PB1487 - Venous Thromboembolism and Major Bleeding Risk in Hospitalized Obese Patients Receiving Thromboprophylaxis with Enoxaparin

Background: Obese patients hospitalized for acute medical illness or surgery are at high risk of venous thromboembolism (VTE). The optimal dose and duration of thromboprophylaxis with low molecular weight heparin for these patients are uncertain. Most guidelines recommend weight adjusted doses.

Aims: To describe the rates and risk factors for VTE and major bleeding (MB) in a population of obese acutely ill medical or surgical patients receiving enoxaparin prophylaxis.

Methods: Patients with body mass index (BMI) >=30 Kg/m2 hospitalized between 2010 and 2019 who received thromboprophylaxis with enoxaparin were selected from the Optum database in the USA. Exclusion criteria were VTE, MB, or surgery in previous 90-days, and ongoing anticoagulant treatment or dual antiplatelet therapy. Event rates over a 90-day follow-up post enoxaparin initiation were estimated via the Kaplan-Meier (KM) method. Factors associated with outcome events were identified via Cox proportional hazard models. Included factors were those that were either statistically significant or deemed to be clinically relevant.

Results: A total of 46,382 and 13,333 patients met selection criteria for acute medical illness (median age 57, IQR 48-67) and surgery (median age 58, IQR 48-66), respectively. KM event rates at 90-days in medical patients were 2.4% for symptomatic VTE and 1.6% for MB; 3.6% and 2.9% in surgical patients, respectively (Table 1). The highest VTE rates were observed in patients hospitalized for thoracic surgery (10.0%) and cancer (4.7%). History of VTE was the strongest predictor of VTE in both groups (HR=8.98 [CI 7.80-10.35] for medical patients and HR=8.87 [CI 7.13-11.03] for surgery). History of MB was the strongest predictor of MB (HR=3.86 [3.22-4.61] in medical and HR=4.08 [3.19-5.20] in surgical patients) (Table 2).

Conclusion(s): The rates of symptomatic VTE are non-negligible in hospitalized obese patients receiving thromboprophylaxis with enoxaparin. Individual risk stratification is warranted to identify optimal doses and duration of pharmacologic prophylaxis.