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

Abstract

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.

Keywords: bipolar disorder; lithium; manic; readmission; valproate.