Pan-Immune Inflammation Value (PIV) as A Predictor of Disease Severity in Adult Appendicitis: A Comparative Retrospective Study

Purpose The primary objective of this study is to evaluate the predictive value of pan-immune inflammation value (PIV) in determining the pathological severity in patients undergoing appendectomy for acute appendicitis. Secondary objective is to compare the predictive performance with other inflammatory markers such as neutrophil-to-lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR), systemic immune-inflammation index (SII) and systemic inflammation response index (SIRI). Methods This retrospective observational study included 2334 adult patients who underwent appendectomy between 2012 and 2024. Patients were classified into non-complicated (lymphoid hyperplasia, acute appendicitis) and complicated (phlegmonous, perforated, gangrenous appendicitis) groups based on postoperative histopathological findings. Preoperative hematological and biochemical data were collected to calculate inflammatory indices including NLR, PLR, SII, SIRI and PIV. Receiver Operating Characteristics (ROC) analysis and logistic regression were performed to evaluate diagnostic performance and independent predictors of complicated appendicitis. Results Of the 2334 patients, 1574 (67.4%) patients had non-complicated and 760 (32.6%) had complicated appendicitis. Neutrophil count had the highest AUC (0.655), followed by WBC (0.651), SIRI (0.631), NLR (0.619), and PIV (0.615). The optimal PIV cut-off of 643.2 showed a sensitivity of 70% and specificity of 48%. In multivariate logistic regression, PIV was significantly associated with complicated appendicitis (OR = 2.32; 95% CI: 1.72–3.16; p < 0.001). Conclusion PIV is a novel and independent marker with moderate predictive value for predicting pathological severity of acute appendicitis in adults. Clinical utility should be supported with prospective studies.