The Effect of Cost-Containment Policies on Rates of Coronary Revascularization in California

BACKGROUND: Lower rates of use of resources have been reported for the treatment of hospitalized patients covered by Medicaid than for privately insured patients. Cost-containment policies may exacerbate such differences in the use of hospital resources. We studied patients with ischemic heart disease who received care at nonfederal hospitals in California in 1983 (the year a Medicaid cost-containment program was implemented), in 1985, or in 1988. Within this sample of patients, we compared the rates of coronary revascularization (coronary-artery bypass surgery or coronary angioplasty) among patients covered by Medicaid, patients with private insurance covering fee-for-service care, and patients enrolled in a health maintenance organization (HMO). METHODS: Logistic-regression models were used to determine adjusted odds ratios for the use of coronary revascularization procedures in patients with different types of insurance, with control for demographic, clinical, and hospital characteristics. The study samples were made up of 49,167 patients in 1983, 47,809 in 1985, and 44,631 in 1988. RESULTS: The frequency of revascularization increased in all three insurance groups from 1983 to 1988, but it did so much faster in the fee-for-service and HMO groups than in the Medicaid group. Patients with private fee-for-service insurance were 1.66 times as likely as Medicaid patients to undergo revascularization in 1983 (P < 0.01), 2.01 times as likely in 1985 (P < 0.01) and 2.33 times as likely in 1988 (P < 0.01). Patients enrolled in HMOs were 0.96 times as likely as Medicaid patients to undergo revascularization in 1983 (P < 0.05), 1.23 times as likely in 1985 (P < 0.01), and 1.53 times as likely in 1988 (P < 0.01). CONCLUSIONS: The frequency of coronary revascularization in California in 1983 was nearly twice as high for patients with private fee-for-service insurance as for patients enrolled in HMOs or for Medicaid recipients. The implementation that year of stringent cost-control measures by Medicaid may explain the slower increase in the frequency of revascularization over five year among Medicaid recipients as compared with patients in the fee-for-service and HMO groups. Different incentives in fee-for-service and HMO practice may explain the lower frequency of revascularization among patients enrolled in HMOs, although the rates of increase for these two groups were about the same from 1983 to 1988.