Having class II/III obesity significantly increases risks of wound complications following lower extremity bypass by twofold.

OBJECTIVE

Although lower extremity bypass (LEB) may be the only viable option for limb salvage in selected patients with chronic limb-threatening ischemia, 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 nonteaching hospitals does not permit a comprehensive picture of outcomes.

METHODS

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, in-hospital death, missing data, emergent procedures, or LEB for popliteal artery entrapment syndrome or trauma were excluded. Patient demographic characteristics are classified into five BMI categories: underweight (BMI < 18.5), healthy weight (BMI ≥ 18.5 and <25), overweight (BMI ≥ 25 and <30), class I obesity (BMI ≥ 30 and <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 and their constituent elements (mortality, myocardial infarction, and stroke). Unadjusted differences were tested using F-tests from one-way analyses of variance, Kruskal-Wallis tests, or χ2 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 (CIs) around the odds ratios (ORs) do not include 1.00.

RESULTS

Between January 2016 and December 2024, a total of 7676 patients underwent elective LEB, with a mean age of 67 years. The study cohort was divided into five different BMI categories as follows: underweight (n = 297; 3.9%), healthy weight (n = 2325; 30.3%), overweight (n = 2639; 34.4%), class I obesity (n = 1528; 19.9%), class II or III obesity (n = 887; 11.5%). Using healthy weight patients as reference, adjusted analysis of primary outcomes demonstrated that patients with class II/III obesity had significantly higher odds of 30-day and 1-year wound complications (30-day: OR, 1.728; 95% 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, patients with overweight and class I obesity 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). Patients with class I obesity 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 major adverse cardiac events across all BMI cohorts.

CONCLUSIONS

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