Statin use and risk of recurrent venous thrombosis: results from the MEGA follow-up study

Introduction: Whether statin use after first venous thrombosis reduces the risk of recurrence is uncertain. Therefore, we aimed to examine the risk of recurrent venous thrombosis in statin users vs non-users. Methods: Patients with a first venous thrombosis were recruited from the MEGA follow-up study. Information on statin use was obtained by linkage to the Dutch Foundation for Pharmaceutical Statistics register. Linkage was successful in 54% of all patients (n = 2,547). Cox-regression models with statin-exposure as a time-dependent co-variate were used to estimate hazard ratios (HR) with 95% confidence intervals (CI 95) for recurrence. Results: Statin therapy was continued in 153 (6.0%) patients and initiated in 233 (9.1%) patients during a median follow-up of 5.7 years. There were 367 recurrent venous thrombotic events, of which 32 occurred among statin users. Incident statin use was associated with 22% reduced risk of recurrence after multivariable adjustments (HR 0.78, CI 95: 0.46-1.31), and 13% reduced risk after propensity score adjustment (HR 0.87, CI 95: 0.52-1.47). Statin use seemed not to have an effect on recurrence in patients with an unprovoked first event (multivariable HR 1.03, CI 95: 0.54-1.98), but the statistical power was low due to few events and the results must be interpreted with caution. In general, the risk estimates were slightly attenuated when prevalent users were included in the analyses. Conclusion: Our findings suggest that statins may have a modest decreasing effect on the risk of recurrent venous thrombosis. While we took care to minimize bias and confounding, the causality of the association is still unsettled.