The impacts of mental health parity and managed care in one large employer group.

We examine the impacts of a state mental health parity mandate on a large employer group, which simultaneously introduced a managed behavioral health care carve-out. Overall, we find that mental health/substance abuse (MH/SA) costs dropped 39 percent from the year prior to three years after parity, with managed care offsetting increases in demand induced by parity coverage. Managed care was most effective in reducing very high inpatient use among adolescents and children. The effect of the parity mandate on access was ambiguous: While treatment prevalence rose nearly 50 percent, similar increases were observed for groups not subject to the mandate.