Effect of a mental health "carve-out" program on the continuity of antipsychotic therapy

On July 1, 1996, as a cost-containment strategy, Tennessee's expanded Medicaid program, TennCare, rapidly shifted the provision of mental health services to a fully capitated, specialty "carve-out" program, TennCare Partners. We studied the effect of this transition on the continuity of antipsychotic therapy among patients with severe mental illness who had previously adhered to treatment.

Study patients were 21 to 64 years of age, were enrolled throughout the study period, and had adhered to antipsychotic therapy during a 6-month base-line period that preceded the 12 months of study follow-up. The study population included 4507 patients whose follow-up began on the day the change was implemented (the post-transition cohort) and 3644 patients whose follow-up began one year earlier (the pretransition cohort). We compared the two cohorts in terms of the loss of continuity of antipsychotic therapy (missed treatment for more than 60 days during follow-up) and the mean number of days of antipsychotic therapy during follow-up.

As compared with the pretransition cohort, the post-transition cohort had increased odds of loss of continuity (a multivariate odds ratio of 1.18 [95 percent confidence interval, 1.07 to 1.30], P=0.001) and a shorter mean duration of antipsychotic therapy (a mean reduction of 4.2 days [95 percent confidence interval, 1.7 to 6.7], P=0.001) during follow-up. This difference was most pronounced among high-risk patients (those requiring the administration of extended-release [depot] injections of antipsychotic medications or who had been hospitalized for psychosis) at base line, for whom continuity was most important (odds ratio for loss of continuity, 1.79 [95 percent confidence interval, 1.45 to 2.22]; P<0.001; mean reduction in the number of days of antipsychotic therapy, 14.4 days [95 percent confidence interval, 9.4 to 19.4]; P<0.001). These patients had decreased use of antipsychotic drugs immediately after the transition; the lower level persisted throughout the 12 months of follow-up.

These findings underscore the need to ensure that shifts to widely used carve-out programs, which are designed primarily to contain costs, do not adversely affect clinical outcomes.