Having Class II/III Obesity Significantly Increases Risks of Wound Complications Following Lower Extremity Bypass by...

Although lower extremity bypass (LEB) may be the only viable option for limb salvage in selected patients with chronic limb threatening ischemia (CLTI), it carries significant postprocedural risks. Previous studies on the impact of body mass index (BMI) and LEB typically extrapolated data from national databases, which may be skewed by data abstracted from hospitals with vascular residency or fellowship training programs. The scarcity of data from non-teaching hospitals does not permit a comprehensive picture of outcomes.

We queried the Blue Cross Blue Shield Michigan Cardiovascular Consortium (BMC2) registry data to identify patients who underwent elective LEB. Cases with patients younger than 18 years old, in-hospital death, missing data, or emergent procedures, LEB for popliteal artery entrapment syndrome or trauma were excluded. Patient demographic characteristics are summarized into five BMI categories: underweight (BMI < 18.5), healthy weight (BMI≥18.5 & < 25), overweight (BMI ≥25 & < 30), Class I Obesity (BMI ≥ 30 & < 35) and Class II or III Obesity (BMI ≥ 35). Primary outcomes included 30-day and 1-year wound complications and amputation. Secondary outcomes included major adverse cardiac events (MACE) and their constituent elements (mortality, myocardial infarction (MI), stroke). Unadjusted differences were tested using F-tests from one-way ANOVAs, Kruskal-Wallis tests, or chi-square tests, depending on the variable type and distribution. These tests, when significant, were followed by Bayesian mixed effects logistic regression models to control for site, demographic and comorbidity differences between exposure groups. Bayesian models are interpreted as significant if the 95% credible intervals around the odds ratios do not include 1.00.

Between January 2016-December 2024, 7,676 patients underwent elective LEB, with a mean age of 67 years old. The study cohort was divided into five different BMI categories as follows: underweight (n=297, 3.9 %), healthy weight (n=2,325, 30.3%), overweight (n=2,639, 34.4 %), class I obesity (n=1,528, 19.9 %), class II or III obesity (n=887, 11.5 %). Using healthy weight patients as reference, adjusted analysis of primary outcomes demonstrated that class II/III obesity patients had significantly higher odds of 30-day and 1-year wound complications (30-day: odds ratio (OR), 1.728; 95% credible interval (CI), 1.31-2.279; 1-year: OR 1.881; 95% CI, 1.457-2.431). Interestingly, obese patients demonstrated lower odds of 1-year major amputations (class I obesity: OR, 0.74; 95% CI, 0.55-1.00; class II/III obesity: OR, 0.58; 95% CI, 0.39-0.86). For secondary outcomes, overweight and class I obesity patients had lower odds of 30-day mortality (overweight: OR 0.356; 95% CI, 0.167-0.725; class I obesity: OR 0.38; 95% CI, 0.147-0.829). Class I obesity patients also had lower odds of 1-year mortality (OR 0.727; 95% CI, 0.537-0.981). There were no differences in 30-day and 1-year MACE across all BMI cohorts.

The positive linear relationship between BMI and post-LEB wound complications may not preclude obese CLTI patients from elective LEB. Nevertheless, patients with higher BMI should be counseled on higher risks of wound complications after LEB.