Risk Factors for Venous Thromboembolism in Hospitalized Patients With Acute Medical Illness: Analysis of the MEDENOX Study

BACKGROUND: There is limited information about risk factors for venous thromboembolism (VTE) in acutely ill hospitalized general medical patients. METHODS: An international, randomized, double-masked, placebo-controlled trial (MEDENOX) has previously been conducted in 1102 acutely ill, immobilized general medical patients and has shown the efficacy of using a low-molecular-weight heparin, enoxaparin sodium, in preventing thrombosis. We performed logistic regression analysis to evaluate the independent nature of different types of acute medical illness (heart failure, respiratory failure, infection, rheumatic disorder, and inflammatory bowel disease) and predefined factors (chronic heart and respiratory failure, age, previous VTE, and cancer) as risk factors for VTE. RESULTS: The primary univariate analysis showed that the presence of an acute infectious disease, age older than 75 years, cancer, and a history of VTE were statistically significantly associated with an increased VTE risk. Multiple logistic regression analysis indicated that these factors were independently associated with VTE. CONCLUSIONS: Several independent risk factors for VTE were identified. These findings allow recognition of individuals at increased risk of VTE and will contribute to the formulation of an evidence-based risk assessment model for thromboprophylaxis in hospitalized general medical patients.