Lower Visceral Adipose Radiodensity Is Associated With Greater Early Postoperative Inflammation After Colon Surgery

Background Early postoperative systemic inflammation varies among patients undergoing colon surgery and is not fully explained by operative factors. Visceral and subcutaneous fat may contribute to this variability. Computed tomography-derived adipose radiodensity provides an imaging marker of adipose tissue quality. We evaluated whether adipose radiodensity was associated with the postoperative inflammatory response. Methods In this retrospective cohort study, 202 adults with preoperative CT imaging were analyzed. Visceral and subcutaneous adipose radiodensity (VFHu and SFHu) were quantified at the L3 level. Multivariable linear regression evaluated associations with postoperative day 1 systemic inflammatory response index (POD1 SIRI), incorporating prespecified interactions with baseline inflammation, hemoglobin A1C, and surgical urgency. Results Neither VFHu nor SFHu was independently associated with preoperative inflammation. In emergency surgery, lower VFHu was strongly associated with higher POD1 SIRI (standardized β for higher VFHu=−0.683; P < 0.0001). This association was largely absent in elective surgery. Baseline inflammation, A1C, and SFHu modified these relationships: higher Pre-SIRI carried forward more strongly at higher VFHu (P = 0.001), the low-VFHu association was weaker at higher A1C (P = 0.004), and higher SFHu reduced the Pre-SIRI–POD1 SIRI increase (P = 0.010). Conclusions CT-derived adipose radiodensity was associated with variability in POD1 inflammation after colon surgery, particularly in emergency cases. These findings suggest that visceral and subcutaneous fat compartments may shape the postoperative inflammatory response differently. Adipose-related differences may help explain why some patients develop greater systemic inflammation than expected after similar operations. Synopsis Lower visceral adipose radiodensity, higher baseline inflammation, and emergency surgery were associated with higher POD1 SIRI. Prespecified interactions showed that these associations varied with glycemic burden, surgical urgency, and adipose compartment, consistent with biologic heterogeneity in the postoperative inflammatory response.