Background

Venous thromboembolism (VTE) events remain a top cause of morbidity and mortality following bariatric surgery. Thus, prophylactic BMI-tiered low-molecular-weight heparin (LMWH) regimens have been implemented. The adequacy of such prophylaxis has been questioned. Objective: The aim of this study is to evaluate the adequacy of BMI-based VTE prophylaxis using the anti-factor Xa (anti-Xa) assay in patients with obesity undergoing bariatric surgery.

Methods

This is a retrospective review of adult patients undergoing Roux-en-y gastric bypass (RNYGB), laparoscopic sleeve gastrectomy (LSG), or revisional bariatric procedures, at a high-volume, community-based institution, between January 2017 and December 2020. Patients received twice daily, BMI-tiered dosing of LMWH post-operatively. Individuals with BMI <50 kg/m2 received 40 mg LMWH; those with BMI >50 kg/m2 received 60 mg LMWH. Anti-Xa levels were analyzed 4-6 hours following the second or subsequent dose. Levels of 0.2-0.4 IU/mL were considered prophylactic.

Results

A total of 203 patients (76% female) were included. Median age and BMI were 46 years and 50.79 kg/m2, respectively. Seventy-two percent of patients underwent RNYGB. Ultimately, 37.4% of patients did not achieve adequate prophylaxis; 23% were supra-prophylactic. Ninety patients had BMI <50. Of these, 17 were supra-prophylactic and 16 sub-prophylactic. One hundred-thirteen patients had BMI >50. Of these, 29 were supra-prophylactic and 14 sub-prophylactic. Adequacy of dosing did not differ significantly based on patient demographics.

Conclusions

BMI-tiered LMWH dosing for VTE prophylaxis in the bariatric surgery population is inadequate in achieving prophylaxis in greater than 37% of patients. This is substantially different than previously reported data.