Comparison of Anti-factor Xa Levels in Female and Male Patients with Obesity After Enoxaparin Application for Thromboprophylaxis

Abstract

Purpose Venous thromboembolic events (VTEs) are common complications after bariatric surgery, and enoxaparin is commonly used to prevent VTEs. The risk for VTEs is sex-specific. Whether enoxaparin application results in similar anti-factor Xa activities (aFXa) in males and females with obesity remains to be determined. We investigated whether our dosage regimen of enoxaparin resulted in similar serum aFXa levels in female and male patients undergoing bariatric surgery. Materials and Methods We administered enoxaparin twice daily in patients undergoing bariatric surgery. Patients with a body mass index (BMI) > 60 kg/m2 (n = 11) received 60 mg enoxaparin (group 2), and patients with lower BMI (n = 86) received 40 mg per dose (group 1). Peak aFXa levels were measured 3 days after surgery. The primary outcome was the aFXa level. As a secondary outcome, we detected VTEs and major bleeding events and explored the possible influencing factors of aFXa. Results Women had higher aFXa than men, but after matching for anthropometric values, the two groups were similar (females: 0.17 ± 0.08 U/ml; males: 0.18 ± 0.08 U/ml). Linear regression revealed a moderate relationship between weight and aFXa levels. The 3-month follow-up was attended by 94.9%, at which one patient had pulmonary embolism. Conclusion Individual enoxaparin dosage regimens for men and women do not seem to be required. Weight-based dosing regimen seems to be a more reasonable choice. Graphical abstract

Weight-adjusted dosing of tinzaparin for thromboprophylaxis in obese medical patients

“…Most data exist only on the use of enoxaparin for thromboprophylaxis in bariatric surgery. These studies conclude that patients receiving a weight-based enoxaparin prophylaxis are more likely to have their anti-Xa activity in the target range than with a fixed-dose regimen, whereas thrombotic complications are rare [ [29] , [30] , [31] , [32] , [33] , [34] ].…”

Strategies involving low-molecular-weight heparin for the treatment and prevention of venous thromboembolism in patients with obesity: A systematic review and meta-analysis

“…The secondary outcomes were the incidence of supraprophylactic (supratherapeutic) anti-Xa levels and subprophylactic (subtherapeutic) anti-Xa levels. Although currently controversial ( 12 , 17 , 18 ), the prophylactic and therapeutic levels of anti-Xa are 0.2-0.4 IU/ml and 0.5-1.0 IU/ml, respectively.…”

“…Recent research shows that the use of a standard dosage of LMWH for prevention in this specific weight group may be inadequate (11)(12)(13). In a large-scale retrospective cohort study, despite receiving chemoprophylaxis, critically ill obese patients had a significantly higher incidence of VTE than nonobese patients (3).…”

European guidelines on peri-operative venous thromboembolism prophylaxis: first update.

“…In bariatric surgery, some studies have shown that LMWH at doses higher than standard-dose used in nonobese patients (fixed, adjusted to weight, or to BMI) achieve expected peak anti-Xa levels (between 0.2 and 0.5 IU ml −1 ) more frequently 15–22 . However, the evidence regarding the anti-Xa effect of higher doses of LMWH and heparin on VTE is uncertain 23,24 …”

“…5,14 In bariatric surgery, some studies have shown that LMWH at doses higher than standard-dose used in nonobese patients (fixed, adjusted to weight, or to BMI) achieve expected peak anti-Xa levels (between 0.2 and 0.5 IU ml À1 ) more frequently. [15][16][17][18][19][20][21][22] However, the evidence regarding the anti-Xa effect of higher doses of LMWH and heparin on VTE is uncertain. 23,24 Although one study has reported a lower incidence of VTE starting LMWH 12 h before laparoscopic bariatric surgery, compared to starting postoperatively, 25 the evidence on the effect of prophylaxis timing is uncertain.…”