Diagnostic and Prognostic Accuracy of Interleukin-6 for Postoperative Infection in Abdominal Surgery in A Tertiary Care Center

Abstract Introduction: Sepsis is a significant postoperative risk in abdominal surgery, with traditional markers like WBC and CRP lacking specificity. Interleukin-6 (IL-6) is a promising biomarker, rapidly peaking after infection or injury and correlating with surgical stress and complications like sepsis and SIRS. Studies show IL-6 outperforms CRP and procalcitonin in early detection, particularly in open surgeries. Its diagnostic accuracy supports timely intervention, though further research is needed to optimize its clinical use. Methods: This single-center cohort study assessed postoperative complications after major abdominal surgery, excluding patients on preoperative antibiotics. Blood samples were collected at baseline and on postoperative days 1, 3, and 7. SIRS was diagnosed based on abnormal temperature, heart rate, respiratory rate, or leukocyte count. Outcomes included 30-day mortality, infections, sepsis, reoperations, and hospital stay duration. IL-6 levels were measured using ELISA, and clinical data on preoperative history, surgery details, and postoperative parameters were analyzed. Results: This study analyzed IL-6 as a biomarker for predicting complications in 75 patients after major abdominal surgery. IL-6 levels between 300-500 pg/mL were significantly associated with complications, with an optimal cut-off of 432 pg/mL. Fever (21.33%) and pneumonia (20%) were the most common complications, followed by SIRS, surgical site infections, anastomotic leaks, and mortality. · High IL-6 levels on day 1 were strongly associated with fever (p=0.0101), SIRS (p=0.0012), surgical site infections (p=0.0077), pneumonia (p=0.0189), and anastomotic leaks (p=0.0305). · Mortality and congestive heart failure showed no significant correlation with IL-6. · Day 1 IL-6 levels were more predictive of complications (p=0.0066) than day 3 levels (p=0.04566). Conclusion: Elevated IL-6 on day 1 is strongly associated with postoperative complications and provides better predictive accuracy than on day 3, making it a valuable marker for early clinical decisions.