Glucocorticoid use and risk of first and recurrent venous thromboembolism: self-controlled case-series and cohort study.

Glucocorticoid treatment increases venous thromboembolism (VTE) risk. Whether this is due to the medication or the underlying disease, or affects the risk of VTE recurrence, has been difficult to determine. The aim of our present study was to quantify the risk for first and recurrent VTE associated with oral glucocorticoids use, considering the underlying disease. A total of 2547 patients with VTE from the Multiple Environmental and Genetic Assessment of Risk Factors for Venous Thrombosis (MEGA) study were linked to the Dutch Pharmaceutical Statistics register. The risk of first VTE during periods of exposure with oral glucocorticoids was estimated by the self-controlled case series method and that of recurrent VTE was examined in a cohort design. The incidence rate ratio (IRR) of first VTE in the period of glucocorticoid treatment was 3·51 [95% confidence interval (CI) 2·55-4·80]. This IRR was 2·53 (95% CI 1·10-5·72) in the week before treatment started, 5·28 (95% CI 2·89-9·53) in the first 7 days of treatment, remained elevated afterwards and decreased to 1·55 (95% CI 0·85-3·12) after 6 months, as compared to unexposed periods. The hazard ratio for recurrence was 2·72 (95% CI 1·64-4·78) in treatment periods as compared with no treatment. The increased risk of VTE associated with oral glucocorticoid treatment is due to a combined effect of the treatment and the underlying disease, remaining high during the first months of prescription.