Use of antipsychotics and risk of venous thromboembolism in postmenopausal women. A population-based nested case-control study.

Despite continued uncertainty of venous thromboembolism (VTE) caused from antipsychotic agents, this safety issue has not been examined in postmenopausal women, a population with high usages of antipsychotics and at high risk for VTE. We assessed whether antipsychotic use was associated with an increased VTE risk in women after menopause. We conducted a nested case-control study of all Taiwanese women aged ≥ 50 years (n = 316,132) using a nationwide healthcare claims database between 2000 and 2011. All newly diagnosed VTE patients treated with an anticoagulant or thrombectomy surgery were identified as cases (n = 2,520) and individually matched to select controls (n = 24,223) by cohort entry date, age, cancer diagnosis and major surgery procedure. The odds ratios (ORs) and 95 % confidence interval (CI) of VTE associated with antipsychotics were estimated by multivariate conditional logistic regressions. Current use of antipsychotics was associated with a 1.90-fold (95 % CI = 1.64-2.19) increased VTE risk compared with nonuse in postmenopausal women. The VTE risk existed in a dose-dependent fashion (test for trend, p<0.001), with a more than quadrupled risk for high-dose antipsychotics (adjusted OR = 4.60; 95 % CI = 2.88-7.33). Current parenteral administration of antipsychotics also led to a 3.46-fold increased risk (95 % CI = 2.39-5.00). Conversely, there was no increased VTE risk when antipsychotics were discontinued for > 30 days. In conclusion, current use of antipsychotics is significantly associated with a dose-dependent increased risk of VTE in postmenopausal women, especially for those currently taking high-dose or receiving parenteral antipsychotics.