Self-Reported Physician Specialties and the Primary Care Content of Medical Practice

BACKGROUND: Many internal medicine physicians report both primary and secondary specialties in the American Medical Association (AMA) Physician Masterfile. Usually, those represent combinations of general internal medicine and medical subspecialty practice. Whether reported specialty combinations can be used to assess the contribution of specialists to primary care is unknown. OBJECTIVES: To examine whether internists' primary and secondary specialties reported in the Masterfile reflect the amount of primary care that they provide, and whether changes over time in internists' reported specialties reflect changes in primary care provision. DESIGN: The Masterfile was used to identify internists' reported specialties in 1992 and in 1996. A mail questionnaire was used to assess the primary care content of physicians' practices. The association between reported specialties and the amount of primary care provided was evaluated using analysis of variance. SUBJECTS: A stratified random sample of internists in active clinical practice. MEASURES: The percentage of visits which were for the general medical care of patients for whom the physicians maintained ongoing responsibility. In addition, how often the physicians initiated the provision of preventive care for their regular patients, provided general medical care to these patients, and organized and coordinated the care received by these patients from other providers. RESULTS: There was a strong association between the internists' primary and secondary specialties reported in the Masterfile and measures of the primary care content of physicians' practices (P < 0.0001). In contrast, changes over time in internists' reported specialties were not associated with physicians' assessments of changes in the primary care content of their practices. CONCLUSIONS: Aggregate estimates of the availability of primary care in the US could be adjusted by taking into account the primary and secondary specialties reported by internal medicine physicians in the AMA Physician Masterfile.