Risk of venous thromboembolism among women receiving ospemifene: a comparative observational study
Authors: Nordstrom Beth L. , Cai Bin , De Gregorio Fabio , Ban Lu , Fraeman Kathy H. , Yoshida Yuki , Gibbs Trevor 
Published: November 2022

Introduction: The primary aim of this study was to compare the incidence of venous thromboembolism (VTE) among women initiating ospemifene vs other selective estrogen receptor modulator (SERM) therapies for estrogen-deficiency conditions or breast cancer prevention, and vs women with untreated vulvar and vaginal atrophy (VVA). The secondary objective examined numerous additional safety outcomes. Methods: This was a retrospective cohort study using the IBM Watson MarketScan claims database. Women receiving ospemifene, another SERM, or with a new diagnosis of VVA with no treatment from 1 May 2013 to 2 October 2018 were followed through the claims for incident adverse outcomes. The primary outcome was the first occurrence of VTE following cohort entry; secondary outcomes included cerebrovascular events and other adverse events potentially associated with SERM use. Cox models compared the risk of VTE between ospemifene and comparators, using a variety of approaches to control for confounding. Results: The incidence of VTE during the first continuous treatment episode was 3.39 (95% confidence interval [CI]: 1.55–6.43) events per 1,000 person-years (PY) for ospemifene ( N = 8977), 11.30 (95% CI: 8.81–14.28) events per 1,000 PY for comparator SERM ( N = 12,621), and 10.92 (95% CI: 10.49–11.37) events per 1,000 PY for untreated VVA ( N = 242,488). Cox models indicated no increase in risk of VTE for ospemifene vs other SERMs (hazard ratio [HR]: 0.40, 95% CI: 0.19–0.82), and vs untreated VVA (HR: 0.47, 95% CI: 0.24–0.91). Conclusion: This real-world safety analysis found no increase in risk of VTE or other adverse events with use of ospemifene in postmenopausal women. Plain Language Summary Introduction: This study assessed the risk of venous thromboembolism (VTE) among women treated with ospemifene or another selective estrogen receptor modulator (SERM) therapy and women with untreated vulvar and vaginal atrophy (VVA). Numerous additional safety outcomes were examined. Methods: This study was conducted in the IBM Watson MarketScan claims database. Women receiving ospemifene, another SERM, or with a new diagnosis of VVA with no treatment from 1 May 2013 to 2 October 2018 were followed through the claims for adverse outcomes, including VTE, cerebrovascular events (such as stroke), and other outcomes that might occur with use of a SERM. The analyses compared the risk of VTE between ospemifene and the other two groups, using methods that accounted for differences in patient characteristics between the groups. Because few women over 72 years old used ospemifene, the main analyses examined women aged 54–72 years. Results: The analyses included 8,977 ospemifene users, 12,621 other SERM users, and 242,488 women with untreated VVA. Among women aged 54–72 years, only 9 experienced a VTE during ospemifene treatment, while 55 other SERM users and 1,788 women with untreated VVA had a VTE. The analyses that accounted for differences between the groups confirmed that the risk of VTE was no higher in ospemifene users than in either comparison group. Conclusion: This real-world safety analysis found no increase in risk of VTE or other adverse events with use of ospemifene in postmenopausal women.