Enrollment in and disenrollment from health maintenance organizations by Medicaid recipients.

In 1977-78 Medicaid recipients in Wayne County, Michigan had the option of joining health maintenance organizations (HMO's). This article presents an analysis of utilization levels and physician contact patterns prior to HMO enrollment and following HMO disenrollment. Medicaid families that had patterns of previous contacts with non-HMO physicians overwhelmingly choose the non-HMO option. Families with no physician contacts and very low utilization levels selected the HMO's. Also, higher than average utilization occurred during the 3 months following disenrollment from these HMO's.