Event rates and risk factors for venous thromboembolism and major bleeding in a population of hospitalized adult patients with acute medical illness receiving enoxaparin thromboprophylaxis

Background: We aimed to describe the event rates and risk-factors for symptomatic venous thromboembolism (VTE) and major bleeding in a population of hospitalized acutely ill medical patients. Methods: Patients ≥40 years old and hospitalized for acute medical illness who initiated enoxaparin prophylaxis were selected from the US Optum research database. Rates of symptomatic VTE and major bleeding at 90-days were estimated via the Kaplan-Meier (KM) method. Risk factors were identified via the Cox proportional hazards model. Results: A total of 123,022 patients met the selection criteria. The KM rates of VTE and major bleeding at 90-days were 3.5 % and 2.2 %, respectively. Among subgroups, the risk of VTE varied from 3.0 % in patients with ischemic stroke to 6.9 % in patients with a cancer-related hospitalization, and the risk of major bleeding varied from 1.9 % in patients with inflammatory conditions to 3.6 % in patients with ischemic stroke. Key risk factors for VTE were prior VTE (HR=4.15, 95 % confidence interval [CI] 3.80–4.53), cancer-related hospitalization (HR=2.35, 95 % CI 2.10–2.64), and thrombophilia (HR=1.64, 95 % CI 1.29–2.08). Key risk factors for major bleeding were history of major bleeding (HR=2.17, 95 % CI 1.72–2.74), history of non-major bleeding (HR=2.46, 95 % CI 2.24–2.70), and hospitalization for ischemic stroke (2.42, 95 % CI 2.11–2.78). Conclusion: There is substantial heterogeneity in the event rates for VTE and major bleeding in acute medically ill patients. History of VTE and cancer related hospitalization represent profiles with a high risk of VTE, where continued VTE prophylaxis may be warranted.