Venous Thromboembolism Prophylaxis in Obese Medical Patients: a Retrospective Cohort Study

Abstract

Background: The incidence of obesity has increased 3 fold in Canada between 1985 and 2011. Obese patients are 2-3 times more likely to develop venous thromboembolism (VTE), and over 60% of VTE occurs in hospital. There is very little literature on VTE prophylaxis in the obese medical patient. Objective(s): Our primary objective was to identify the incidence of objectively documented symptomatic VTE during hospitalization or up to ninety days post discharge. Our secondary objectives were to describe the prescribing patterns of VTE prophylaxis received in hospitalized obese medical patients (body mass index [BMI] ≥ 30 kg/m2) as well as risk factors for VTE in obese patients. Methods: A retrospective design was used look at obese patients admitted to a general medicine service at three tertiary care academic teaching hospitals in Calgary, AB, Canada from January 1, 2012 to December 31, 2012. VTE was identified based on clinical diagnosis and incidence was calculated. Results: There were 443 patients included in the analysis. The average age and BMI were 58.5 years and 41 kg/m2 respectively, and 70.2% were males. The median length of stay in hospital was 7 days (IQR 4-13). A total of 122 patients (27.5%) of patients did not receive thromboprophylaxis during their hospitalization. Unfractionated heparin (UFH) was the most common agent prescribed (37.9%), and only seven patients received high-dose thromboprophylaxis. The median duration of prophylaxis was 6.5 days (IQR 4-12). Seven patients (1.6%) developed VTE (5 pulmonary embolism and 2 DVT) during the study period, and six of these patients received thromboprophylaxis. In terms of risk for VTE, the median Padua Prediction Score for the study group was 2 (IQR 1-3). Conclusion: There is very little literature on VTE prophylaxis and incidence of VTE in the obese medical patient. Given the low risk for and incidence of VTE in this study, particularly in the context of 27.5% of the study population not receiving thromboprophylaxis, there is a need for further research to evaluate the efficacy and safety of high dose thromboprophylaxis in the obese medical patient.