Initiation of statins and risk of venous thromboembolism: Population-based matched cohort study.

Background: The effects of statins in prevention of venous thromboembolism (VTE) is not well established. Objectives: To examine the risks of first-time VTE in a cohort of patients initiating statin treatment and in a matched general population comparison cohort. Methods: We conducted a nationwide, population-based, matched cohort study based on data from Danish health registries. The study period was 1 January 2005-31 December 2015. We identified statin initiators (without VTE, myocardial infarction, or ischemic stroke) and sex-, age-, and calendar year-matched (1,3) individuals from the general population (without statin use, VTE, myocardial infarction, or ischemic stroke). We computed cumulative risks and comorbidity-adjusted hazard ratios (HRs) of VTE, myocardial infarction, and ischemic stroke. Results: Among 601,011 statin initiators and 1,803,033 matched population cohort members during 2005-2015, the cumulative risk after 11 years was 2.8% for VTE (both cohorts), 4.7% vs. 2.9% for myocardial infarction, and 7.1% vs. 5.2 for ischemic stroke. After adjustment, statin use was associated with a slightly decreased risk of VTE (adjusted HR: 0.95 [95% CI: 0.92-0.97]), driven by a reduced risk of unprovoked VTE (adjusted HR: 0.92 [95% CI: 0.89-0.95]). The reduced risks of VTE were more pronounced among patients who had an imaging examination performed. The adjusted HRs were elevated for myocardial infarction and ischemic stroke. Conclusion: Statin initiation was associated with a reduced risk of VTE, with no indication of a healthy-user effect. Based on available evidence, statins have weak thromboprophylactic effects.