One-year rehospitalization rates of patients with first-episode bipolar mania receiving lithium or valproate and adjunctive atypical antipsychotics

Aim We compared the 1-year rehospitalization rates of first-episode bipolar manic patients who were discharged while being treated with lithium or valproate in combination with an atypical antipsychotic. Methods We investigated the rehospitalization status of first-episode bipolar manic patients who were discharged between 1 January 2003 and 31 December 2010 while they were taking lithium or valproate in combination with aripiprazole, olanzapine, quetiapine, or risperidone. Rehospitalization rates during a 1-year period after discharge were compared between the group receiving lithium plus an atypical antipsychotic and the group receiving valproate plus an atypical antipsychotic using the Kaplan-Meier method. A Cox regression model was used to analyze covariates hypothesized to affect time to rehospitalization. Results The rehospitalization rate was 17.3% during the 1-year follow-up period. We found significant differences in the rehospitalization rates of patients in the lithium (23.1%) and the valproate (13.3%) groups using the Kaplan-Meier formula. According to Cox proportional hazards regression analysis, higher Clinical Global Impression-Bipolar Version-Severity score at discharge (P = 0.005) and lithium treatment (P = 0.055) contributed to the risk of rehospitalization. Conclusion Treatment with valproate and an atypical antipsychotic can be more effective than treatment with lithium and an atypical antipsychotic in preventing rehospitalization during the 1 year after hospitalization due to a first manic episode in patients with bipolar I disorder. Higher Clinical Global Impression-Bipolar Version-Severity scores at discharge also negatively affected rehospitalization rates.