Age at first venous thromboembolism and risk of recurrence: a prospective cohort study.

Risk of first venous thromboembolism (VTE) increases with age. We investigated whether age is related to the risk of recurrent VTE. We followed 694 patients for a mean of 40 months after first unprovoked proximal deep vein thrombosis (DVT) and/or pulmonary embolism (PE) and withdrawal of anticoagulants. We excluded patients with natural inhibitor deficiency, lupus anticoagulant, or cancer; patients who required indefinite anticoagulation; pregnant women; and women who had VTE related to female hormone use. The endpoint was symptomatic recurrent VTE.VTE recurred in 152 patients (22%). The adjusted hazard ratio (HR) of recurrence for a 10-year increase in age was 0.94 (95% confidence interval [CI], 0.82-1.08; p = 0.4). Compared with patients aged younger than 47 years (1st tercile of patient population) no significant increase in the risk of recurrent VTE was found among patients 47-61 years old (2nd tercile) or patients older than 61 years (3rd tercile) ([HR, 1.25; 95% CI, 0.78-2.01] and [HR, 0.93l; 95% CI, 0.56-1.53], respectively). Compared to patients older than 80 years, the HR of recurrence among patients younger than 50 years was 1.11 (95% CI, 0.11-10.3; p = 0.9). After 5 years, probability of recurrence was 32% (95% CI, 24%-40%) among patients aged less than 47 years; 21% (95% CI, 15%-28%) among patients 47-61 years old; and 33% (95% CI, 24%-42%) among patients older than 61 years (p = 0.5).Our results show that in patients with first unprovoked proximal DVT and/or PE, risk of recurrence is not related to age at first VTE. Regardless of age, these patients have a high risk of recurrence.