Influence of baseline anemia on long-term clinical outcomes in patients with venous thromboembolism: from the COMMAND VTE registry

The influence of anemia on the long-term clinical outcomes has not been fully evaluated in patients with venous thromboembolism (VTE). We evaluated the influence of anemia among 3012 patients in the COMMAND VTE Registry with a median follow-up period of 1219 days. The outcomes measures were ISTH major bleeding, recurrent VTE and all-cause death. There were 1012 patients (34%) with moderate/severe anemia (Hb ≤ 10.9 g/dl), 615 patients (20%) with mild anemia (Hb 11.0–12.9 g/dl for men, and 11.0–11.9 g/dl for women), and 1385 patients (46%) without anemia. The cumulative 5-year incidence of major bleeding was significantly higher in patients with anemia (moderate/severe anemia: 17.6%, mild anemia: 12.1%, and no anemia: 8.7%, P < 0.001). After adjusting the confounders, the excess risk of mild and moderate/severe anemia, respectively, relative to no anemia for major bleeding remained significant (mild: adjusted HR 1.41: [95% CI 1.00–1.98], P = 0.048; moderate/severe: adjusted HR 1.91: [95% CI 1.42–2.58], P < 0.001, respectively). The excess risk of moderate/severe anemia relative to no anemia was also significant for mortality (adjusted HR 2.89: 95% CI 2.45–3.42, P < 0.001), but the risk was neutral for recurrent VTE (adjusted HR 1.05: 95% CI 0.76–1.45, P = 0.77). In conclusions, VTE patients with mild and moderate/severe anemia had higher risk for major bleeding events without significant excess risk for recurrent VTE events, and the risk for major bleeding events increased according to the severity of anemia. We should pay more attention to the optimal intensity and duration of anticoagulation in VTE patients with anemia.