Impact of a prescription drug copayment policy on prescription drug and health services utilization in an Oregon Medicaid population. Health care costs associated with the Medicaid program have become a significant burden to individual states across the county. Prescription drugs are a key driver of these costs and as such have been focus of a wide variety of cost-containment policies. Copayments (co-pays) for prescription drugs are a particularly common strategy aimed at controlling costs among Medicaid programs. However, little is known about the impact of copay policies on Medicaid patients on medication use as well as health status. The goals of this analysis were to quantify the impact of the copay policy for prescription drugs on medication and health services utilization in the Oregon Medicaid program.