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Scientific Data Documentation
National Hospital Ambulatory Medical Care Survey, 1994DSN: CC37.NHAMCS94.EMRGENCY (Emergency Department File) CC37.NHAMCS94.OPATIENT (Out-Patient Department File) DESCRIPTION OF THE NATIONAL HOSPITAL AMBULATORY MEDICAL CARE SURVEY A. INTRODUCTION The National Hospital Ambulatory Medical Care Survey (NHAMCS) was initiated to learn more about the ambulatory care rendered in hospital emergency and outpatient departments in the United States. Ambulatory medical care is the predominant method of providing health care services in the United States (reference 1). Since 1973, data on ambulatory patient visits to physicians' offices have been collected through the National Ambulatory Medical Care Survey (NAMCS). However, visits to hospital emergency and outpatient departments, which represent a significant portion of total ambulatory medical care, are not included in the NAMCS (reference 2). Furthermore, hospital ambulatory patients are known to differ from office patients in their demographic characteristics and are also thought to differ in medical aspects (reference 3). Therefore, the omission of hospital ambulatory care from the ambulatory medical care database leaves a significant gap in coverage and limits the utility of the current NAMCS data. The NHAMCS fills this data gap. The NHAMCS was endorsed by the American Hospital Association, the Emergency Nurses Association, and the American College of Emergency Physicians. A complete description of the NHAMCS is contained in the publication entitled, "Plan and Operation of the National Hospital Ambulatory Medical Care Survey" (reference 4). This data file comprises the data collected by the NHAMCS in 1994. The survey was conducted by the Ambulatory Care Statistics Branch of the National Center for Health Statistics, Centers for Disease Control and Prevention. The NHAMCS provides data from samples of patient records selected from the emergency departments (EDs) and outpatient departments (OPDs) of a national sample of hospitals. The national estimates produced from these studies describe the utilization of hospital ambulatory medical care services in the United States. In 1994, there were 26,547 Patient Record forms provided by 418 EDs and 29,095 Patient Record forms provided by 260 OPDs that participated in the survey. Both data files, ED and OPD, are included in this product. Additional information on data findings from the 1994 NHAMCS has been published (references 5 and 6). There are two important points relative to analyzing data from these files that should be noted: 1. Data users should be fully aware of the importance of the "patient visit weight" and how it must be used. Information about the patient visit weight is presented on page 16. If more information is needed, the staff of the Ambulatory Care Statistics Branch can be consulted by calling (301) 436-7132 during regular working hours. 2. Users should also be aware of the reliability or unreliability of certain estimates, particularly the smaller estimates. The National Center for Health Statistics, which conducts many health surveys of the American people, considers an estimate to be reliable if it has a relative standard error of 30% or less, that is, the standard error is not greater than 30% of the estimate of interest. Therefore, it is important to know the value of the lowest possible estimate in this survey that is considered reliable, so as not to present data in a journal article or paper that may be unreliable. Most data users can obtain an adequate working knowledge of the relative standard error from the information presented in the section, "Relative Standard Errors." If you would like more information, do not hesitate to consult the staff of the Ambulatory Care Statistics Branch. B. SAMPLE DESIGN The 1994 NHAMCS included a national probability sample of visits to the emergency and outpatient departments of noninstitutional general and short- stay hospitals, exclusive of Federal, military, and Veterans Administration hospitals, located in the 50 states and the District of Columbia. The NHAMCS was designed to provide estimates based on the following priority of survey objectives: United States; region; emergency and outpatient departments; and type of ownership. The NHAMCS used a four-stage probability design with samples of primary sampling units (PSUs), hospitals within PSUs, clinics within hospitals, and patient visits within clinics. Each stage of sampling is described below. 1. Primary Sampling Units (PSUs) A PSU consists of a county, a group of counties, county equivalents (such as parishes and independent cities), towns, townships, minor civil divisions for some PSUs in New England), or a metropolitan statistical area (MSA). MSAs were defined by the U.S. Office of Management and Budget on the basis of the 1980 Census. The first-stage sample consisted of 112 PSUs that comprised a probability subsample of the PSUs used in the 1985-94 NHIS. The NHAMCS PSU sample included with certainty the 26 NHIS PSUs with the largest popula- tions. In addition, the NHAMCS sample included one-half of the next 26 largest PSUs, and one PSU from each of the 73 PSU strata formed from the remaining PSUs for the NHIS sample. The NHIS PSU sample was selected from approximately 1,900 geographically defined PSUs that covered the 50 States and the District of Columbia. The 1,900 PSUs were stratified by socioeconomic and demographic variables and then selected with a probability proportional to their size. Stratification was done within four geographical regions by MSA or non-MSA status. A detailed description of the 1985-94 NHIS PSU sample design is available (reference 7). 2. Hospitals The sampling frame for the 1994 NHAMCS was compiled from the hospitals listed on the April 1991 SMG Hospital Market Data Base. Hospitals with an average length of stay for all patients of less than 30 days (short-stay) or hospitals whose specialty was general (medical or surgical) or children's general were eligible for the NHAMCS. Excluded were Federal hospitals, hospital units of institutions, and hospitals with less than six beds staffed for patient use. The SMG Hospital Market Data Base contained 6,249 hospitals that met these eligibility criteria. Of the eligible hospitals, 5,582 (89 percent) had emergency departments (EDs) and 5,654 (90 percent) had outpatient departments (OPDs). Hospitals were defined to have an ED if the hospital file indicated the presence of such a unit or if the file indicated a non-zero number of visits to such a unit. A similar rule was used to define the presence of an OPD. Hospitals were classified into four classes: those with only an ED; those with an ED and an OPD; those with only an OPD; and those with neither an ED nor an OPD. Hospitals in the last class were considered as a separate stratum and a small sample (50 hospitals) was selected from this stratum to allow for estimation to the total universe of eligible hospitals and the opening and closing of EDs and OPDs in the sample hospitals. All hospitals in non-certainty PSUs with five or fewer hospitals were selected with certainty. There were 149 hospitals in 55 PSUs in this category. In non-certainty PSUs with more than five hospitals, hospitals were stratified by hospital class; type of ownership (not-for-profit, non-Federal government, and for-profit); and hospital size. Hospital size was measured by the combined volume of ED and OPD visits. From the stratified hospital list, five hospitals were selected in each PSU with probability proportional to the number of ED and OPD patient visits. A total of 161 hospitals was selected from this group. In the certainty PSUs, hospitals were stratified by region, hospital class, ownership, and size. From the stratified hospital list, 240 hospitals were selected based on probability proportional to size. A sample of 50 hospitals was selected from the 427 hospitals that had neither an ED nor an OPD. The hospital selections were made so that each hospital would be chosen only once to avoid multiple inclusion of very large hospitals. A fixed panel of 600 hospitals was selected for the NHAMCS sample; 550 hospitals had an ED and/or an OPD and 50 hospitals had neither an ED nor an OPD. To preclude hospitals participating during the same time period each year, the sample of 600 hospitals was randomly divided into 16 subsets of approximately equal size. Each of the subsets was assigned to 1 of 16 4-week reporting periods beginning December 2, 1991, which continue to rotate throughout each survey year. Therefore, the entire sample does not partici- pate in a given year, and each hospital is inducted approximately once every 15 months. The 1994 NHAMCS included data collected from December 27, 1993 through December 25, 1994, and consisted of a sample of 489 hospitals. Of the 489 hospitals in the 1994 NHAMCS, 443 were in scope or eligible to participate in the survey. The hospital response rate for the NHAMCS during this period was 95 percent. Table I displays the response rates for the 489 hospitals selected in the sample. 3. Outpatient Clinics and Emergency Service Areas Within each hospital, either all outpatient clinics and emergency service areas or a sample of such units were selected. Clinics were in scope if ambulatory medical care was provided under the supervision of a physician and under the auspices of the hospital. Clinics were required to be "organized" in the sense that services were offered at established locations and schedules. Clinics where only ancillary services were provided or other settings in which physician services were not typically provided were out of scope. In addition, freestanding clinics were out of scope since they are included in the NAMCS, and ambulatory surgery centers, whether in hospitals or freestanding, were out of scope since they were to be included in the National Survey of Ambulatory Surgery which was first fielded in 1994. A list of in scope and out of scope clinics is provided in the section, "Definition of Terms Used in the Survey." The OPD clinic definition excluded the "hospital as landlord" arrangement in which the hospital only rented space to a physician group and was not otherwise involved in the delivery of services. These physicians are considered office-based and are currently included in the NAMCS. Emergency services provided under the "hospital as landlord" arrangement, however, were eligible for the study. An emergency department was in scope if it was staffed 24 hours a day. If an in scope emergency department had an emergency service area that was open less than 24 hours a day, then it was included under the emergency department. If a hospital had an emergency department that was staffed less than 24 hours a day, then it was considered an outpatient clinic. Hospitals may define the term "separate clinic" differently, for example, by physical location within the hospital, by staff providing the services, by specialty or subspecialty, by schedules, or by patients' source of payment. Because of these differences, "separate clinics" in the NHAMCS were defined as the smallest administrative units for which the hospital kept patient volume statistics. During the visit by a field representative to induct a hospital into the survey, a list of all emergency service areas and outpatient clinics was obtained from the sample hospital. Each outpatient department clinic's function, specialty, and expected number of visits during the assigned reporting period were also collected. If there were five or fewer clinic sampling units, then all were included in the sample. Table I. Distribution of hospitals in the National Hospital Ambulatory Medical Care Survey (NHAMCS) by reporting period and response status: United States, 1994 ___________________________________________________________________________ Reporting Period Response Status Total 12 13 14 15 16 01 ___________________________________________________________________________ SAMPLE SIZE 489 37 37 37 38 38 38 A. Complete 403 26 29 31 32 34 36 B. Partial complete 16 2 1 1 2 1 0 C. Out of Scope 47 6 6 4 2 2 2 Federal Hospital 1 0 0 0 0 0 0 No ED or OPD 29 3 5 1 1 2 2 Other 17 3 1 1 2 1 0 D. Refused 23 3 1 1 2 1 0 E. Response Rate 95% 90% 97% 97% 94% 97% 100% _____________________________________________________________________________ Response rate is sum of (A) and (B) divided by the sum of (A), (B), and (D). Reporting Period Dates: 12 = Dec. 27, 1993 - Jan. 23, 1994 13 = Jan. 24 - Feb. 20, 1994 14 = Feb. 21 - Mar. 20, 1994 15 = Mar. 21 - Apr. 17, 1994 16 = Apr. 18 - May 15, 1994 01 = May 16 - June 12, 1994 02 = June 13 - July 10, 1994 03 = July 11 - Aug. 7, 1994 04 = Aug. 8 - Sep. 4, 1994 05 = Sep. 5 - Oct. 2, 1994 06 = Oct. 3 - Oct. 30, 1994 07 = Oct. 31 - Nov. 27, 1994 08 = Nov. 28 - Dec. 25, 1994 ___________________________________________________________________ Reporting Period Response Status 02 03 04 05 06 07 08 ___________________________________________________________________ SAMPLE SIZE 38 38 38 37 38 37 38 A. Complete 26 32 31 30 33 32 31 B. Partial Complete 4 1 2 0 0 0 2 C. Out of Scope 4 3 3 5 2 3 5 Federal Hospital 0 0 0 0 0 0 1 No ED or OPD 2 1 2 4 1 3 2 Other 2 2 1 1 1 0 2 D. Refused 4 2 2 2 3 2 0 E. Response Rate 88% 94% 94% 94% 92% 94% 100% ____________________________________________________________________ If a sample hospital had more than five clinic sampling units, then five units were randomly selected as follows: The individual clinics were listed first by five clinic categories: general medicine, surgery, pediatrics, obstetrics/gynecology, and other. Within each category, clinics were listed in order of clinic size, from smallest to largest. Clinic size was defined as the expected number of patient visits during the assigned 4-week reporting period. Within each clinic group, if a clinic expected fewer than 30 visits, it was grouped with one or more other clinics to form a sampling unit. Over 90 percent of the clinics were large enough to form their own sampling unit. After grouping the clinics into sampling units, five of these sampling units were selected based on probability proportional to the size of the sampling unit. If clinic sampling was required, the sampling was completed by Census headquarters staff in Washington, DC. The 1994 NHAMCS included 873 clinics from 260 outpatient departments. The emergency department was treated as a separate stratum, and all emergency service areas were selected with certainty. In the rare instance that a sample hospital had more than five emergency service areas, a sample of five emergency service areas was selected with probability proportional to the expected number of visits to each emergency service area. The 1994 NHAMCS included 457 emergency service areas from 418 emergency departments. 4. Visits The basic sampling unit for the NHAMCS is the patient visit or encounter. Only visits made in the United States by patients to EDs and OPDs of nonfederal, short-stay, or general hospitals were included in the 1994 NHAMCS. Within emergency service areas or outpatient department clinics, patient visits were systematically selected over a randomly assigned 4-week reporting period. A visit was defined as a direct, personal exchange between a patient and a physician, or a staff member acting under a physician's direction, for the purpose of seeking care and rendering health services. Visits solely for administrative purposes, such as payment of a bill, and visits in which no medical care was provided, such as visits to deliver a specimen, were out of scope. The target numbers of Patient Record forms to be completed for EDs and OPDs were 50 and 150, respectively. In clinics with volumes higher than these desired figures, visits were sampled by a systematic procedure which selected every nth visit after a random start. Visit sampling rates were determined from the expected number of patients to be seen during the reporting period and the desired number of completed Patient Record forms. During the 1994 NHAMCS, Patient Record forms were completed for 26,547 ED visits and 29,095 OPD visits. Specifications for visit sampling called for a maximum sampling rate of 1 in 20 visits or a maximum of 200 visits, whichever yielded the smaller sample size. C. DATA COLLECTION PROCEDURES 1. Field Training The Bureau of the Census was the data collection agent for the 1994 NHAMCS. Census Headquarters staff were responsible for overseeing the data collection process, training the Census Regional Office staff, and writing the field manual. Regional Office staff were responsible for training the field representatives and monitoring hospital data collection activities. Field representative training included approximately 4 hours of self-study and 1 1/2 to 2 days of classroom training. Field representatives inducted the hospitals and trained the hospital staff in visit sampling and completion of the Patient Record forms. 2. Hospital Induction Approximately 3 months prior to the hospital's assigned reporting period, NCHS sent a personally signed introductory letter from the Director of NCHS to the hospital administrator or chief executive officer of each sampled hospital. The names of the hospital officials were obtained from the American Hospital Association (AHA) Guide To Health Care. In addition to the introductory letter, NCHS also enclosed endorsement letters from the AHA, the Emergency Nurses Association, and the American College of Emergency Physicians to emphasize the importance of the study to the medical community. Approximately one week after the mailing of the introductory letter, the Census field representative called the hospital administrator to arrange for an appointment to further explain the study and to verify hospital eligibil- ity for the survey. Earlier studies indicated that the three-month lead time was necessary to obtain a meeting with the administrator, gain hospital approval, collect the required information about the hospital's ambulatory care services, develop the sampling plan, and train participating hospital staff (references 8 and 9). 3. Outpatient Clinic and Emergency Service Area Induction After the initial visit and the development of the sampling plan, the field representative contacted the hospital coordinator to arrange for induction of the sample emergency service areas and outpatient clinics and for instruction of the hospital staff. At these visits, the field representative described the purpose and use of the survey data, explained the data collection process, including the visit sampling procedures, and presented the Patient Record forms. 4. Data Collection The actual visit sampling and data collection for the NHAMCS was primarily the responsibility of hospital staff. This procedure was chosen for several reasons. First, the lack of a standard form or record coversheet in hospitals and the individuality of the hospital recordkeeping made field representative training difficult. Second, for confidentiality reasons, numerous hospitals did not want the field representatives to review patient logs or see actual medical records. Third, hospital staffs were better qualified to abstract data since they were familiar with the medical terms and coding, knew the recordkeeping systems, and could complete the Patient Record forms at or near the time of the visit when the information was the most complete and easiest to retrieve. Hospital staff responsible for completing the Patient Record forms were instructed in how to complete each item by the field representatives. Separate instruction booklets for emergency service areas and outpatient department clinics were prepared and provided to guide hospital staff in this task. These booklets provided an overview of the survey, sampling instructions, instructions for completing the Patient Record forms, and definitions. A brief, one page Patient Record form consisting of two sections was completed for each sample visit. To account for the differences in emergency and outpatient care, different Patient Record forms were developed for each of these settings. The top section of each Patient Record form, which contains the patient's name and record number, was separated from the bottom section by a perforation running across the page. The top section remained attached to the bottom until the entire Patient Record form was completed. To ensure confidentiality, before collecting the completed Patient Record forms, the top section was detached and given to the hospital staff. The field representatives instructed hospital staff to keep this portion for a period of four weeks, in case it was necessary to retrieve missing information or clarify information that had been recorded. The Patient Record forms were patterned after the NAMCS and can be completed in 2-3 minutes. The OPD Patient Record form most closely resembles the NAMCS Patient Record form, while the ED Patient Record form has been designed to reflect the type of care provided in that setting. Terms and definitions relating to the Patient Record forms are included in the section, "Patient Record Forms - Instructions and Definitions." D. FIELD QUALITY CONTROL The field representative visited the sampled emergency service areas and clinics each week during the data collection period and maintained telephone contact with the hospital staff involved in the data collection effort. The field representative reviewed the log or other records used for visit sampling to determine if any cases were missing and also edited completed forms for missing data. Attempts were made to retrieve both missing cases and missing data on specific cases, either by consulting with the appropriate hospital staff or by reviewing the pertinent medical records. On the final visit, the field representative collected the remaining Patient Record forms and obtained or verified the total count of visits occurring during the reporting period by reviewing the log used for sample selection or by obtaining counts directly from hospital staff. Because this information was critical to the estimation process, extensive effort was made to ensure the accuracy of this number. At the end of the hospital's reporting period the field representative sent the administrator a personalized "Thank You" letter. E. CONFIDENTIALITY Assurance of confidentiality was provided to all hospitals according to Section 308 (d) of the Public Health Service Act (42 USC 242m). Strict procedures were utilized to prevent disclosure of NHAMCS data. All information which could identify the hospital or its facilities was confidential and was seen only by persons engaged in the NHAMCS, and was not disclosed or released to others for any other purpose. Names or other identifying information for individual patients were not removed from the hospitals or individual facilities. F. DATA PROCESSING 1. Edits In addition to followups for missing and inconsistent data made by the field staff, numerous clerical edits were performed on data received for central data processing. Detailed editing instructions were provided to manually review the patient records and to reclassify or recode "other" entries. Computer edits for code ranges and inconsistencies were also performed. 2. Quality control All medical and drug coding and keying operations were subject to quality control procedures. Quality control for the medical and drug coding operation, as well as straight-key items, involved a two-way 10-percent independent verification procedure. As an additional quality control, all Patient Record forms with differences between coders or with illegible entries for the reason for visit, procedures, diagnosis, E-code (cause of injury), and medication items were reviewed and adjudicated at NCHS. The average keying error rate for nonmedical items was 0.5 percent. For items which required medical coding, discrepancy rates averaged less than 5 percent. 3. Imputations Item nonresponse was quite low, 4 percent or less, for all data items with the following exceptions: race (11 percent), ethnicity (22 percent), urgency [item 13 on the ED form] (5 percent) and whether the visit was alcohol- or drug-related, [item 14 on the ED form] (6 percent). Incomplete data items were imputed using a "hot deck" procedure by assigning a value from a randomly selected Patient Record form with similar characteristics. For item 13 (urgency) on the ED Patient Record form, the sorting used was ED size by the 3-digit ICD-9-CM code for principal diagnosis. For other ED variables [i.e., item 4 (date of birth), item 5 (sex), item 6 (race), item 7 (ethnicity), item 14 (visit alcohol- or drug-related), item 18 (disposition), and item 19 (providers)], the sort used was ED size by urgency by the 3-digit ICD-9-CM code for principal diagnosis. ED size was determined from the entry on the NHAMCS-101/U (Ambulatory Unit Record) completed by the Census field representative for each emergency service area and outpatient clinic during induction. For the OPD, imputation procedures were performed for the following variables: item 4 (date of birth), item 5 (sex), item 6 (race), item 7 (ethnicity), item 9 (referral), item 12 (patient seen before), item 16 (disposition), and item 17 (providers). The sorting used was OPD size by clinic type by the 3-digit ICD-9-CM code for principal diagnosis. OPD size was determined from the entry on the NHAMCS-101/U, and clinic type used the following categories: general medicine, surgery, pediatrics, obstetrics/gynecology, and other. ED and OPD records with imputed variables were flagged on the data file. G. MEDICAL CODING The Patient Record forms for the NHAMCS contain several medical items requiring three separate coding systems. The three coding systems are described briefly below. Quality control for the medical coding operation involved a two-way 10-percent independent verification procedure. As an additional control, all Patient Record forms with differences between coders or with illegible entries for the medical coding items (reason for visit, diagnostic and therapeutic procedures, diagnosis, cause of injury, and medication) were reviewed and adjudicated at NCHS. Definitions of the medical items are included in the section entitled, "Patient Record Forms - Instructions and Definitions". 1. Patient's Reason for Visit: Information contained in item 10 of the OPD, and item 11 of the ED Patient Record forms was coded according to an updated version of "A Reason for Visit Classification for Ambulatory Care" (RVC) (reference 10). The system utilizes a modular structure composed of 7 modules. The digits 1 through 7 precede the 3-digit RVC codes to identify the various modules, and digits 8 and 9 are used in special cases, as follows: Prefix Module "1" = symptom module "2" = disease module "3" = diagnostic, screening, and preventive module "4" = treatment module "5" = injuries and adverse effects module "6" = test results module "7" = administrative module "8" = Uncodable entries "9" = special code = blank A maximum of 3 reasons for visit were coded in sequence; coding instructions are contained in the NHAMCS Coding Requirements Manual (reference 11). Copies are available upon request. 2. Physician's Diagnoses: Diagnostic information in item 11 of the OPD and item 12 of the ED Patient Record forms was coded according to the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) (reference 12). The 1994 NHAMCS data codes for diagnoses have the following characteristics: a. The prefix "1" preceding the diagnostic codes has been added to identify all codes in the range 001.00-999.90, e.g. '138100' = '381.00' = Acute nonsuppurative otitis media, unspecified. b. The prefix "20" preceding diagnostic codes represents V code diagnoses V01.0[0]-V82.9[0], e.g. '201081' = 'V10.81' = personal history of malignant neoplasm of bone. NOTE: These prefixes were used because they facilitated data analysis using ACSB software systems. Please note that starting with the 1995 NAMCS public use data files, diagnostic fields will be included that will reflect actual ICD-9-CM codes without prefix or zerofills. c. In addition to the diagnostic codes from the ICD-9-CM there are several unique codes in the diagnostic fields that were developed by NCHS staff: 209900 = - noncodable diagnosis - insufficient information for coding - illegible diagnosis 209910 = - "left before being seen" - "patient walked out" - "not seen by doctor" - "left against medical advice" 209920 = - "transfer to another facility" - "sent to see a specialist" 209970 = diagnosis of "none" 900000 = blank diagnosis A maximum of three diagnoses were coded in sequence. Coding instructions concerning diagnoses are contained in the NHAMCS Coding Requirements Manual (reference 11). 3. Cause of Injury: (ED ONLY) Information contained in item 10 of the Patient Record form (cause of injury) was also coded according to the ICD-9-CM (reference 10), using the Supplemental Classification of External Causes of Injury and Poisoning (E codes). A maximum of three causes of injury were coded, in sequence. Coding instructions are contained in the NHAMCS Coding Requirements Manual, Volume I. In all cases, the "E" prefix has been converted to an "8". 4. Diagnostic and Therapeutic Procedures: Data from part b, item 13 (Tests, surgical and nonsurgical procedures, and therapies) of the OPD Patient Record form were coded according to the ICD-9-CM, using the 4-digit procedure codes in Volume 3. Up to six procedures could be coded for each visit from this item. The procedure classification was also used to code responses to item 15.9 and 16.11 on the ED Patient Record form, with up to three diagnostic services or procedures coded, respectively. Please note that a zero was added to the 4th digit of 3-digit codes. 5. Medication Therapy: The NHAMCS drug data in item 17 on the ED and item 15 on the OPD Patient Record forms have been classified and coded according to a unique classification scheme developed at NCHS (reference 13). The scheme is based on the American Society of Hospital Pharmacists' Drug Product Information File which is maintained by the American Druggist Blue Book Data Center. A list of the drug codes is contained in the section, "Drug Entry Codes and Names." The Patient Record forms allow for the recording of up to 5 drugs per visit. These data files also include the following information for each recorded drug mention: a. Generic name code: A unique, 5-digit code assigned to each official generic name assigned to every drug entity by the United States Pharmacopeia or other responsible authority. b. Prescription status code: A code designed to identify the legal status (prescription or nonprescription) of the drug entry. c. Controlled substance status code: A code used to denote the degree of potential abuse and federal control of a drug entry. d. Composition status code: A code used to distinguish between single- ingredient and combination drugs. Note: If the user is searching for single ingredient (or single entity) drugs, then s/he should utilize the composition status code = '1', in conjunction with the "generic name code" field. A single ingredient drug will have one generic code in the "generic name code" field, and blanks in the five "ingredient codes" fields. Ingredient codes should NOT be used when analyzing single entity drugs. On the other hand, if the user is searching for combination drugs, then s/he should utilize composition status code = '2' in conjunction with the "ingredient codes" fields. A combination drug will have a blank generic code in the "generic name code" field, and from one to five generic codes in the "ingredient codes" fields. The "generic name code" field should NOT be used when analyzing combination drugs. e. Ingredient codes: Codes used to identify the active generic ingredients of combination drugs. A maximum of 5 ingredients can be identified for each combination drug. f. Drug class code: A 4-digit code used to identify the primary class to which the drug entry may belong. These are based on the standard drug classifications used in National Drug Code Directory, 1985 edition (reference 14). The first two digits represent the major drug classes and can be used alone or in conjunction with the additional digits for greater specificity within the major classes. A listing of drug classes is shown in the section, "List of National Drug Code Directory Drug Classes." IMPORTANT: For data users who are interested in analyzing drug data ONLY (apart from visit data), you will need to isolate those records with drugs, or drug mentions, and create a separate datafile of drug mentions. Each Patient Record form can have up to five drug mentions recorded, so whatever subset is created will need to include all of them. This documentation contains marginal data on drug mentions and approximate relative standard errors. Should the data user need additional assistance in analyzing data on drug mentions, the staff of the Ambulatory Care Statistics Branch can be reached by phone at (301) 436-7132. H. ESTIMATION PROCEDURES The probability sample design of the NHAMCS allowed the sample data to be weighted to produce national estimates for the U.S. Unweighted data are not used for analysis as unweighted data ignore the disproportionate sampling used in the NHAMCS. Statistics from the NHAMCS were derived by a multistage estimation procedure that produces essentially unbiased national estimates. Separate national estimates were produced for visits to hospital emergency and outpatient departments. The weight included three basic components: (1) inflation by reciprocals of the probabilities of selection, (2) adjustment for nonresponse, and (3) ratio adjustment to fixed totals. Each component is briefly described below. (1) Inflation by reciprocals of probabilities of selection Because the survey utilized a four-stage sample design, four probabilities of selection existed: (A) the probability of selecting the PSU; (B) the probability of selecting the hospital within the PSU; (C) the probability of selecting the emergency service area or outpatient clinic within the hospital; and (D) the probability of selecting the visit within the particular emergency service area or clinic. The overall probability of including a hospital in the sample was the product of the probability of the PSU being selected multiplied by the probability of the hospital being selected. The probability of selecting the hospital was 1.0 for hospitals in noncertainty PSUs with fewer than five hospitals and was the hospital size divided by a sampling interval for all other hospitals. The sampling intervals for PSUs with more than five hospitals was the cumulative sum of the hospital sizes (the total of ED and OPD visits) in each PSU divided by five. The sampling interval for the certainty PSUs was the cumulative sum of all hospitals in these PSUs divided by 240. The probability of selecting a clinic within a hospital was 1.0 for clinics in hospitals with five or fewer clinics and was the clinic size divided by the sampling interval for clinics in hospitals with more than five clinics. The sampling interval was defined to be the cumulative sum of sizes for the clinics (the expected number of visits during the reporting period) in the hospital divided by five. The probability of selecting a visit was defined as the actual number of visits during the hospital's assigned reporting period divided by the number of Patient Record forms completed. The survey included 13 four-week reporting periods which were inflated to derive annual estimates. (2) Adjustment for nonresponse Estimates from NHAMCS data were adjusted to account for sample units that were in scope, but did not participate in the study. These adjustments were calculated to minimize the impact of nonresponse on final estimates by imputing to nonresponding units the characteristics of similar responding units. As nonresponse may occur at each stage of sampling, several adjustments were required. For these adjustments, hospitals were judged similar if they had the same ownership and were in the same PSU or region and MSA status. Clinics were judged similar if they were of the same clinic type and were in the same PSU. Visits were judged similar if they occurred in the same clinic. (3) Ratio adjustment NHAMCS estimates were adjusted within 12 strata defined by region and ownership. Separate postratio adjustments were made for emergency and outpatient department estimates. For ED estimates, the ratio adjustment for each stratum was a multiplication factor which had as its numerator the number of ED visits in the universe in the stratum and as its denominator the estimated number of ED visits in that stratum. For OPD estimates, the ratio adjustment for each stratum was a multiplication factor which had as its numerator the number of hospitals with an OPD in the universe in the stratum and as its denominator the estimated number of hospitals with OPD's in that stratum. The data for the numerator and denominator of both adjustments were based on figures from the SMG Hospital Market Data Base. I. PATIENT VISIT WEIGHT The "patient visit weight" is a vital component in the process of producing national estimates from sample data and its use should be clearly understood by all data file users. The statistics contained on the data file reflect data concerning only a sample of patient visits, not a complete count of all the visits that occurred in the United States. Each record on the ED file represents one visit in the sample of 26,547 visits, and each record on the OPD file represents one visit in the sample of 29,095 visits. In order to obtain national estimates from the two samples, each record is assigned an inflation factor called the "patient visit weight." By aggregating the "patient visit weights" on the 26,547 ED sample records for 1994 the user can obtain the total of 93,402,004 estimated visits made by all patients to EDs in the United States. Also, by aggregating the "patient visit weights" on the 29,095 OPD sample records for 1994 the user can obtain the total of 66,345,077 estimated visits made by all patients to OPDs in the United States. The marginal tables contain data on numbers of records for selected variables as well as the corresponding national estimates of visits and drug mentions obtained by aggregating the "patient visit weights" on those records. J. HOSPITAL CODE The purpose of this code is to allow for greater analytical depth by permitting the user to link individual Patient Record forms on the data file with individual hospitals. This linking code will enable users to conduct more comprehensive analysis without violating the confidentiality of patients or hospitals. Hospital codes are randomly assigned each year and may be different on the OPD and ED data files. K. CLINIC TYPE CODE (For OPDs only) The purpose of this code is the same as that of the hospital code. It allows the user to identify all records from a particular outpatient clinic. L. POPULATION FIGURES The base population used in computing annual visit rates is presented in Table II. These figures are based on provisional estimates for the civilian noninstitutionalized population as of July 1, 1994, provided by the U.S. Bureau of the Census. The population estimates are presented here solely for the purpose of providing denominators for rate computation and should not be considered official population estimates. Table II. Population figures used in computing annual visit rates with NAMCS data, by age, race, sex, and region: July 1, 1994. ___________________________________________________________________ | | | Age groups |_________________________________________________ Race, sex | | | | | and region | All | < 5 | 5-14 | 15-24 | 25-34 | ages | years | years | years | years ___________________________________________________________________ (in thousands) All races Male | 126,494 | 10,471 | 19,788 | 18,143 | 20,364 Female | 133,139 | 10,009 | 18,872 | 18,027 | 20,990 Total | 259,634 | 20,480 | 38,660 | 36,170 | 41,355 White Male | 105,166 | 8,226 | 15,659 | 14,487 | 16,859 Female | 109,330 | 7,848 | 14,913 | 14,156 | 16,931 Total | 214,496 | 16,074 | 30,573 | 28,643 | 33,790 Black Male | 15,399 | 1,710 | 3,130 | 2,576 | 2,413 Female | 17,636 | 1,666 | 3,052 | 2,831 | 2,963 Total | 33,035 | 3,376 | 6,182 | 5,407 | 5,376 Other Male | 5,930 | 535 | 999 | 1,080 | 1,093 Female | 6,173 | 495 | 907 | 1,040 | 1,096 Total | 12,103 | 1,030 | 1,906 | 2,120 | 2,189 __________________________ Region Northeast | 50,610 Midwest | 63,238 South | 88,088 West | 57,697 ____________________________________________________________________ | | Age groups |__________________________________________________ Race, sex, | and region | 35-44 | 45-54 | 55-64 | 65-74 | 75 years | years | years | years | years | and over ____________________________________________________________________ (in thousands) All races Male | 20,452 | 14,505 | 9,839 | 8,112 | 4,820 Female | 21,086 | 15,213 | 10,848 | 10,142 | 7,952 Total | 41,538 | 29,718 | 20,687 | 18,253 | 12,772 White Male | 17,207 | 12,456 | 8,628 | 7,265 | 4,378 Female | 17,278 | 12,789 | 9,309 | 8,919 | 7,187 Total | 34,485 | 25,245 | 17,937 | 16,184 | 11,565 Black Male | 2,303 | 1,392 | 889 | 644 | 341 Female | 2,738 | 1,692 | 1,156 | 909 | 630 Total | 5,041 | 3,084 | 2,045 | 1,553 | 971 Other Male | 942 | 656 | 322 | 203 | 101 Female | 1,070 | 733 | 383 | 314 | 135 Total | 2,012 | 1,389 | 705 | 516 | 236 ____________________________________________________________________ NOTES: Based on U.S. Bureau of the Census estimates of the civilian noninstitutionalized population of the United States as of July 1, 1994. Figures may not add to totals because of rounding. REFERENCES 1. Current Estimates from the National Health Interview Survey. 1991. National Center for Health Statistics. Vital Health Stat 10(184). 1992. 2. Tenney JB, White KL, Williamson JW. National Ambulatory Medical Care Survey: Background and Methodology. National Center for Health Statistics. Vital Health Stat 2(61). 1974. 3. Loft JD, Sheatsley PB, Frankel MR. Comparison Report on the Hospital Ambulatory Medical Care Evaluation Study. Contract No. 282-82-2111. Chicago, Illinois: National Opinion Research Center, 1985. 4. McCaig LF, McLemore T. Plan and Operation of the National Hospital Ambulatory Medical Care Survey. National Center for Health Statistics. Vital and Health Stat 1(34). 1994. 5. Lipkind KL, National Hospital Ambulatory Medical Care Survey: 1994 Outpatient Department Summary. Advance data from vital and health statistics; no. 276. Hyattsville, Maryland: National Center for Heath Statistics. 1995. 6. Stussman, BJ, National Hospital Ambulatory Medical Care Survey: 1994 Emergency Department Summary. Advance data from vital and health statistics; no. 275. Hyattsville, Maryland: National Center for Health Statistics. 1995. 7. Massey JT, Moore TF, Parsons VL, Tadros W. Design and estimation for the National Health Interview Survey, 1985-94. National Center for Health Statistics. Vital Health Stat 2(110). 1989. 8. Methodological Report on the Hospital Ambulatory Medical Care Evaluation Study. Contract No. 282-82-2111. Chicago, Illinois. National Opinion Research Center. 1984. 9. Final Report - Survey of Hospital Emergency and Outpatient Departments. Contract No. 200-88-7017. Rockville, Maryland. Westat. 1990. 10. Schneider D, Appleton L, McLemore T. A Reason for Visit Classification for Ambulatory Care. National Center for Health Statistics. Vital Health Stat 2(78). 1979. 11. National Hospital Ambulatory Medical Care Survey: Coding Requirements, Volume 1, 1996. 12. Public Health Service and Health Care Financing Administration. International Classification of Diseases, 9th Revision, Clinical Modification. Washington: Public Health Service. 1980. 13. Koch H, Campbell W. The Collection and Processing of Drug Information. National Ambulatory Medical Care Survey, 1980. National Center for Health Statistics. Vital and Health Stat 2 (90). 1982. 14. Food and Drug Administration. National Drug Code Directory, 1985 Edition. Washington: Public Health Service. 1985. Information concerning additional reports using NHAMCS data that have been published or are scheduled for publication through NCHS may be obtained from the Ambulatory Care Statistics Branch. FORMAT OF EMERGENCY DEPARTMENT MICRO-DATA FILE This section contains a detailed breakdown of the data records on the Emergency Department micro-data file. The data are arranged sequentially according to their physical location on the file. Unless otherwise stated in the "item description" column, the data are derived from the Emergency Department (ED) Patient Record form. The hospital induction questionnaire and the SMG Hospital Market Data Base are other sources of data, while the computer generates other items by recoding selected data items. Item Field File No. Length Location Item Description and Codes 1 6 1-6 Date of visit 1.1 2 1-2 Month of visit 01-12: January-December 1.2 2 3-4 Day of visit 01-31 1.3 2 5-6 Year of visit Last 2 digits of year (93 or 94)* 2 2 7-8 Patient age (in years; derived from date of birth) 00-99 3 1 9 Sex 1 = Female 2 = Male 4 1 10 Race 1 = White 2 = Black 3 = Asian/Pacific Islander 4 = American Indian/Eskimo/Aleut 5 1 11 Ethnicity 1 = Hispanic origin 2 = Not Hispanic * The 1994 NHAMCS included data collected from Dec. 27, 1993 to Dec. 25, 1994. Item Field File No. Length Location Item Description and Codes 6 9 12-20 Expected source(s) of payment 6.1 1 12 Private/commercial (1=Yes, 0=No) 6.2 1 13 Medicare " 6.3 1 14 Medicaid " 6.4 1 15 Other government " 6.5 1 16 HMO/other prepaid " 6.6 1 17 Patient paid " 6.7 1 18 No charge " 6.8 1 19 Other " 6.9 1 20 Unspecified " 7 1 21 Place of injury 1 = Home 2 = Work 3 = School/Day Care 4 = Street/Highway 5 = Other 6 = Injury indicated, place unspecified 9 = Blank or invalid 8 15 22-36 Cause of injury (See Description of NHAMCS.) 8.1 5 22-26 Cause # 1: 88000-89999 = E800.0-E999.9 80000 = Blank 80010 = Illegible 80019 = Injury indicated, cause unspecified 8.2 5 27-31 Cause # 2: 88000-89999 = E800.0-E999.9 80000 = Blank 80010 = Illegible 80019 = Injury indicated, cause unspecified 8.3 5 32-36 Cause # 3: 88000-89999 = E800.0-E999.9 80000 = Blank 80010 = Illegible 80019 = Injury indicated, cause unspecified 9 15 37-51 Patient's reason(s) for visit (See Description of NHAMCS.) 9.1 5 37-41 Reason # 1: 10050-89990 = 1005.0-8999.0 90000 = Blank 9.2 5 42-46 Reason # 2: 10050-89990 = 1005.0-8999.0 90000 = Blank 9.3 5 47-51 Reason # 3: 10050-89990 = 1005.0-8999.0 90000 = Blank 10 18 52-69 Physician's diagnoses (See Description of the NHAMCS.) 10.1 6 52-57 Diagnosis # 1: 100100-208290 = 001.0[0]-V82.9[0] 209900 = Noncodable, insufficient info for coding, illegible 209970 = Diagnosis of "none" 900000 = Blank 10.2 6 58-63 Diagnosis # 2: 100100-208290 = 001.0[0]-V82.9[0] 209900 = Noncodable, insufficient info for coding, illegible 209970 = Diagnosis of "none" 900000 = Blank 10.3 6 64-69 Diagnosis # 3: 100100-208290 = 001.0[0]-V82.9[0] 209900 = Noncodable, insufficient info for coding, illegible 209970 = Diagnosis of "none" 900000 = Blank 11 1 70 Urgency of this visit 1 = Urgent/Emergent 2 = Non-urgent 12 1 71 Is problem alcohol- or drug related? 1 = Neither 2 = Alcohol-related 3 = Drug-related 4 = Both 5 = Unknown 13 1 72 Were medications ordered or provided at this visit? 1 = Yes 2 = No 14 1 73 Number of medications coded 0-5 15 25 74-98 Medications (See Description of the NHAMCS.) 15.1 5 74-78 Medication Code # 1 00005-94197 = 00005-94197 90000 = Blank 99980 = Unknown entry, other 99999 = Illegible entry Item Field File No. Length Location Item Description and Codes 15.2 5 79-83 Medication code # 2 00005-94197 = 00005-94197 90000 = Blank 99980 = Unknown entry, other 99999 = Illegible entry 15.3 5 84-88 Medication code # 3 00005-94197 = 00005-94197 90000 = Blank 99980 = Unknown entry, other 99999 = Illegible entry 15.4 5 89-93 Medication code # 4 00005-94197 = 00005-94197 90000 = Blank 99980 = Unknown entry, other 99999 = Illegible entry 15.5 5 94-98 Medication code # 5 00005-94197 = 00005-94197 90000 = Blank 99980 = Unknown entry, other 99999 = Illegible entry 16 20 99-118 Diagnostic/screening services 16.1 1 99 None (1=Yes, 0=No) 16.2 1 100 Blood pressure check " 16.3 1 101 Urinalysis " 16.4 1 102 HIV Serology " 16.5 1 103 EKG " 16.6 1 104 Chest x ray " 16.7 1 105 Extremity x ray " 16.8 1 106 Other diagnostic imaging " Other diagnostic/screening services 16.9 4 107-110 Other (specify) #1 (ICD-9-CM, Vol. 3, Procedures) 0101-9998 = 01.01-99.98 0000 = Blank 9999 = Other and uncodable 16.10 4 111-114 Other (specify) #2 (ICD-9-CM, Vol. 3, Procedures) 0101-9998 = 01.01-99.98 0000 = Blank 9999 = Other and uncodable 16.11 4 115-118 Other (specify) #3 (ICD-9-CM, Vol. 3, Procedures) 0101-9998 = 01.01-99.98 0000 = Blank 9999 = Other and uncodable NA 3 119-121 Blank 17 22 122-143 Procedures 17.1 1 122 None (1=Yes, 0=No) 17.2 1 123 Endotracheal intubation " 17.3 1 124 CPR " 17.4 1 125 IV fluids " 17.5 1 126 NG tube/gastric lavage " 17.6 1 127 Wound care " 17.7 1 128 Eye/ENT care " 17.8 1 129 Orthopedic care " 17.9 1 130 Bladder catheter " 17.10 1 131 Lumbar puncture " Other procedures 17.11 4 132-135 Other (specify) #1 (ICD-9-CM, Vol. 3, Procedures) 0101-9998 = 01.01-99.98 0000 = Blank 9999 = Other and uncodable 17.12 4 136-139 Other (specify) #2 (ICD-9-CM, Vol. 3, Procedures) 0101-9998 = 01.01-99.98 0000 = Blank 9999 = Other and uncodable 17.13 4 140-143 Other (specify) #3 (ICD-9-CM, Vol. 3, Procedures) 0101-9998 = 01.01-99.98 0000 = Blank 9999 = Other and uncodable 18 9 144-152 Disposition of this visit 18.1 1 144 No follow-up planned (1=Yes, 0=No) 18.2 1 145 Return to ED P.R.N. " 18.3 1 146 Return to ED- appointment " 18.4 1 147 Refer to referring physician " 18.5 1 148 Refer to other physician/clinic " 18.6 1 149 Admit to hospital " 18.7 1 150 Transfer to other facility " 18.8 1 151 DOA/died in ED " 18.9 1 152 Other " 19 8 153-160 Providers seen this visit 19.1 1 153 Resident/Intern (1=Yes, 0=No) 19.2 1 154 Staff physician " 19.3 1 155 Other physician " 19.4 1 156 Physician assistant/Nurse practitioner " 19.5 1 157 Registered nurse " 19.6 1 158 Licensed practical nurse " 19.7 1 159 Nurse's aid " 19.8 1 160 Other " 20 5 161-165 Patient visit weight (See Description of the NHAMCS, page 16.) A right-justified, alphanumeric integer developed by the NHAMCS staff for the purpose of producing national estimates from sample data. 21 1 166 Geographic region (Based on location of facility.) 1 = Northeast 2 = Midwest 3 = South 4 = West 22 1 167 Metropolitan/nonmetropolitan location (Based on location of facility, in conjunction with the definition of the Bureau of the Census and the U.S. Office of Management and Budget.) 1 = MSA (Metropolitan Statistical Area) 2 = Non-MSA 23 1 168 Hospital ownership 1 = Voluntary non-profit 2 = Government, not Federal 3 = Proprietary 24 3 169-171 Hospital code 001-605 = A unique code assigned to all the records from a particular hospital. Item Field File No. Length Location Item Description and Codes ******THE FOLLOWING FIELDS WERE FLAGGED IF DATA WERE IMPUTED TO REPLACE BLANKS FOR THE ITEMS LISTED BELOW ******** 25 8 172-179 Imputations 25.1 1 172 Birth year (1=data imputed, blank=not imputed) 25.2 1 173 Sex " 25.3 1 174 Race " 25.4 1 175 Ethnicity " 25.5 1 176 Urgency " 25.6 1 177 Alcohol- or drug-related " 25.7 1 178 Disposition of visit " 25.8 1 179 Providers seen " END OF IMPUTED DATA FLAGS ****************************************************************************** Item Field File No. Length Location Item Description and Codes 26-31 37 180-216 Drug-related information for MEDCODE #1 26 5 180-184 Generic name code (See Generic Code List.) 50001-92503 = Specific generic code 50000 = Generic name undetermined 27 1 185 Prescription status code 1 = Prescription drug 2 = Nonprescription drug 3 = Undetermined 28 1 186 Controlled substance status code 1 = Schedule I (research only) 2 = Schedule II 3 = Schedule III 4 = Schedule IV 5 = Schedule V 6 = No control 7 = Undetermined 29 1 187 Composition status code 1 = Single entity drug 2 = Combination drug 3 = Undetermined 30 4 188-191 Drug classes (Adapted from the National Drug Code Directory [NDC]). See NDC Code List.) 0100-1945 = NDC drug class 2000-2097 = Unclassified/miscellaneous Blank = Unknown 31 25 192-216 Ingredient codes (Ingredients of combination drugs; maximum of 5 generic name codes) 31.1 5 192-196 Ingredient code (50001-92503, or 50000) 31.2 5 197-201 Ingredient code (50001-92503, or 50000) 31.3 5 202-206 Ingredient code (50001-92503, or 50000) 31.4 5 207-211 Ingredient code (50001-92503, or 50000) 31.5 5 212-216 Ingredient code (50001-92503, or 50000) 32-37 37 217-253 Drug-related information for MEDCODE #2 32 5 217-221 Generic name code (See Generic Code List.) 50001-92503 = Specific generic code 50000 = Generic name undetermined 33 1 222 Prescription status code 1 = Prescription drug 2 = Nonprescription drug 3 = Undetermined 34 1 223 Controlled substance status code 1 = Schedule I (research only) 2 = Schedule II 3 = Schedule III 4 = Schedule IV 5 = Schedule V 6 = No control 7 = Undetermined 35 1 224 Composition status code 1 = Single entity drug 2 = Combination drug 3 = Undetermined 36 4 225-228 Drug Classes (Adapted from the National Drug Code Directory [NDC]. See NDC Code List.) 0100-1945 = NDC drug class 2000-2097 = Unclassified/miscellaneous Blank = Unknown 37 25 229-253 Ingredient codes (Ingredients of combination drugs; maximum of 5 generic name codes) 37.1 5 229-233 Ingredient code (50001-92503, or 50000) 37.2 5 234-238 Ingredient code (50001-92503, or 50000) 37.3 5 239-243 Ingredient code (50001-92503, or 50000) 37.4 5 244-248 Ingredient code (50001-92503, or 50000) 37.5 5 249-253 Ingredient code (50001-92503, or 50000) 38-43 37 254-290 Drug-related information for MEDCODE #3 38 5 254-258 Generic name code (See Generic Code List.) 50001-92503 = Specific generic code 50000 = Generic name undetermined 39 1 259 Prescription status code 1 = Prescription drug 2 = Nonprescription drug 3 = Undetermined 40 1 260 Controlled substance status code 1 = Schedule I (research only) 2 = Schedule II 3 = Schedule III 4 = Schedule IV 5 = Schedule V 6 = No control 7 = Undetermined 41 1 261 Composition status code 1 = Single entity drug 2 = Combination drug 3 = Undetermined 42 4 262-265 Drug classes (Adapted from the National Drug Code Directory [NDC]. See NDC Code List.) 0100-1945 = NDC drug class 2000-2097 = Unclassified/miscellaneous Blank = Unknown 43 25 266-290 Ingredient codes (Ingredients of combination drugs; maximum of 5 generic name codes) 43.1 5 266-270 Ingredient code (50001-92503, or 50000) 43.2 5 271-275 Ingredient code (50001-92503, or 50000) 43.3 5 276-280 Ingredient code (50001-92503, or 50000) 43.4 5 281-285 Ingredient code (50001-92503, or 50000) 43.5 5 286-290 Ingredient code (50001-92503, or 50000) 44-49 37 291-327 Drug-related information for MEDCODE #4 44 5 291-295 Generic name code (See Generic Code List.) 50001-92503 = Specific generic code 50000 = Generic name undetermined 45 1 296 Prescription status code 1 = Prescription drug 2 = Nonprescription drug 3 = Undetermined 46 1 297 Controlled substance status code 1 = Schedule I (research only) 2 = Schedule II 3 = Schedule III 4 = Schedule IV 5 = Schedule V 6 = No control 7 = Undetermined 47 1 298 Composition status code 1 = Single entity drug 2 = Combination drug 3 = Undetermined 48 4 299-302 Drug Classes (Adapted from the National Drug Code Directory [NDC]. See NDC Code List.) 0100-1945 = NDC drug class 2000-2097 = Unclassified/miscellaneous Blank = Unknown 49 25 303-327 Ingredient codes (Ingredients of combination drugs; maximum of 5 generic name codes) 49.1 5 303-307 Ingredient code (50001-92503, or 50000) 49.2 5 308-312 Ingredient code (50001-92503, or 50000) 49.3 5 313-317 Ingredient code (50001-92503, or 50000) 49.4 5 318-322 Ingredient code (50001-92503, or 50000) 49.5 5 323-327 Ingredient code (50001-92503, or 50000) Item Field File No. Length Location Item Description and Codes 50-55 37 328-364 Drug-related information for MEDCODE #5 50 5 328-332 Generic name code (See Generic Code List.) 50001-92503 = Specific generic code 50000 = Generic name undetermined 51 1 333 Prescription status code 1 = Prescription drug 2 = Nonprescription drug 3 = Undetermined 52 1 334 Controlled substance status code 1 = Schedule I (research only) 2 = Schedule II 3 = Schedule III 4 = Schedule IV 5 = Schedule V 6 = No control 7 = Undetermined 53 1 335 Composition status code 1 = Single entity drug 2 = Combination drug 3 = Undetermined 54 4 336-339 Drug Classes (Adapted from the National Drug Code Directory [NDC]. See NDC Code List.) 0100-1945 = NDC drug class 2000-2097 = Unclassified/miscellaneous Blank = Unknown 55 25 340-364 Ingredient codes (Ingredients of combination drugs; maximum of 5 generic name codes) 55.1 5 340-344 Ingredient code (50001-92503, or 50000) 55.2 5 345-349 Ingredient code (50001-92503, or 50000) 55.3 5 350-354 Ingredient code (50001-92503, or 50000) 55.4 5 355-359 Ingredient code (50001-92503, or 50000) 55.5 5 360-364 Ingredient code (50001-92503, or 50000) ****END OF DRUG INFORMATION****** 56 1 365 Race Recode 1 = White, 2 = Black, 3 = Other FORMAT OF OUTPATIENT DEPARTMENT MICRO-DATA FILE This section contains a detailed breakdown of the data file records on the Outpatient Department micro-data file. The data are arrranged sequentially according to their physical location on the file. Unless otherwise stated in the "item description" column, the data are derived from the Outpatient Department (OPD) Patient Record form. The hospital induction questionnaire and the SMG Hospital Market Data Base are alternate sources of data, while the computer generates other items by recoding selected data items. Item Field File No. Length Location Item Description and Codes 1 6 1-6 Date of visit 1.1 2 1-2 Month of visit 01-12: January-December 1.2 2 3-4 Day of visit 01-31 1.3 2 5-6 Year of visit Last 2 digits of year (93 or 94)* 2 2 7-8 Patient age (in years; derived from date of birth) 00-99 3 1 9 Sex 1 = Female 2 = Male 4 1 10 Race 1 = White 2 = Black 3 = Asian/Pacific Islander 4 = American Indian/Eskimo/Aleut 5 1 11 Ethnicity 1 = Hispanic origin 2 = Not Hispanic * The 1994 NHAMCS included data collected from Dec. 27, 1993 to Dec. 25, 1994. 6 9 12-20 Expected source(s) of payment 6.1 1 12 Private/commercial (1=Yes, 0=No) 6.2 1 13 Medicare " 6.3 1 14 Medicaid " 6.4 1 15 Other government " 6.5 1 16 HMO/other prepaid " 6.6 1 17 Patient paid " 6.7 1 18 No charge " 6.8 1 19 Other " 6.9 1 20 Unspecified " 7 1 21 Was patient referred by another physician? 1 = Yes 2 = No 8 15 22-36 Patient's reason(s) for visit (See Description of the NHAMCS.) 8.1 5 22-26 Reason # 1: 10050-89990 = 1005.0-8999.0 90000 = Blank 8.2 5 27-31 Reason # 2: 10050-89990 = 1005.0-8999.0 90000 = Blank 8.3 5 32-36 Reason # 3: 10050-89990 = 1005.0-8999.0 90000 = Blank 9 18 37-54 Physician's diagnoses (See Description of the NHAMCS.) 9.1 6 37-42 Diagnosis # 1: 100100-208290 = 001.0[0]-V82.9[0] 209900 = Noncodable, insufficient info for coding, illegible 209970 = Diagnosis of "none" 900000 = Blank 9.2 6 43-48 Diagnosis # 2: 100100-208290 = 001.0[0]-V82.9[0] 209900 = Noncodable, insufficient info for coding, illegible 209970 = Diagnosis of "none" 900000 = Blank 9.3 6 49-54 Diagnosis # 3: 100100-208290 = 001.0[0]-V82.9[0] 209900 = Noncodable, insufficient info for coding, illegible 209970 = Diagnosis of "none" 900000 = Blank Item Field File No. Length Location Item Description and Codes 10.1 1 55 Have you seen patient before? 1 = Yes 2 = No 10.2 1 56 If yes, for the condition in item 11a? 0 = Not applicable 1 = Yes 2 = No 11 37 57-93 Tests, surgical and nonsurgical procedures, and therapies 11.1 1 57 None (1=Yes, 0=No) A. Selected services 11.2 1 58 Blood pressure " 11.3 1 59 Urinalysis " 11.4 1 60 Spirometry " 11.5 1 61 Allergy testing " 11.6 1 62 HIV serology " 11.7 1 63 Other blood test " B. All other services (ICD-9-CM, Vol. 3) 11.8 4 64-67 Service #1 Procedure code 0101-9998 = 01.01-99.98 0000 = Blank 9999 = Other and uncodable 11.9 1 68 Service #1 Performed/Ordered 1 = Performed 2 = Ordered 3 = Unknown 11.10 4 69-72 Service #2 0101-9998 = 01.01-99.98 0000 = Blank 9999 = Other and uncodable 11.11 1 73 Service #2 Performed/Ordered 1 = Performed 2 = Ordered 3 = Unknown 11.12 4 74-77 Service #3 0101-9998 = 01.01-99.98 0000 = Blank 9999 = Other and uncodable 11.13 1 78 Service #3 Performed/Ordered 1 = Performed 2 = Ordered 3 = Unknown 11.14 4 79-82 Service #4 0101-9998 = 01.01-99.98 0000 = Blank 9999 = Other and uncodable 11.15 1 83 Service #4 Performed/Ordered 1 = Performed 2 = Ordered 3 = Unknown 11.16 4 84-87 Service #5 0101-9998 = 01.01-99.98 0000 = Blank 9999 = Other and uncodable 11.17 1 88 Service #5 Performed/Ordered 1 = Performed 2 = Ordered 3 = Unknown 11.18 4 89-92 Service #6 0101-9998 = 01.01-99.98 0000 = Blank 9999 = Other and uncodable 11.19 1 93 Service #6 Performed/Ordered 1 = Performed 2 = Ordered 3 = Unknown 12 10 94-103 Counseling/Education 12.1 1 94 None (1=Yes, 0=No) 12.2 1 95 Exercise " 12.3 1 96 Cholesterol reduction " 12.4 1 97 Weight reduction " 12.5 1 98 Smoking cessation " 12.6 1 99 Growth/development " 12.7 1 100 Injury prevention " 12.8 1 101 HIV transmission " 12.9 1 102 Other STD transmission " 12.10 1 103 Other " 13 25 104-128 Medications (See Description of the NHAMCS.) 13.1 5 104-108 Medication # 1 00005-94197 = 00005-94197 90000 = Blank 99980 = Unknown entry, Other 99999 = Illegible entry 13.2 5 109-113 Medication code # 2 00005-94197 = 00005-94197 90000 = Blank 99980 = Unknown entry, Other 99999 = Illegible entry 13.3 5 114-118 Medication code # 3 00005-94197 = 00005-94197 90000 = Blank 99980 = Unknown entry, Other 99999 = Illegible entry 13.4 5 119-123 Medication code # 4 00005-94197 = 00005-94197 90000 = Blank 99980 = Unknown entry, Other 99999 = Illegible entry 13.5 5 124-128 Medication code # 5 00005-94197 = 00005-94197 90000 = Blank 99980 = Unknown entry, Other 99999 = Illegible entry 14 1 129 Were medications ordered or provided at this visit? 1 = Yes 2 = No 15 1 130 Number of medications coded 0-5 16 8 131-138 Disposition of this visit 16.1 1 131 No follow-up planned (1=Yes, 0=No) 16.2 1 132 Return to Clinic P.R.N. " 16.3 1 133 Return to Clinic-appointment " 16.4 1 134 Telephone follow-up planned " 16.5 1 135 Return to referring physician " 16.6 1 136 Refer to other physician/clinic " 16.7 1 137 Admit to hospital " 16.8 1 138 Other " 17 8 139-146 Providers seen this visit 17.1 1 139 Resident/Intern (1=Yes, 0=No) 17.2 1 140 Staff physician " 17.3 1 141 Other physician " 17.4 1 142 Physician assistant/Nurse practitioner " 17.5 1 143 Registered nurse " 17.6 1 144 Licensed practical nurse " 17.7 1 145 Nurse's aid " 17.8 1 146 Other " 18 5 147-151 Patient visit weight (See Description of the NHAMCS, page 16.) A right justified, alphanumeric integer developed by the ACSB staff for the purpose of producing national estimates from sample data. 19 1 152 Geographic region Based on facility location. 1 = Northeast 2 = Midwest 3 = South 4 = West 20 1 153 Metropolitan/nonmetropolitan Based on facility location, in conjunction with the definition of the Bureau of the Census and the U.S. Office of Management and Budget. 1 = MSA (Metropolitan Statistical Area) 2 = Non-MSA 21 1 154 Hospital ownership 1 = Voluntary non-profit 2 = Government, non-Federal 3 = Proprietary 22 3 155-157 Hospital code 001-605 = A unique code assigned to all of the records from a particular hospital 23 1 158 Clinic type 1 = General medicine 2 = Surgery 3 = Pediatrics 4 = Obstetrics/Gynecology 5 = Other 6 = Substance abuse Item Field File No. Length Location Item Description and Codes ******THE FOLLOWING FIELDS WERE FLAGGED IF DATA WERE IMPUTED TO REPLACE BLANKS IN ANY OF THE ITEMS LISTED BELOW ************ 24 10 159-168 Imputations 24.1 1 159 Birth year (1 = data imputed blank = not imputed) 24.2 1 160 Sex " 24.3 1 161 Referral " 24.4 1 162 Seen patient before " 24.5 1 163 If yes, for diagnosis in 11a " 24.6 1 164 Disposition " 24.7 1 165 Providers seen " 24.8 1 166 Race " 24.9 1 167 Ethnicity " 24.10 1 168 Visit date " END OF IMPUTED DATA FLAGS ***************************************************************************** 25-30 37 169-205 Drug related information for MEDCODE #1 25 5 169-173 Generic name code (See Generic Code List.) 50005-92503 = Specific generic code 50000 = Generic name undetermined 26 1 174 Prescription status code 1 = Prescription drug 2 = Nonprescription drug 3 = Undetermined 27 1 175 Controlled substance status code 1 = Schedule I (research only) 2 = Schedule II 3 = Schedule III 4 = Schedule IV 5 = Schedule V 6 = No control 7 = Undetermined 28 1 176 Composition status code 1 = Single entity drug 2 = Combination drug 3 = Undetermined 29 4 177-180 Drug classes (Adapted from the National Drug Code Directory [NDC]. See NDC Code List. 0100-1945 = NDC drug class 2000-2097 = Unclassified/miscellaneous Blank = Unknown 30 25 181-205 Ingredient codes (Ingredients of combination drugs; maximum of 5 generic name codes) 30.1 5 181-185 Ingredient code (50005-92503, or 50000) 30.2 5 186-190 Ingredient code (50005-92503, or 50000) 30.3 5 191-195 Ingredient code (50005-92503, or 50000) 30.4 5 196-200 Ingredient code (50005-92503, or 50000) 30.5 5 201-205 Ingredient code (50005-92503, or 50000) 31-36 37 206-242 Drug related information for MEDCODE #2 31 5 206-210 Generic name code (See Generic Code List.) 50005-92503 = Specific generic code 50000 = Generic name undetermined 32 1 211 Prescription status code 1 = Prescription drug 2 = Nonprescription drug 3 = Undetermined 33 1 212 Controlled substance status code 1 = Schedule I (research only) 2 = Schedule II 3 = Schedule III 4 = Schedule IV 5 = Schedule V 6 = No control 7 = Undetermined 34 1 213 Composition status code 1 = Single entity drug 2 = Combination drug 3 = Undetermined 35 4 214-217 Drug classes (Adapted from the National Drug Code Directory [NDC]. See NDC Code List.) 0100-1945 = NDC drug class 2000-2097 = Unclassified/miscellaneous Blank = Unknown 36 25 218-242 Ingredient codes (Ingredients of combination drugs; maximum of 5 generic name codes) 36.1 5 218-222 Ingredient code (50005-92503, or 50000) 36.2 5 223-227 Ingredient code (50005-92503, or 50000) 36.3 5 228-232 Ingredient code (50005-92503, or 50000) 36.4 5 233-237 Ingredient code (50005-92503, or 50000) 36.5 5 238-242 Ingredient code (50005-92503, or 50000) Item Field File No. Length Location Item Description and Codes 37-42 37 243-279 Drug related information for MEDCODE #3 37 5 243-247 Generic name code (See Generic Code List.) 50005-92503 = Specific generic code 50000 = Generic name undetermined 38 1 248 Prescription status code 1 = Prescription drug 2 = Nonprescription drug 3 = Undetermined 39 1 249 Controlled substance status code 1 = Schedule I (research only) 2 = Schedule II 3 = Schedule III 4 = Schedule IV 5 = Schedule V 6 = No control 7 = Undetermined 40 1 250 Composition status code 1 = Single entity drug 2 = Combination drug 3 = Undetermined 41 4 251-254 Drug classes (adapted from the National Drug Code Directory [NDC]. See NDC Code List.) 0100-1945 = NDC drug class 2000-2097 = Unclassified/miscellaneous Blank = Unknown 42 25 255-279 Ingredient codes (Ingredients of combination drugs; maximum of 5 generic name codes) 42.1 5 255-259 Ingredient code (50005-92503, or 50000) 42.2 5 260-264 Ingredient code (50005-92503, or 50000) 42.3 5 265-269 Ingredient code (50005-92503, or 50000) 42.4 5 270-274 Ingredient code (50005-92503, or 50000) 42.5 5 275-279 Ingredient code (50005-92503, or 50000) 43-48 37 280-316 Drug related information for MEDCODE #4 43 5 280-284 Generic name code (See Generic Code List.) 50005-92503 = Specific generic code 50000 = Generic name undetermined 44 1 285 Prescription status code 1 = Prescription drug 2 = Nonprescription drug 3 = Undetermined 45 1 286 Controlled substance status code 1 = Schedule I (research only) 2 = Schedule II 3 = Schedule III 4 = Schedule IV 5 = Schedule V 6 = No control 7 = Undetermined 46 1 287 Composition status code 1 = Single entity drug 2 = Combination drug 3 = Undetermined 47 4 288-291 Drug classes (Adapted from the National Drug Code Directory [NDC]. See NDC Code List.) 0100-1945 = NDC drug class 2000-2097 = Unclassified/miscellaneous Blank = Unknown 48 25 292-316 Ingredient codes (Ingredients of combination drugs; maximum of 5 generic name codes) 48.1 5 292-296 Ingredient code (50005-92503, or 50000) 48.2 5 297-301 Ingredient code (50005-92503, or 50000) 48.3 5 302-306 Ingredient code (50005-92503, or 50000) 48.4 5 307-311 Ingredient code (50005-92503, or 50000) 48.5 5 312-316 Ingredient code (50005-92503, or 50000) 49-54 37 317-353 Drug related information for MEDCODE #5 49 5 317-321 Generic name code (See Generic Code List.) 50005-92503 = Specific generic code 50000 = Generic name undetermined 50 1 322 Prescription status code 1 = Prescription drug 2 = Nonprescription drug 3 = Undetermined 51 1 323 Controlled substance status code 1 = Schedule I (research only) 2 = Schedule II 3 = Schedule III 4 = Schedule IV 5 = Schedule V 6 = No control 7 = Undetermined 52 1 324 Composition status code 1 = Single entity drug 2 = Combination drug 3 = Undetermined 53 4 325-328 Drug classes (Adapted from the National Drug Code Directory [NDC]. See NDC Code List.) 0100-1945 = NDC drug class 2000-2097 = Unclassified/miscellaneous Blank = Unknown 54 25 329-353 Ingredient codes (Ingredients of combination drugs; maximum of 5 generic name codes) 54.1 5 329-333 Ingredient code (50005-92503, or 50000) 54.2 5 334-338 Ingredient code (50005-92503, or 50000) 54.3 5 339-343 Ingredient code (50005-92503, or 50000) 54.4 5 344-348 Ingredient code (50005-92503, or 50000) 54.5 5 349-353 Ingredient code (50005-92503, or 50000) ***** END OF DRUG INFORMATION ****** 55 1 354 Race Recode 1 = White, 2 = Black, 3 = Other MARGINAL DATA A. EMERGENCY DEPARTMENT PATIENT VISITS PATIENT AGE TOTAL < 15 15-24 25-44 45-64 65-74 75+ ALL 26547 6438 4439 8200 3783 1633 2054 REC 93402004 23750673 15411106 28219177 13010635 5796701 7213712 VIS 100.000 25.428 16.500 30.213 13.930 6.206 7.723 PER ----------------------------------------------------------------------------- PATIENT SEX TOTAL FEMALE MALE ALL 26547 13737 12810 RECORDS 93402004 48735790 44666214 VISITS 100.000 52.179 47.821 PERCENT ----------------------------------------------------------------------------- PATIENT RACE ASIAN/ AMERICAN PACIFIC INDIAN/ TOTAL WHITE BLACK ISLANDER ESKIMO/ALEUT ALL 26547 19923 5761 725 138 RECORDS 93402004 72337064 18603425 1489262 972253 VISITS 100.000 77.447 19.918 1.594 1.041 PERCENT ----------------------------------------------------------------------------- ETHNICITY NOT TOTAL HISPANIC HISPANIC ALL 26547 3389 23158 RECORDS 93402004 10759581 82642423 VISITS 100.000 11.520 88.480 PERCENT ----------------------------------------------------------------------------- A. EMERGENCY DEPARTMENT PATIENT VISITS (cont.) EXPECTED SOURCES OF PAYMENT PRIVATE/ OTHER TOTAL COMMERCIAL MEDICARE MEDICAID GOV'T ALL 26547 8612 3949 6427 920 93402004 32374899 13933441 23053829 3097854 100.000 34.662 14.918 24.682 3.317 HMO/OTHER PATIENT NO PREPAID PAID CHARGE OTHER UNSPECIFIED 2910 3970 67 1751 568 RECORDS 8466579 12522712 226530 6093115 2315487 VISITS 9.065 13.407 0.243 6.524 2.479 PERCENT ----------------------------------------------------------------------------- PLACE OF INJURY SCHOOL/ STREET/ OTHER TOTAL HOME WORK DAY CARE HIGHWAY PLACE ALL 26547 4281 1389 393 1590 892 93402004 15468658 5146280 1576836 5407780 3197382 100.000 16.561 5.510 1.688 5.790 3.423 UNSPECIFIED BLANK OR LOCATION INVALID 2629 15373 RECORDS 8842958 53762110 VISITS 9.468 57.560 PERCENT ---------------------------------------------------------------------------- URGENCY OF URGENT/ NON- THIS VISIT TOTAL EMERGENT URGENT ALL 26547 12727 13820 RECORDS 93402004 44091130 49310874 VISITS 100.000 47.206 52.794 PERCENT ---------------------------------------------------------------------------- IS PROBLEM ALCOHOL OR DRUG RELATED? ALCOHOL DRUG TOTAL RELATED RELATED NEITHER BOTH UNKNOWN ALL 26547 22096 670 417 101 3263 RECORDS 934020004 79014588 2052586 1233877 289153 10811800 VISITS 100.000 84.596 1.321 0.310 11.576 11.576 PERCENT ----------------------------------------------------------------------------- A. EMERGENCY DEPARTMENT PATIENT VISITS (cont.) NUMBER OF MEDICATIONS TOTAL NONE 1 DRUG 2 DRUGS 3 DRUGS ALL 26547 7001 8858 5678 2729 93402004 23881601 31373585 20403872 9641722 100.000 25.569 33.590 21.845 10.323 4 DRUGS 5 DRUGS 1102 1179 RECORDS 3969008 4132216 VISITS 4.249 4.424 PERCENT _____________________________________________________________________________ B. EMERGENCY DEPARTMENT DRUG MENTIONS PATIENT AGE TOTAL < 15 15-24 25-44 45-64 65-74 75+ ALL 38704 7818 5679 12224 6470 3032 3481 REC 137643607 29344993 19906808 42996205 22394770 10436732 12564099 MEN 100.000 21.320 14.463 31.237 16.270 7.582 9.128 PER ---------------------------------------------------------------------------- PATIENT SEX TOTAL FEMALE MALE ALL 38704 20769 17935 RECORDS 137643607 74174500 63469107 MENTIONS 100.000 53.889 46.111 PERCENT ----------------------------------------------------------------------------- B. EMERGENCY DEPARTMENT DRUG MENTIONS (cont.) NATIONAL DRUG CODE CLASSES TOTAL 01 02 03 04 ALL 38704 820 79 6351 456 137643607 3029937 261868 23099973 1499303 100.00 2.201 0.190 16.782 1.089 05 06 07 08 09 10 2504 2102 20 1840 733 1702 8828099 6988518 71427 6600680 2490278 5764510 6.414 5.077 0.052 4.795 1.809 4.188 11 12 13 14 15 16 1126 1289 984 35 662 310 4089650 4529308 3217310 115120 2490192 1233539 2.971 3.291 2.337 0.084 1.809 0.896 17 18 19 20 00 10713 56 4075 2719 128 RECORDS 38059676 178691 14757977 9892472 445079 MENTIONS 27.651 0.130 10.722 7.187 0.323 PERCENT 01 = Anesthetics, 02= Antidotes, 03 = Antimicrobial agents, 04 = Hematologic agents, 05 = Cardiovascular-renal drugs, 06 = Psychopharmacologic drugs, 07 = Radiopharmaceutical/contrast media, 08 = Gastrointestinal agents, 09 = Metabolic and nutrient agents, 10 = Hormones and agents affecting hormonal mechanisms, 11 = Immunologic agents, 12 = Skin/mucous membrane, 13 = Neurologic drugs, 14 = Oncolytics, 15 = Ophthalmic drugs, 16 = Otologic drugs, 17 = Drugs used for relief of pain, 18 = Antiparasitic agents, 19 = Respiratory tract drugs, 20 = Unclassified/miscellaneous, 00 = Unknown. ----------------------------------------------------------------------------- C. OUTPATIENT DEPARTMENT PATIENT VISITS PATIENT AGE TOTAL < 15 15-24 25-44 45-64 65-74 75+ ALL 29095 6572 4080 8441 5800 2361 1841 RECORDS 66345077 13516045 7833529 19814692 14305605 5955439 4919767 VISITS 100.000 20.372 11.807 29.866 21.562 8.976 7.415 PERCENT --------------------------------------------------------------------------- PATIENT SEX TOTAL FEMALE MALE ALL 29095 17870 11225 RECORDS 66345077 40599309 25745768 VISITS 100.000 61.194 38.806 PERCENT --------------------------------------------------------------------------- PATIENT RACE ASIAN/ AMERICAN PACIFIC INDIAN/ TOTAL WHITE BLACK ISLANDER ESKIMO/ALEUT ALL 29095 21356 6793 818 128 RECORDS 66345077 49700886 15132480 1283321 228390 VISITS 100.000 74.913 22.809 1.934 0.344 PERCENT --------------------------------------------------------------------------- ETHNICITY NOT TOTAL HISPANIC HISPANIC ALL 29095 4433 24662 RECORDS 66345077 11145112 55199965 VISITS 100.000 16.799 83.201 PERCENT --------------------------------------------------------------------------- C. OUTPATIENT DEPARTMENT VISITS (cont.) EXPECTED SOURCES OF PAYMENT PRIVATE/ OTHER TOTAL COMMERCIAL MEDICARE MEDICAID GOV'T ALL 29095 7213 4887 10245 980 66345077 18410790 11866960 20028609 2341690 100.000 27.750 17.887 30.189 3.530 HMO/OTHER PATIENT NO PREPAID PAID CHARGE OTHER UNSPECIFIED 2391 3237 462 1513 1184 RECORDS 7680399 7322975 923352 3558887 2520796 VISITS 11.576 11.038 1.392 5.364 3.800 PERCENT --------------------------------------------------------------------------- PATIENT REFERRAL STATUS TOTAL YES NO ALL 29095 6821 22274 RECORDS 66345077 13734496 52610581 VISITS 100.000 20.702 79.298 PERCENT --------------------------------------------------------------------------- VISIT NEW OLD PATIENT/ OLD PATIENT/ STATUS TOTAL PATIENT NEW PROBLEM OLD PROBLEM ALL 29095 6747 3997 18351 RECORDS 66345077 14164979 9921882 42258216 VISITS 100.000 21.350 14.955 63.695 PERCENT --------------------------------------------------------------------------- NUMBER OF MEDICATIONS TOTAL NONE 1 DRUGS 2 DRUGS 3 DRUGS ALL 29095 11713 7934 4495 2169 66345077 26068421 18863040 10148869 5152794 100.000 39.292 28.432 15.297 7.767 4 DRUGS 5 DRUGS 1212 1572 RECORDS 2784718 3327235 VISITS 4.197 5.015 PERCENT D. OUTPATIENT DEPARTMENT DRUG MENTIONS PATIENT AGE TOTAL < 15 15-24 25-44 45-64 65-74 75+ ALL 36139 6759 3486 9525 8961 4108 3300 REC 82394207 13818685 6585343 22580046 21902761 9849751 7657621 MEN 100.000 16.771 7.992 27.405 26.583 11.954 9.294 PER --------------------------------------------------------------------------- PATIENT SEX TOTAL FEMALE MALE ALL 36139 22504 13635 RECORDS 82394207 50508557 31885650 MENTIONS 100.000 61.301 38.699 PERCENT --------------------------------------------------------------------------- D. OUTPATIENT DEPARTMENT DRUG MENTIONS (cont.) NATIONAL DRUG CODE CLASSES TOTAL 01 02 03 04 ALL 36139 474 51 4267 771 82394207 614327 65756 10372645 1551021 100.00 0.746 0.080 12.589 1.882 05 06 07 08 09 10 4155 3227 273 1593 2224 3193 10420227 5697841 482554 3819410 4029211 8265348 12.647 6.915 0.586 4.636 4.890 10.031 11 12 13 14 15 16 1661 1717 1084 536 684 220 3312968 4352522 1888940 1203320 2224860 378801 4.021 5.283 2.293 1.460 2.700 0.460 17 18 19 20 00 4167 129 2955 2477 281 RECORDS 10313199 379987 7041399 5480031 499840 MENTIONS 12.517 0.461 8.546 6.651 0.607 PERCENT 01 = Anesthetics, 02= Antidotes, 03 = Antimicrobial agents, 04 = Hematologic agents, 05 = Cardiovascular-renal drugs, 06 = Psychopharmacologic drugs, 07 = Radiopharmaceutical/contrast media, 08 = Gastrointestinal agents, 09 = Metabolic and nutrient agents, 10 = Hormones and agents affecting hormonal mechanisms, 11 = Immunologic agents, 12 = Skin/mucous membrane, 13 = Neurologic drugs, 14 = Oncolytics, 15 = Ophthalmic drugs, 16 = Otologic drugs, 17 = Drugs used for relief of pain, 18 = Antiparasitic agents, 19 = Respiratory tract drugs, 20 = Unclassified/miscellaneous, 00 = Unknown. RELATIVE STANDARD ERRORS The standard error is primarily a measure of the sampling variability that occurs by chance because only a sample is surveyed, rather than the entire universe. The relative standard error (R.S.E.) of an estimate is obtained by dividing the standard error of the estimate by the estimate itself and is expressed as a percentage of the estimate. TABLE I. Relative standard errors for estimated numbers of patient visits and drug mentions: National Hospital Ambulatory Medical Care Survey, 1994. __________________________________________________________________________ ] PATIENT VISITS ] DRUG MENTIONS _____________________________________]____________________________________ ] Estimate Relative Standard Error ] Estimate Relative Standard Error (in 1000s) (in percent) ] (in 1000s) (in percent) _____________________________________]_____________________________________ ED OPD ] ED OPD _____________________________________]_____________________________________ ] 10 ....... 74.5 81.9 ] 10 ....... 93.1 91.7 20 ....... 52.8 58.7 ] 20 ....... 66.0 65.8 30 ....... 43.2 48.6 ] 30 ....... 54.0 54.4 40 ....... 37.5 42.6 ] 40 ....... 46.8 47.8 50 ....... 33.6 38.6 ] 50 ....... 42.0 43.3 63 ....... 30.0* 35.0 ] 70 ....... 35.6 37.5 91 ....... 25.1 30.0* ] 90 ....... 31.5 33.9 100 ....... 24.0 28.9 ] 100 ....... 30.0* 32.6 200 ....... 17.3 22.6 ] 124 ....... 27.0 30.0* 400 ....... 12.7 18.7 ] 400 ....... 15.8 21.2 1,000 ....... 8.8 15.8 ] 1,000 ....... 10.9 18.0 5,000 ....... 5.7 14.1 ] 5,000 ....... 7.1 16.1 10,000 ....... 5.2 13.8 ] 10,000 ....... 6.4 15.9 50,000 ....... 4.8 13.7 ] 50,000 ....... 5.9 15.7 100,000 ....... 4.7 13.6 ] 100,000 ....... 5.8 15.7 ____________________________________________________________________________ * The lowest reliable estimate. Example of use of table: An aggregate estimate of 1 million patient visits to OPDs has a relative standard error of 15.8%, or a standard error of 158,000 patient visits (15.8 percent of 1 million). For aggregate estimates, relative standard errors may be calculated using the following general formula, where "x" is the aggregate of patient visits or drug mentions in thousands, and coefficients "A" and "B" are obtained from table II: Divide coefficient B by x and add the result to coefficient A. Take the square root of that sum. Multiply that result by 100 to obtain the relative standard error of x expressed as a percent. For estimates of percentages, relative standard errors may be calculated using the following general formula, where "p" is the percent of visits or drug mentions, "x" is the denominator of the percent in thousands, and coefficient "B" is obtained from table II. Multiply coefficient B by (1 - p). Divide the result by the product of (p * x). Take the square root of that result. Multiply the new result by 100 to obtain the relative standard error of "p" expressed as a percent. Table II. Coefficients appropriate for determining approximate relative standard errors of patient visit and drug mention estimates (in thousands) for emergency departments and outpatient departments: National Hospital Ambulatory Medical Care Survey, 1994. Coefficient for use with estimates in thousands _____________________________ A B _________________________________________________________________ Patient visits Emergency Departments............... 0.002192 5.525659 Outpatient Departments.............. 0.018523 6.5287211 Drug mentions Emergency Departments............... 0.003289 8.6419155 Outpatient Departments.............. 0.024411 8.1609017 _________________________________________________________________ For estimates of visit rates, in which the numerator is the number of visits for a particular characteristic, and the denominator is the total United States population, the relative standard error is equivalent to the relative standard error of the numerator, as shown in the previous paragraph on aggregate estimates. DEFINITIONS OF TERMS USED IN THE SURVEY Patient - An individual seeking personal health services not currently admitted to any health care institution on the premises. A person under a physician's care for health reasons. Patients are defined as in scope or out of scope as follows: In scope - A patient seen by hospital staff in an in scope emergency service area or clinic except as excluded below. Out of scope - Patients seen by a physician in their private office, nursing home, or other extended care institution or in the patient's home. Patients who contact and receive advice from hospital staff via telephone. Patients who come to the hospital only to leave a specimen, to pick up insurance forms, to pick up medication, or to pay a bill. Visit - A visit is a direct, personal exchange between an ambulatory