Public Use Data Ta~e Documentation 1992 National Ambulatory Medical Care Survey From the CENTERS FOR DISEASE CONTROL AND PREVENTION/Nutional Center for Health Stdklics -—..—=-.=-=.-.‘,.- . ----. - . .- -,-- -.-- .--.,. -’ ‘ --- - –.--.------ ,-:-.-,J ----- ---------- ---P ------.-->- — .. ..- --. : _ U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES Publlc Health Service Centers for Disease Control and Prevention National Center for Health Statistics CDCcE141EmFonmEUEcoumoL WMEmmm Public Use Data Tape Documentation 1992 National Ambulatory Medical Care Survey U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES Public Health Service Centers for Disease Control and Prevention National Center for Health .SJatistics Hyattsville, Maryland November 1994 299 2 NAMcs MICRO-DATA TAPE Docum NTATION PAGE 1 ABSTRACT This material provides documentation for users of the Micro-Data tapes of the National Ambulatory Medical Care Suney (NAMCS) conducted by the National Center for Health Statistics. Section I, “Description of the National Ambulatory Medical Care Sumey,” includes information on the scope of the amm.rey,the sample, field activities, data collection procedures, medical coding procedures, population estimates, and sampling errors. Section II provides technical detaile of the tape (number of tracks, record length, etc.), and a detailed description of the contents of each data record by location. Section III contains marginal data or estimates for each item on the data record in Section II. The appendixes contain santplingerrors, instructions and definitions for completing the Patient Record Form, and list~ of codes used in the survey. TABLE OF CONTENTS PAGE I. Description of the National Ambulatory Medical Care SuNey 2-14 Distribution of physicians (Table I) 4 Population Figures (Table II) 6 Patient Log and Patient Record Form (Figure 1) 8 References 14 II. Technical description of tape and record format 15-26 List of designated specialties 27-28 III. Marginal Data ED patient visits and drug mentions 29-30 OPD patient visits and drug mentions 31-32 Appendix I Relative Standard Errors (Tables III, IV, and V) 33-36 Instructions for completing Patient Record Forms 37-43 Definitions of certain terms used in the suney 44-45 Appendix II ‘Reason for Visitm Classification 46-69 Appendix III List of drug entry names and codes 70-78 List of generic names and codes 79-86 List of 20 drug classes, names and codes 87 User questionnaire a9-90 PAGE 2 1992 S MICRO-DATA TAPE DOCUhQ$lTATION I. DESCRIPTION OF THE NATIONAL AMBULATORY MBDICAL CARE SURVBY INTRODUCTION This 14icro-DataTape comprises the data collected by the National Ambulatory Medical Care Survey (NAMCS) in 1992, conducted by the National Center for Health Statistics (NCHS). The National Ambulatory Medical Care Survey provides data from samples of patient records selected from a national sample of office-based physicians. These national estimates describe the utilization of ambulatory medical care services in the United States. In 1992 there were 34,606 patient records provided by 1,558 doctors that participated in the survey. For a brief description of the sunrey design and data collection procedures, see below. For a more detailed description of the sunfey design, data collection procedures, and the estimation process see references 1 and 9. There are two important points relative to analyzing data from this micro-data tape that should be noted: l-Micro-data tape 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 13. 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 su~eys of the &nerican people, considers an estimate to be reliable if it has a relative standard error of 30* or less. 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 tape users can obtain an adequate working knowledge of the relative standard error from the information presented in the Appendix. If you would like more information, do not hesitate to consult the staff of the Ambulatory Care Statistics Branch. J99 2 NAMcs mm O-DATA TAPE DOCUMENTATION PAGE 3 SCOPE OF THE SURVEY The basic sampling unit for the WCS is the physician-patient encounter or visit. Only visits in the offices of nonfederally employed phyaiciana claaaified by the American Medical Association (AMA) or the American Osteopathic Association (AOA) as “office-based, patient care” were included in the 1992 NAMCS. In addition, phyBiCiana in the specialties of aneatheBiology, pathology, and radiology were excluded from the physician universe. Major types of ambulatory encounters not included in the 1992 NAMCS were those made by telephone, those made outside of the phyBician’E office, and those made in hospital or institutional aettinga. SAMPLING FRAME AND SIZE OF SAMPLE The sampling frame for the 1992 NAMCS was composed of all physicians contained in the maater files maintained by the AMA and AOA aa of December 31, 1991, who met the following criteria: Office-baaed, aa defined by the AMA and AOA: Principally engaged in patient care activities; Nonfederally employed; Not in apecialtiea of aneatheaiology, pathology, and radiology. The 1992 NAMCS sample included 3,000 physicians: 2,762 Medical Doctors and 238 Doctors of Osteopathy. Sample phyaiciana were screened at the time of the aumey to aaaure that they met the above-mentioned criteria. Eight hundred fifty-eight (858) phyaiciana did not meet all of the criteria and were, therefore, ruled out of scope (ineligible) for the study. The moat frequent reasona for being out of scope were that the physician was retired, deceased, or employed in teaching, research, or administration. Of the 2,142 in-scope (eligible)physicians, 73 percent participated in the study. The physician universe, sample size, and reaponae ratea by physician specialty are shown in table I. Of the participating phyaiciana, 266 aaw no patienta during their assigned reporting period because of vacationa, illneBs, or other reaaons for being temporarily not in practice. Table I. Distribution of physicians in the universe and in the 1992 National Ambulatory Medical Care SUPW2Y sample by physician specialty and response status: United States, 1992. NAMCS out of In Non - Response Universe* Sample Scope SEQ12!2 Response Response Rate** All Specialties 351,005 3000 858 2142 504 1550 73% General/Family Practice 57,364 164 48 116 25 91 78% Osteopathy 15,391 230 55 183 55 12B 70% Intef”nal MedIcIIw 51,559 157 44 113 37 76 67% Pediatrics 28,947 140 43 97 21 76 78% General Surgery 20,694 617 210 407 94 313 77% Obstetrics E Gynecology 26,690 112 26 86 19 67 78% Orthopedic Surgery 15,736 120 24 96 27 69 72% Cardiovascular Disease 11,332 147 29 110 45 73 62% Dermatology 6,246 104 19 85 35 50 59% Urology 7,597 126 31 95 21 74 70% Psychiatry 24,490 227 72 155 20 127 B 2% Neurology 6,257 213 68 145 3t3 107 74% Ophthalmology 13,605 114 16 9B 33 65 66% Otolaryngology 6,558 173 39 134 44 90 67% All other specialties 58,539 348 134 214 62 152 71% ●These data are derived from the American Medical Association and the American Osteopathic Association and represent the total number of physicians who are el igible for NAMCS. ** Response rate (percent) = response divided by in-scope. 1992 NAMCS MICRO-DATA TAPE DOCUMENTATION PAGE 5 SAMPLE DESIGN The 1992 NAMCS utilized a multistage probability design that involved probability samples of primary sampling units (PSU’S), physician practices within PSU’s, and patient visits within practices. The first-stage sample included 112 PSU’S. A PSU is a county, a group of adjacent counties, or a standard metropolitan statistical area (SMSA) . The second stage consisted of a probability sample of practicing physicians selected from the master files maintained by the American Medical Association (AMA) and American Osteopathic Association (AOA). Within each PSU, all eligible physicians were stratified by fifteen specialty groups: general and family practice, osteopathy, internal medicine, pediatrics, general surgery, obstetrics and gynecology, orthopedic surgery, cardiovascular diseases, dermatology, urological surgery, psychiatry, neurology, ophthalmology, otolaryngology, and all other specialties. The final stage was the selection of patient visits within the annual practices of sample physicians. This involved two steps. First, the total physician sample was divided into 52 random subsamples of approximately equal size, and each subsample was randomly assigned to 1 of the 52 weeks in the survey year. Second, a systematic random sample of visits was selected by the physician during the assigned week. The sampling rate varied for this final step from a 100-percent sample for very small practices to a 20-percent sample for very large practices as determined in a presurvey interview. The method by which the sampling rate was determined is described in reference 3. 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, 1992, provided