Antipsychotic drug use and the risk of venous thromboembolism in elderly patients with dementia.

The aim of this study was to investigate the association between the use of antipsychotics and the risk of venous thromboembolism (VTE) in elderly patients with dementia. Based on data from the German Pharmacoepidemiological Research Database, a nested case-control study was conducted within a cohort of 72,591 patients with dementia aged at least 65 years at cohort entry. Cases were patients with a hospitalization due to VTE. Up to 4 controls were matched to each case according to age, sex, health insurance, and calendar time of the VTE. Users of antipsychotics were classified into current or former users, and in addition, all current users were categorized as prevalent or new users. For a further analysis, we distinguished between users of either conventional or atypical antipsychotics or concurrent users of both conventional and atypical antipsychotics. Multivariate conditional logistic regression was applied to calculate odds ratios (ORs) of VTE for all user groups compared with nonusers. The case-control data set comprised 1028 VTE cases and 4109 controls. An increased risk of VTE was found for current users (OR, 1.23; 95% confidence interval [CI], 1.01-1.50) and for users of a combination of atypical and conventional antipsychotics (OR, 1.62; 95% CI, 1.15-2.27). In current users, only new use was associated with an increased risk (OR, 1.63; 95% CI, 1.10-2.40). Increased attention to clinical signs of VTE should be paid during the first 3 months of treatment with antipsychotics and in patients receiving both conventional and atypical agents, especially if other risk factors for VTE exist.