The long-term recurrence risk of patients with unprovoked venous thromboembolism: an observational cohort study

Background: The long-term recurrence risk (ltRR) of venous thromboembolism (VTE) is uncertain. Objective: To assess the ltRR of patients with first unprovoked VTE. Patients/methods: Patients were classified into three categories: distal deep vein thrombosis (DVT), proximal DVT or pulmonary embolism (PE), that is, PE associated with DVT or isolated PE. Patients with major thrombophilia or antithrombotic therapy were excluded. The endpoint was recurrent symptomatic VTE. Results: A total of 839 patients were followed for a median of 7.7 years. VTE recurred in 263 patients (31%). After 10 and 20 years, the cumulative ltRR was 32% (95% confidence interval [CI], 29-36) and 44% (95% CI, 38-49) with 3.9 (95% CI, 3.3-4.6) and 3.3 (95% CI, 2.74.0) events per 100 patient-years, respectively. The adjusted hazard ratio was 2.1 (95% CI, 1.4-3.2) and 2.1 (95% CI, 1.4-3.2) for patients with proximal DVT or PE compared with patients with distal DVT and was 2.1 (95% CI, 1.6-2.9) for men compared with women. At 10 years, 4.7 (95% CI, 3.8-5.8) events per 100 patient-years occurred in men with proximal DVT or PE, 2.4 (95% CI, 1.2-4.4) in men with distal DVT, 1.9 (95% CI, 1.2-2.8) in women with proximal DVT or PE and 0.9 (95% CI, 0.2-1.9) in women with distal DVT. Conclusion: The ltRR of patients with first unprovoked VTE is high and dependent upon sex and VTE site.