Men had a higher risk of recurrent venous thromboembolism than women: a large population study

Background: Most reports of sex differences in the risk of recurrent venous thromboembolism (VTE) are based on small or moderate sized cohorts of selected patients with VTE.

Methods: We aimed to determine the effect of sex on recurrent VTE in a large non-selected, real-world population of men and women with incident VTE. Using the linked administrative health care databases of the province of Québec, Canada, we constructed a cohort of patients with a first-time diagnosis of VTE between January 1, 1996 and December 31, 2004. Patients were followed forward in time for the occurrence of recurrent VTE until the earliest of either death, termination of health coverage, or end of study period (December 31, 2005). The cohort comprised 55,314 patients (43% men and 57% women) with incident VTE and the mean age was 61.9 years.

Results: During a mean follow-up of 3.9 years, 5243 (9.5%) of patients developed recurrent VTE. Men had a significantly higher rate of recurrence than women (adjusted hazard ratio = 1.13; 95% CI, 1.07-1.19), and this difference persisted when women with hormonally mediated VTE were excluded from the analysis (adjusted hazard ratio = 1.15; 95% CI, 1.08-1.21). At 5 years, the cumulative probability of recurrent VTE was 12.4% among men versus 10.9% among women (P = 0.0001).

Conclusions: Our study is the largest to date to report an effect of sex on risk of VTE recurrence, with men having about a 13% higher risk of recurrence than women. This provides further evidence that sex is a significant predictor of VTE recurrence.