Background: One of the principal tenets of managed care is that physicians' clinical decisions can be influenced both to improve the quality and consistency of care and to decrease health care expenditures. Medical decision making, however, remains a complex phenomenon and the most important determinants of physicians' approaches to clinical decision making remain poorly understood.
Objectives: To determine how clinical decisions are associated with individual characteristics, practice setting and organizational characteristics, attributes of the patient population under care, and the market environment.
Research design: Cross-sectional, nationally representative survey of patient-care physicians.
Subjects: Primary care physicians who provide direct patient care at least 20 hours per week.
Measures: Proportion of physicians who would order a referral, diagnostic test, or treatment for 5 clinical scenarios thought to be representative of discretionary medical decisions.
Results: Responses were received from 4,825 primary care physicians who cared for adult patients (Response Rate 65%). The distribution of results for each of the five clinical scenarios demonstrates significant variability both within and between physicians. No evidence was seen of a consistent practice style across the vignettes (eg, "aggressive" or "conservative"). The organizational setting of practice was the most consistent predictor of behavior across all the clinical scenarios, with the exception of back pain, which was minimally related to any of the environmental factors. When compared to physicians in solo practice, physicians in all other practice settings were less likely to order a test or referral or pursue treatment. Practice involvement with managed care and measures of financial influences and administrative strategies associated with managed care were minimally and inconsistently associated with reported physician behaviors.
Conclusions: The ability of managed care to improve the quality and consistency of care while also controlling the costs of care depends on its ability to influence medical decisions. Our findings generally demonstrate that managed care has a weak influence on discretionary medical decisions and that the influence of managed care pales in comparison to personal and practice setting influences.