Antipsychotics and risk of cerebrovascular events in treatment of behavioural and psychological symptoms of dementia in Hong Kong: a hospital-based, retrospective, cohort study.

Objective: The purpose of this study was to investigate the risk of cerebrovascular adverse events (CVAEs) in patients with behavioural and psychological symptoms of dementia (BPSD) treated with typical or atypical antipsychotics in Hong Kong

Method: This was a retrospective cohort study. Patients aged 65 or above, diagnosed with Alzheimer's disease, vascular or mixed dementia, and first attended the psychiatric service of our unit between 1st January 2000 to 30th June 2007 were studied. The patients were divided into three groups according to their antipsychotic usage. They were compared on sociodemographic and clinical characteristics. The risk of CVAEs was studied by means of Cox regression analysis.

Results: The studied cohort consisted of 1089 patients. The antipsychotic non-user, typical and atypical users groups consisted of 363, 654 and 72 patients, respectively. Incidence rate of CVAE for the three groups were 44.6/1000, 32.7/1000 and 49.6/1000 person years, respectively. The risk of developing CVAEs did not differ in typical or atypical antipsychotic user groups compared with non-user group. The adjusted hazard ratio of typical and atypical antipsychotic user groups were 0.964 (95% CI = 0.584-1.591) and 1.036 (95% CI = 0.350-3.066), respectively. Subgroup analyses of individual antipsychotic did not show a significant increase in risk of CVAEs.

Conclusion: This study showed that there was no statistical difference in risk of cerebrovascular events in treatment of BPSD with typical and atypical antipsychotics compared with non-user group. Nonetheless, given the side effects of antipsychotics, prescription of antipsychotics should be reserved for severe and distressing symptoms with careful consideration.