MARKET INFLUENCES ON INTERNAL-MEDICINE RESIDENTS DECISIONS TO SUBSPECIALIZE

Background: Managed care reduces the demand for internal medicine subs pecialists, but little empirical information is available on how incre asing managed care may be affecting residents' training choices. Objec tive: To determine whether increased managed care penetration into an area where residents train was associated with a decreased likelihood that residents who completed general internal medicine training pursue d subspecialty training. Design: Secondary logistic regression analysi s of data from the 1993 cohort of general internal medicine residents. Setting: U.S. residency training sites. Participants: 2263 U.S. medic al school graduates who completed general internal medicine residency training in 1993. Measurements: The outcome variable (enrollment in su bspecialty training) was derived from the Graduate Medical Education T racking Census of the Association of American Medical Colleges (AAMC). Health maintenance organization (HMO) penetration (possible range, 0. 0 to 1.0; higher values indicate greater penetration) was taken from t he Interstudy Competitive Edge Database. Individual and medical school covariates were taken from the AAMC's Student and Applicant Informati on Management System database and the National Institutes of Health In formation for Management Planning, Analysis, and Coordination system. The U.S. Census division was included as a control covariate. Results: 980 participants (43%) enrolled in subspecialty training. Logistic re gression analyses indicated a nonlinear association between managed ca re penetration into a training area and the odds of subspecialization. Increasing managed care penetration was associated with decreasing od ds of subspecialization when penetration exceeded 0.15. The choice of subspecialty training increased as HMO penetration increased from 0 to 0.15. Conclusions: Local market forces locally influenced the career decisions of internal medicine residents, but the influence was small compared with the effects of age and sex. These results suggest that m arket forces help to achieve more desirable genera list-to-specialist physician ratios in internal medicine.