the 1987 and 1992 files. These codes had been assigned to conditions in
the 1982-84 and 1986 followups. The 1987 and 1992 followup questionnaires
differ from the earlier versions and sufficient information was not
collected to assign these codes.
Reported conditions and their associated codes can be divided into six
types depending on where in the interview the stay was reported and the
amount of information obtained: specific conditions included in Section
B of the interview (Type A); conditions which are well-defined but for
which no question exists in Section B of the interview (Type B); unknown
conditions (Type C); conditions about which there is no specific question
in Section B but for which sufficient information is available to
attribute them to disorders of a major body system (Type D); conditions
that are broadly defined and/or cannot be attributed to a single major
body system (Type E); and conditions that cannot be classified into any
of the above categories (Type F). Each condition type, the associated
codes and the rules for assigning the reported conditions to the
categories of the coding structure are described in detail below.
Type A - Conditions about which the respondent was asked in section B of
the interview. For example, if a respondent answered "yes" to
question B-17 ("Were you hospitalized for your arthritis?"),
then a condition code of "01" and a text field containing
"arthritis" would be included on the facility stay record.
Type A conditions are:
01 Arthritis (B-17)
02 Gout (B-17)
03 Heart attack (B-23)
04 Other heart conditions (B-24)
05 Coronary bypass surgery (B-27)
06 Procedures for pacemakers (B-29)
08 Stroke (B-35)
09 Diabetes (B-42)
10 High blood pressure (B-52)
11 Cancer (B-66) other than skin cancer
1101 Malignant Melanoma (B-60)
1102 Skin cancer (B-63) other than malignant melanoma
12 Fractured hip (B-80)
20 Pneumonia, bronchitis and influenza (B-90)
Note: this code is also found under Type D
because other respiratory conditions are
also coded to category 20
22 Kidney, bladder or urinary problem (B-97)
34 Care in non-acute care facility (B-121)
35 In a facility at death (B-127)
36 Cataracts (B-108)
37 A fall (B-89)
Complete agreement between responses to the questions in section B and
Type A condition codes on the facility stay file should not be expected.
There are several reasons for a lack of agreement between these two data
sources.
First, the respondent may report a facility stay for a given condition in
the interview and yet no facility stay record containing the condition may
appear on the HCFS file. This would result if: (1) it was determined that
the hospitalization did not last overnight causing the stay to be deleted
from the HCFS file; or (2) the reported stay was found to be "out-of-
scope". (See the introduction to this codebook and the Plan and Operation
for definitions of out-of-scope stays.)
Second, data may be inconsistent between the interview and the HCFS file
if the respondent remembered and reported a condition after responding to
the corresponding question in Section B of the interview. This tended to
occur at the time the interviewer was recording information on the HHCF
chart. For example, while recording information on a stay for high blood
pressure, the respondent may add that he/she was also hospitalized at that
time for a heart condition. The respondent may not have reported the
hospitalization when asked about heart conditions in question B-24 and the
Section B information may not have been updated to reflect this additional
condition. However, heart condition would appear on the HCFS file.
Type B - Conditions which do not have a corresponding question in Section
B of the interview but for which sufficient descriptive information
is available to allow them to be easily coded:
13 Bone fracture
18 Tests and observation
Type C - Unknown conditions:
16 Don't know
17 Not ascertained
Type D - Conditions for which there is not a specific question in Section
B of the interview but which can be attributed to disorders of a
major body system:
19 The digestive/endocrine system
20 The respiratory system
Note: this code is also found under Type A
because the specific question about pneumonia,
bronchitis and influenza (B-90) is coded to the
general category
24 The male reproductive system
25 The musculoskeletal system
26 The circulatory system (except strokes)
27 The female reproductive system
29 Neurologic disorders
31 Blood disorder/bleeding
32 Skin problem
3603 Eye problem (except cataracts, detached retina or glaucoma)
Type E - Conditions which are broadly defined or are attributed to
problems of more than one major body system:
15 Surgery
21 Infections
23 Debility and pain
28 Mental illness
30 Nutrition and dehydration
Type F - All conditions that cannot be assigned to one of the above codes:
33 Other conditions
Additional information on reasons for a facility stay is available in the
abstract section of the record (positions 205-379) if an abstract has been
matched to the report. In general information from the abstract is
considered a more accurate determination of the conditions associated with
the stay than are the reported conditions. The condition codes in the
report section of stay records do provide useful information in the
absence of a medical abstract. Both flexibility and caution should be
exercised when selecting stays based on these codes. In order to help the
analyst use these condition codes effectively, a description of the code
assignment procedure along with an example is provided.
Rules for Assignment
The numeric codes were assigned to the respondent's non-technical
descriptions by trained medical coders. In order to minimize variation
among the coders assigning these codes, precedence rules were defined.
Generally, a condition was coded to the most specific category in which
it could be placed. The assignment rules are described below in priority
order, e.g. Rule 2 was used only if Rule 1 did not apply and so forth.
Rule 1: If a condition was one about which there was a
specific question in Section B of the interview, the
code appropriate for that question was assigned.
(Type A conditions)
Rule 2: If the textual description could be coded to a
narrowly defined condition not referenced in Section
B or to the unknown category, the appropriate Type B
or Type C code was assigned.
Rule 3: Conditions that could not be coded to a specific
question but could be coded to a major body system
were assigned the appropriate Type D code.
Rule 4: General descriptions, symptoms and conditions not
coded by rules 1 through 3 were coded at the
discretion of the medical coder, again with emphasis
on as much specificity as possible. For example,
"HEADACHES, BRAIN TUMOR" would be coded to "29 -
Neurologic disorders", not to "23 - Debility and
pain". (Type D or Type E conditions)
Rule 5: Everything that could not be assigned a code after
applying the above rules was coded to "33 - Other
conditions". (Type F conditions)
Considerations for the data user
These precedence rules were used for all four followups. However, since
the questionnaires used in each followup differed slightly, the assignment
of codes also differed. Questions about specific conditions were not
always included in all four questionnaires. For example, Question B-63
in the 1986 interview asked about overnight stays for surgery making
condition code "15 -Surgery" a Type A condition in the 1986 followup.
There is no similar question in the 1982-84, 1987 or 1992 interviews,
therefore, surgery is a Type E condition in the 1982-84, 1987 and 1992
files. In other cases, groups of conditions are combined into one
question on one questionnaire but asked separately on another.
For example, T.I.A.'s and other strokes are combined in one question
in 1987 and 1992. Since it was not possible to separate reports of
T.I.A.'s from other strokes in the 1987 and 1992 files, there are no
conditions assigned to codes "07" in these files. There are reports
assigned to "07" in the 1982-84 and 1986 files since separate T.I.A.
and stroke questions were asked. An attempt was made to include as
much detail in the code as possible. The questionnaire in the 1982-84
followup included enough detail to separate specific digestive
conditions, such as colitis and gallbladder problems, from the general
category of digestive disorders. Therefore, the 1982-84 HCFS data file,
includes sub-codes under "19 - Digestive/endocrine system". Thus,
analysts interested in colitis can identify cases from the reported
condition section of the 1982-84 file but not from the 1986, 1987 or
1992 files. However, all files can be used to identify cases of the
digestive/endocrine system in general. The analyst should refer to the
questionnaire and the condition coding structure in the HCFS data tape
codebook for the period of interest in order to obtain the maximal
amount of information available.
In using the condition codes to select records of interest, two
characteristics of the coding structure should be considered: (1) the
condition of interest may be found under more than one numeric code and
(2) each numeric code covers more than one condition.
To illustrate the first situation, consider a search for all reported
stays with breast biopsies. A respondent might report a breast biopsy
in response to the question relating to cancer and cancer treatment. In
this case the textual field would contain a description such as "BIOPSY
OF RIGHT BREAST" and the numeric code assigned would be 11 (indicating a
response to the cancer stay question). Breast biopsies could also be
reported in response to the surgery question in the 1986 followup and be
assigned the code of 15. If the biopsy was reported in response to
question B-112 on the 1992 questionnaire, "Have you stayed in a hospital
for any other reason...?", it would be assigned to code 18 - Tests and
observation". To identify breast biopsy cases it would be necessary to
search the alphabetic fields for codes 11, 15 and 18. In addition, the
reports of breast biopsies include several wording variations, for
example, "BREAST BIOPSY", "BIOPSY OF BREAST". The analysts needs to
investigate all possible wordings.
To illustrate the second situation, consider code 18 - "Tests and
observation". Over 250 different verbal descriptions have been coded to
this category including a variety of radiological procedures, surgeries
and physical examinations. Selecting just on code 18 will result in a
wide variety of procedures. Those of a specific interest need to be
identified by the textual description.
Analysts who wish to use these reports, should print and review all the
reported condition codes and alphabetic descriptions from the Health Care
Facility Stay data files. Such a review will aid in (1) finding all the
numeric condition codes under which the condition of interest will be
found and (2) insuring that, within any numeric condition code, only the
reports of interest will be selected.
Finally, the condition codes in the report section should be used in
conjunction with the information in the abstract section if it is
available. Returned abstracts were matched to reports if one of the
reported conditions matched one of the discharge diagnoses on the
abstract. Other conditions reported for the same stay may or may not be
confirmed in the matched medical abstract. If the condition of interest
is not indicated as a discharge diagnosis on the medical record, the
analyst may not want to accept the reported condition as a reason for the
stay. Similarly, conditions may be listed as discharge diagnoses that do
not appear on the report section. See the introduction to this codebook
for a description of the match criteria.
