In a controlled trial of the effects of medical insurance on spending and health status, we previously reported lower average (0.8 mm Hg) diastolic blood pressures with free care than with cost-sharing plans. We show herein that for clinically defined hypertensives, blood pressures with free care were significantly lower (1.9 mm Hg) than with cost-sharing plans, with a larger difference for low-income hypertensives than for high-income hypertensives (3.5 vs 1.1 mm Hg), but similar differences for blacks and whites. The cause of the difference was the additional contact with physicians under free care; this led to better detection and treatment of hypertensives not under care at the start of the study. Free care also led to higher compliance by hypertensives with diet and smoking recommendations and higher use of medication by those who needed it.
Keeler EB, Brook RH, Goldberg GA, Kamberg CJ, Newhouse JP. How Free Care Reduced Hypertension in the Health Insurance Experiment. JAMA. 1985;254(14):1926-1931. doi:10.1001/jama.1985.03360140084030