Self-reported physician specialties and the primary care content of medical practice - A study of the AMA Physician Masterfile

BACKGROUND. Many internal medicine physicians report both primary and secon dary specialties in the American Medical Association (AMA) Physician Master file. Usually, those represent combinations of general internal medicine an d medical subspecialty practice. Whether reported specialty combinations ca n be used to assess the contribution of specialists to primary care is unkn own. OBJECTIVES. TO examine whether internists' primary and secondary specialtie s reported in the Masterfile reflect the amount of primary care that they p rovide, and whether changes over time in internists' reported specialties r eflect changes in primary care provision. DESIGN. The Masterfile was used to identify internists' reported specialtie s in 1992 and in 1996. A mail questionnaire was used to assess the primary care content of physicians' practices. The association between reported spe cialties and the amount of primary care provided was evaluated using analys is of variance. SUBJECTS. A stratified random sample of internists in active clinical pract ice. MEASURES. The percentage of visits which were for the general medical care of patients for whom the physicians maintained ongoing responsibility. In a ddition, how often the physicians initiated the provision of preventive car e for their regular patients, provided general medical care to these patien ts, 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 prima ry care content of physicians' practices (P < 0.0001). In contrast, changes over time in internists' reported specialties were not associated with phy sicians' assessments of changes in the primary care content of their practi ces. CONCLUSIONS. Aggregate estimates of the availability of primary care in the US could be adjusted by taking into account the primary and secondary spec ialties reported by internal medicine physicians in the AMA Physician Maste rfile.