Impact of Reduced Enoxaparin Prophylactic Dosing on Bleeding and Thrombotic Risk for Low Body Weight Post-Operative Colorectal Surgery Patients.

Colorectal surgery (CORS) patients are at the highest risk of any general surgery population for the development of post-operative venous thromboembolism (VTE) and are also at an increased risk for post-operative bleeding, especially with procedures related to early cancer stages. Low molecular weight heparin (LMWH) is recommended for VTE prophylaxis in this surgical population. Current guidelines and primary literature along with institutional protocols support dosage adjustments for obesity and impaired renal function, but literature providing optimal VTE prophylactic LMWH dosing is extremely limited for underweight, surgical patients. The aim of this study was to evaluate both bleeding and VTE rates for hospitalized underweight colorectal surgery patients receiving post-operative VTE prophylaxis with standard enoxaparin 40 mg subcutaneously (SQ) every 24 hours versus reduced dose enoxaparin 30 mg SQ every 24 hours. This trial was a multicenter, retrospective chart review with data collected on post-operative CORS patients over a 10-year period. Patients were included if aged 18 years and older, weighed less than 50 kg, and received at least 1 dose of enoxaparin 40 mg or 30 mg post-operatively. The primary endpoint was a descriptive comparison of post-operative bleeding with use of standard enoxaparin 40 mg SQ every 24 hours compared to reduced dose enoxaparin 30 mg SQ every 24 hours for post-operative VTE prophylaxis. The secondary endpoint was the descriptive comparison of post-operative thrombotic event rates in the same population. The total population investigated included 146 patients. One hundred twenty-nine (88.4%) received standard enoxaparin and 17 (11.6%) received reduced enoxaparin. Overall, 9 bleeding events (7.0%) and 2 major VTE events (1.6%) occurred, all within the standard enoxaparin group. Standard dose enoxaparin for post-operative VTE prophylaxis demonstrated increased bleeding and thrombotic events requiring medical and surgical intervention in comparison to reduced dose enoxaparin for low body weight CORS patients. The results of this study are hypothesis generating and continued research involving more robust systematic reviews are needed to evaluate both safety and efficacy of reduced VTE prophylaxis with LMWH in the underweight, surgical patient population.