Medical care costs and hospitalization in patients with bipolar disorder treated with atypical antipsychotics.

BACKGROUND A large proportion of costs associated with the treatment of bipolar disorder are attributable to patient hospitalization. OBJECTIVE To investigate medical care costs and hospitalization rates among patients with bipolar disorder who were managed with aripiprazole compared with olanzapine, quetiapine, risperidone, or ziprasidone. METHODS This retrospective cohort study assessed patients who were aged 18 to 64 years, diagnosed with bipolar disorder, and who were receiving therapy with aripiprazole, olanzapine, quetiapine, risperidone, or ziprasidone. This study was based on data from the PharMetrics claims database between January 1, 2003, and September 30, 2008. The study used a time-to-event framework. Cox proportional hazards models were used to assess the impact of each atypical antipsychotic on time to hospitalization, including all-cause and mental health-related reasons. Generalized linear models were used to compare costs per treated patient per month between the groups. Aripiprazole therapy was the reference group for all comparisons. RESULTS Aripiprazole therapy showed a significantly lower hazard ratio (HR) for all-cause hospitalizations compared with olanzapine (HR, 1.4), quetiapine (HR, 1.4), risperidone (HR, 1.2), and ziprasidone (HR, 1.7); and for mental health-related hospitalizations compared with olanzapine, quetiapine, risperidone (HR, 1.3 each), and ziprasidone (HR, 1.7). Ziprasidone had higher unadjusted all-cause medical costs (US $1151 ± $2928) and unadjusted mental health-related costs (US $711 ± $2263) than the other antipsychotics that were included in this study, whereas aripiprazole had the lowest all-cause (US $804 ± $2523) and mental health-related costs (US $475 ± $2145) compared with the other antipsychotics. Quetiapine had the highest all-cause costs (US $1221; 95% confidence interval [CI], 1180-1263), and ziprasidone had the highest mental health-related costs (US $823; 95% CI, 754-898). Adjusted inpatient and emergency department all-cause costs were significantly lower for aripiprazole compared with all other atypical antipsychotics (P <.05), except olanzapine; however, the adjusted inpatient and emergency department mental health-related costs were significantly lower for aripiprazole only when compared with ziprasidone (P <.05). CONCLUSIONS The costs of medical care for patients with bipolar disorder differ based on the type of medication used, which can affect the rate of hospitalization. Treatment with aripiprazole was associated with fewer hospitalizations, longer time to hospitalization, and therefore the lowest all-cause and mental health-related medical costs compared with olanzapine, quetiapine, risperidone, or ziprasidone. Therefore, aripiprazole may offer an economic advantage over other atypical antipsychotics in patients with bipolar disorder.