Commercial plans in Medicaid managed care: understanding who stays and who leaves.

Although the rapid increase in Medicaid managed care during the early 1990s attracted commercial plans to the program, by the late 1990s commercial plan participation in Medicaid had begun to decline. This study examines the role of Medicaid policies, plan characteristics, and local health care market conditions in a commercial plan's decision to exit. We find that many of the factors that influence commercial plans' decisions to exit Medicaid are within the control of state policymakers and program administrators, including capitation rates, service carve-outs, mandatory enrollment policies, and the number of Medicaid enrollees and areas served by the plan.