Assessment of BMI and Venous Thromboembolism Rates in Patients on Standard Chemoprophylaxis Regimens After Undergoing Free Tissue Transfer to the Head and Neck

Abstract

ImportanceVenous thromboembolism (VTE) is a severe complication after free tissue transfer to the head and neck (H&N). Enoxaparin 30 mg twice daily (BID) is a common regimen for chemoprophylaxis. However, differences in enoxaparin metabolism based on body weight may influence its efficacy and safety profile.ObjectiveTo assess the association between BMI and postoperative VTE and hematoma rates in patients treated with prophylactic enoxaparin 30 mg BID.Design, Setting, and ParticipantsThis was a retrospective review of a prospectively collected cohort from 2012 to 2022. Postoperative VTE, hematoma, and free flap pedicle thrombosis were recorded within 30 days of index surgery. The setting was a tertiary academic referral center. Participants included patients undergoing H&N reconstruction with free flaps that received fixed-dose subcutaneous enoxaparin 30 mg BID postoperatively. Statistical analysis was conducted from April to May 2022.Main Outcomes and MeasuresOutcomes include incidence of VTE, hematoma, and flap pedicle thrombosis events within 30 days of the surgery. Univariate and multivariable regression models were used to evaluate associations between BMI and other patient factors with these outcomes.ResultsAmong the 765 patients included, 262 (34.24%) were female; mean (SD) age was 60.85 (12.64) years; and mean (SD) BMI was 26.36 (6.29). The rates of VTE and hematoma in the cohort were 3.92% (30 patients) and 5.09% (39 patients), respectively. After adjusting for patient factors, BMI was the only factor associated with VTE (OR, 1.07; 95% CI, 1.015-1.129). Obesity (BMI >30) was associated with increased odds of VTE (OR, 2.782; 95% CI, 1.197-6.564). Hematoma was not associated with BMI (OR, 0.988; 95% CI, 0.937-1.041). Caprini score of at least 9 was not associated with VTE (OR, 1.259; 95% CI, 0.428-3.701).Conclusions and RelevanceThis cohort study found that obesity was associated with an increased risk of VTE in patients after microvascular H&N reconstruction and while on standard postoperative chemoprophylaxis regimens. This association may suggest insufficient VTE prophylaxis in this group and a potential indication for weight-based dosing.

Venous Thromboembolism Rates After Free Flap Reconstruction of the Head and Neck Region

“…In our study, patients with a VTE event had significantly higher mean BMI values than patients who did not develop a postoperative VTE. This is consistent with our previous study, where BMI greater than 30 was identified as an independent risk factor for inadequate prophylaxis and increased VTE events 24 . In addition, in a previous prospective study, we found that BMI is a significant predictor of antifactor Xa levels after controlling for multiple variables 23 .…”

“…This is consistent with our previous study, where BMI greater than 30 was identified as an independent risk factor for inadequate prophylaxis and increased VTE events. 24 In addition, in a previous prospective study, we found that BMI is a significant predictor of antifactor Xa levels after controlling for multiple variables. 23 These findings relate to the changing strategy of VTE chemoprophylaxis by implementation of weight-based dosing protocols.…”

“…Previous studies from our institution focused on identification of the high-risk patients undergoing microvascular free flap reconstruction to optimize chemoprophylaxis regimens and improve postoperative outcomes by preventing both VTE and bleeding events. 23,24 This allowed us to critically assess our cohort to identify high-risk patients who are receiving insufficient VTE prophylaxis and change current protocols for potential implementation of personalized dosing. In the current study, we aimed to assess our entire institutional series of free flap reconstruction of the H&N region for the past 10 years to identify VTE and bleeding rates and the factors associated with VTE events.…”

Association between venous thromboembolism rates and different prophylactic anticoagulation regimens in patients undergoing free flap reconstruction of the head and neck region

“…Prior studies have estimated that every acute VTE event costs $12,000–15,0000 to treat, without counting the subsequent complications (Grosse et al, 2016; Veeranki et al, 2021). Patients undergoing microsurgical reconstruction of the head and neck (H&N) region are at increased risk of developing VTE due to the extended surgery time, malignancy itself, and immobilization after the surgery (Bahl et al, 2014; Chen et al, 2008; Eley et al, 2013; Garritano et al, 2013; Garritano & Andrews, 2016; Saadoun et al, 2021; 2022; Venkatesh et al, 2020).…”

“…In current clinical practice, peri‐ and post‐operative chemoprophylaxis (enoxaparin, heparin [UFH], or aspirin) has become the standard of care after major H&N surgery (C. J. Pannucci et al, 2011; Christopher J. Pannucci et al, 2021; Venkatesh et al, 2020). However, breakthrough VTE can occur even in the presence of chemoprophylaxis (Ong et al, 2017; Christopher J. Pannucci et al, 2021; Tipirneni et al, 2021; Venkatesh et al, 2020; Saadoun et al., 2022). In fact, VTE risk has been reported between 1.4% to 6% when patients received antithrombotic agents perioperatively (Bahl et al, 2014; Chen et al, 2008; Moreano et al, 1998; Ricci et al, 2016; Thai et al, 2013; Venkatesh et al, 2020).…”