Hormone therapy and risk of venous thromboembolism among postmenopausal women in Taiwan - a 10-year nationwide population-based study.

BACKGROUND: The incidence of venous thromboembolism (VTE) in Asians is lower than in Caucasians, but the risk of VTE associated with hormone therapy (HT) in Taiwanese postmenopausal women has not been determined. METHODS AND RESULTS: From Taiwan's National Health Insurance Research Database, we established matched cohorts (HT users and nonusers) of postmenopausal women aged ≥50 years between 1 January 1998 and 31 December 2008. We calculated the 2-year incidence of VTE in HT users and nonusers. HT users and nonusers were matched 1:1 based on propensity-score matching. Cox regression hazard model was used to identify risk factors of VTE. We initially identified 499,594 HT users and 424,963 nonusers. There were higher percentages of cancer and cardiovascular events among the HT nonusers. After matching, the VTE incidence was 4.4 vs. 2.6 per 10,000 patient-years (adjusted hazard ratio 1.796, 95% confidence interval 1.272-2.537) in HT users and nonusers, respectively. The Cox regression hazard model showed that HT use, older age, malignancy, heart failure, and recent major surgery were independent risk factors for VTE. CONCLUSIONS: Although the incidence of VTE was very low among this cohort of Taiwanese postmenopausal women, oral HT was still associated with an increased risk of VTE. Therefore, physicians should be aware of other potential VTE risk factors when prescribing oral HT to postmenopausal women.