Weighing the evidence: The obesity paradox and its impact on lower extremity bypass surgery outcomes

The obesity paradox, a reduced risk in overweight/obese patients but higher risk at body mass index extremes, has uncertain applicability for lower extremity bypass. We analyzed postoperative outcomes by body mass index category in patients undergoing lower extremity bypass.

We analyzed 67,842 lower extremity bypass patients using the TriNetX platform. Body mass index stratification included underweight, normal, overweight, and obesity class I-III. Each body mass index group was 1:1 propensity score matched to normal body mass index patients. Outcomes included mortality, major reintervention, major amputation, wound infection, nonhealing wounds, hemorrhage, and seroma.

Overweight, class I (odds ratio, 0.88; odds ratio, 0.84; P < .001) and II (odds ratio, 0.89; P = .014) patients had lower mortality risk at 30 days and 1 year. Class I and II (odds ratio, 0.87; odds ratio, 0.83; P < .001) patients had lower amputation risk. Underweight and class III patients had increased mortality (odds ratio, 1.21; P < .001; odds ratio, 1.18; P = .002), major reintervention (odds ratio, 1.13; P = .002; odds ratio, 1.19; P < .001), amputation (odds ratio, 1.19; P < .001; odds ratio, 1.14; P = .021), and hemorrhage/seroma (odds ratio, 1.21; P = .015; odds ratio, 1.27; P = .009). Wound complications rose with each body mass index class for class I-III (odds ratio, 1.31; odds ratio, 1.58, all P < .001).

The obesity paradox applies to mortality and amputation after lower extremity bypass. However, wound complication risk increased linearly with increased body mass index. This suggests that body mass index extreme patients warrant preoperative optimization while affirming the association of obesity and poor wound healing.