How to Manage Thromboprophylaxis in Obese and Extremely Obese Patients?

Introduction

Venous thromboembolism (VTE) is the most common complication in extremely obese individuals within the first 30 days post-bariatric surgery. Therefore, it is crucial to optimally set thromboprophylaxis, i.e., to optimize the dose of low molecular weight heparin (LMWH). Essentially, one can choose fixed doses of LMWH or attempt to set the optimal dose by measuring anti-Xa activity.

Study Objectives and Course

A study, whose results were recently published in the journal Obesity Surgery, evaluated the effectiveness of pre-specified doses of enoxaparin in thromboprophylaxis for patients undergoing bariatric surgery. It assessed the proportion of patients who, upon subsequent determination of anti-Xa activity, achieved target values in the range of 0.2−0.4 IU/ml. The authors also focused on which biometric or laboratory parameters predicted (non-)achievement of target anti-Xa activity.

It was a prospective study of 236 patients. They were divided into two groups based on body weight (Group 1: < 150 kg; Group 2: ≥ 150 kg). Enoxaparin was administered 2× daily, with the dose depending on initial weight (Group 1: 2× 40 mg/day; Group 2: 2× 60 mg/day). In both groups, anti-Xa activity was measured on the 3rd day of starting thromboprophylaxis.

Results

In Group 1, with an average weight of 121.7 ± 17.49 kg and BMI of 42.94 ± 6.84 kg/m², 57.25% of patients achieved the target anti-Xa activity range.

In Group 2, with an average weight of 191.66 ± 33.37 kg and BMI of 63.21 ± 10.05 kg/m², 60.71% of patients reached the target anti-Xa activity range.

Multiple regression analysis showed that weight, waist-to-hip ratio, glomerular filtration, creatinine levels, and glycated hemoglobin (HbA_1c) values were significantly related to anti-Xa activity values, but only in patients in Group 1.

No VTE or perioperative bleeding was reported within 3 months post-procedure.

Conclusion

Determining anti-Xa activity helps provide a better understanding of the real effectiveness of thromboprophylaxis in obese patients, particularly those with a high degree of obesity reaching a body weight of ≥ 150 kg. In routine clinical practice, this simple test should be considered for all patients at risk of VTE requiring thromboprophylaxis.

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Source: Stier C., Koschker A. C., Stier R. et al. Are we missing treatment standards for thromboprophylaxis of the obese and super-obese patient population? A prospective systematic cohort study. Obes Surg 2020 Jan 23, doi: 10.1007/s11695-020-04383-w [Epub ahead of print].