Effects of changing Medicaid fees on physician participation and enrollee access.

This paper assesses the effects of Medicaid fee changes on physician participation, enrollee access, and shifts in the site of ambulatory care using several natural experiments in Maine and Michigan. We use Medicaid claims and enrollment data to measure these outcomes. The reimbursement changes included substantial percentage changes in fees, however the value of the Medicaid fee improvements relative to the private market eroded very rapidly in the months following the interventions. Although the fee increases did not improve the outcome measures, they might have prevented conditions from worsening.