Comparative Risk of Cerebrovascular Adverse Events in Community-Dwelling Older Adults using Risperidone, Olanzapine and Quetiapine A Multiple Propensity Score-Adjusted Retrospective Cohort Study

Background Atypical antipsychotic agents have been associated with cerebrovascular adverse events, particularly in elderly dementia patients. However, limited evidence exists regarding comparative cerebrovascular profiles of individual atypical agents, particularly in community settings. Objective The objective of this study was to evaluate the risk of cerebrovascular events associated with use of risperidone, olanzapine and quetiapine in community-dwelling older adults in the US. Methods A propensity score-adjusted retrospective cohort design involving the IMS LifeLink (TM) Health Plan Claims Database was used for the study. The study population included all older adults (aged >= 50 years) who initiated risperidone, olanzapine or quetiapine anytime during 1 July 2000 to 30 June 2008. Patients were followed until hospitalization or an emergency room visit for a cerebrovascular event, or the end of the study period, whichever occurred earlier. The Cox proportional hazard regression model with time-varying covariates was used to evaluate the risk of cerebrovascular events during the follow-up period, using olanzapine as the reference. The covariates adjusted for in the final model included multiple propensity scores and exposure to other medications that could be associated with the risk of cerebrovascular events. Results A total of 2,458 cerebrovascular events were identified in the study cohort: 1,081 (21.38 %) for risperidone users, 816 (18.75 %) for olanzapine users and 561 (21.05 %) for quetiapine users. After adjusting for propensity scores and other covariates, the Cox proportional hazard model revealed that use of quetiapine [hazard ratio (HR) 0.88; 95 % CI 0.78, 0.99] but not risperidone (HR 1.05; 95 % CI 0.95, 1.16) was associated with a decrease in the risk of cerebrovascular adverse events compared with olanzapine. Conclusions The study suggested that quetiapine use may be associated with a moderately lower risk of cerebrovascular events than olanzapine in older adults. Prescribers should closely monitor the patients treated with atypical agents for the incidence of cerebrovascular adverse events.