Outcomes of patients with hypertension and non-insulin dependent diabetes mellitus treated by different systems and specialties. Results from the medical outcomes study

Abstract

OBJECTIVE: To compare the outcomes of patients with hypertension and non-insulin-dependent diabetes mellitus (NIDDM) who were cared for in three different systems of care and by generalist and subspecialist physicians. DESIGN: An observational study with follow-up at three periods: (1) a 2-year study of 532 patients with hypertension and 170 patients with NIDDM who had entrance and exit histories, physical examinations, and laboratory tests; (2) a 4-year follow-up of 1044 patients with hypertension and 317 patients with NIDDM based on patient-reported functional status; and (3) 7-year mortality for 1296 patients with hypertension and 424 patients with NIDDM. SETTING AND PARTICIPANTS: Patients sampled from health maintenance organizations, large multispecialty groups, and solo or single-specialty group practices in Boston, Mass, Los Angeles, Calif, and Chicago, Ill. Patients were designated as belonging to one of three systems of care: fee for service; prepaid patients in solo or small single-specialty groups or in large multispecialty group practices, referred to as independent practice associations; and staff-model health maintenance organizations. The principal providers were family practitioners, general internists, cardiologists, or endocrinologists. MAIN OUTCOME MEASURES: Physiological, functional, and mortality. For hypertension, we measured blood pressure and stroke incidence. For NIDDM, we measured blood pressure, glycosylated hemoglobin level, visual function, vibration sense, ulcers and infections in the feet, and albumin excretion rate. Functional outcomes were assessed using the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36). Mortality was assessed for the 7 years following the entrance examination. RESULTS: We found no evidence that any one system of care or physician specialty achieved consistently better 2-year or 4-year outcomes than others for patients with NIDDM or hypertension. Endocrinologists appeared to achieve better foot-ulcer and infection outcomes for patients with NIDDM, particularly when compared with family practitioners. However, no other specialist differences were found in any individual measures for either condition. Moreover, no adjusted mortality differences among systems or among physicians specialties were observed in the 7-year follow-up period. CONCLUSION: No meaningful differences were found in the mean health outcomes for patients with hypertension or NIDDM, whether they were treated by different care systems or by different physician specialists. Although prepaid medicine relies more heavily on generalist physicians than does fee for service, there is no evidence from these analyses that the quality of care of moderately ill patients with these two common disease was adversely affected. These findings must be viewed in light of the historically higher costs of fee-for-service medicine and of subspecialty physician practice.