Hemogram-derived Ratios in the Prognosis of Acute Appendicitis

BACKGROUND AND AIMS: Early identification by gastroenterologists of peritonitis in acute appendicitis may support timely decision-making when clinical assessment and imaging are equivocal. The aim of this study was to assess the diagnostic and predictive value of routinely available laboratory parameters and systemic inflammatory indices in identifying peritonitis among patients undergoing surgery for acute appendicitis. By integrating clinical features, biochemical markers and composite hematological ratios, this study seeks to contribute to improved risk stratification and early decision-making in patients with acute appendicitis. METHODS: We conducted a single-center retrospective observational study of adults (≥18 years) undergoing appendectomy for acute appendicitis (July 2023-July 2024). Patients were stratified by intraoperatively confirmed peritonitis. Admission biomarkers and complete hemogram-derived indices were evaluated using ROC analysis (AUC; Youden cut-offs). Multivariable logistic regression models were adjusted for age, gender, time from symptom onset to surgery, and Alvarado score. RESULTS: Among the 99 patients included, 52 (52.5%) had peritonitis. Compared with patients without peritonitis, those with peritonitis had a higher median age, body mass index (BMI), Alvarado score, and C-reactive protein (CRP) level. CRP showed the highest discriminatory ability for identifying peritonitis (AUC=0.713, 95%CI: 0.613-0.813), with a cut-off value of 15.1 mg/L, corresponding to a sensitivity of 70.6% and a specificity of 70%. Hemogram-derived inflammatory indices demonstrated moderate discriminatory performance for predicting peritonitis, including the monocyte-to-lymphocyte ratio (MLR; AUC=0.680; cut-off ≥0.653), eosinophil count (AUC=0.663; cut-off 0.035×10⁹/L) for predicting the absence of peritonitis, the systemic inflammation response index (SIRI; AUC=0.657; cut-off ≥7.42), and the neutrophil-to-lymphocyte ratio (NLR; AUC=0.647; cut-off ≥10.855). In adjusted models, MLR ≥0.653 (aOR=6.92, 95%CI: 2.55-21.21), SIRI ≥7.42 (aOR=6.89, 95%CI: 2.46-22.29), and NLR ≥10.855 (aOR=5.88, 95%CI: 2.16-18.13) were associated with increased odds of peritonitis, whereas eosinophil count ≥0.035×10⁹/L was inversely associated with peritonitis (aOR=0.22, 95%CI: 0.08-0.54). CONCLUSIONS: Hemogram-derived inflammation indices, particularly MLR, SIRI, and NLR, are independently associated with intraoperative peritonitis and may complement CRP for preoperative risk stratification. Prospective multicenter validation is warranted to confirm thresholds and clinical utility.