Abstract 11662: Obesity Does Not Increase Venous Thromboembolism in Hospitalized Medical Patients Upon Multivariate Analysis

Abstract

Introduction: Obesity increases the risk of venous thromboembolism (VTE) in hospitalized medical patients. Standard chemoprophylaxis in these patients may be suboptimal, potentially leading to increased VTE. The objective of this study was to compare the rate of VTE in obese (body mass index [BMI] ≤30 kg/m 2 ) medical patients receiving standard VTE prophylaxis with rates in non-obese patients (BMI 17-29.9 kg/m 2 ). Hypothesis: Obese patients will suffer from a higher incidence of VTE within 90 days of hospitalization. Methods: In a single-center retrospective cohort study, patients admitted to all medical units between November 2007 and November 2013 were evaluated for eligibility if they received an initial dose of VTE prophylaxis within 48 hours of admission. Appropriate prophylaxis was heparin 5000 units subcutaneously (SQ) every 8 to 12 hours or enoxaparin 30 mg SQ twice daily or 40 mg SQ once daily. Exclusion criteria included hypercoagulable states, therapeutic anticoagulation, and admission for trauma or surgery. The primary outcome was 90 day VTE defined as deep vein thrombosis or pulmonary embolism using ICD-9 codes. Secondary outcomes included in-hospital VTE, 30 day VTE, and 90 day mortality. Univariate and multivariate analyses were used in calculating p-values and odds ratios (OR) for the primary outcome. Results: There were 17,525 patients eligible for inclusion. The final cohort included 4,237 obese patients and 4,990 non-obese patients (median BMI 36 and 25 kg/m 2 , respectively). Obesity increased the risk of in-hospital VTE (5.6% vs. 4.4%; p=0.01), 30 day VTE (5.7% vs. 4.6%; p=0.013), and 90 day VTE (5.9% vs. 4.8%; p=0.028) on univariate analysis. However, using multiple logistic regression, obesity was not an independent predictor of 90 day VTE (OR 1.0; p=0.83). Variables which independently increased 90 day VTE were Charlson Comorbidity Index (OR 1.09; p=0.003), prior VTE (OR 36.35; p<0.001), congestive heart failure (OR 1.33; p=0.017), and surgery in 90 days following admission (OR 1.56; p=0.004). Mortality was lower at 90 days in obese patients (3.3% vs. 6.3% non-obese; p<0.001) Conclusions: The incidence of VTE at 90 days in hospitalized medical patients is significant, but it is uncertain if obesity independently contributes to this.