Neutrophil-Lymphocyte and Platelet-Lymphocyte Ratios as Predictors of Complicated Acute Appendicitis: A Retrospective Cohort Study

Background: Acute appendicitis (AA) is a frequent cause of acute abdominal pain in emergency departments. We aimed to evaluate the association and discriminatory performance of the neutrophil-lymphocyte ratio (NLR) and platelet-lymphocyte ratio (PLR) for identifying complicated acute appendicitis. Methodology: In this retrospective study, we analyzed 483 patients treated at the General Hospital of Carapicuiba from January 2018 to June 2024. Normality was assessed using the Shapiro-Wilk test, and bivariate comparisons were performed using the Mann-Whitney test. Multivariate logistic regression was used to investigate the association of complicated AA with NLR, PLR, age, and sex. A receiver operating characteristic (ROC) curve was constructed to determine sensitivity, specificity, and the area under the curve (AUC). Statistical significance was set at P < 0.05. Results: Of 483 patients, 273 (56.5%) had complicated appendicitis. Median NLR and PLR were higher in complicated versus uncomplicated cases (P < 0.001). The optimal ROC-derived cutoffs were NLR 8.84 (sensitivity 43.6%, specificity 79.5%; AUC 0.694; 95% confidence interval (CI), 0.645-0.742) and PLR 170.6 (sensitivity 40.7%, specificity 73.3%; AUC 0.600; 95% CI, 0.550-0.651). In unadjusted analysis, NLR >8.84 was associated with complicated appendicitis (odds ratio (OR) 3.00; 95% CI, 1.99-4.53). In the multivariable model including age and sex, PLR remained independently associated with complicated appendicitis. Conclusions: NLR and PLR were associated with complicated appendicitis in unadjusted analyses. After adjustment for age and sex, only PLR remained independently associated. Given their low cost and wide availability, these ratios may complement clinical assessment to support risk stratification and timely management, particularly in resource-limited settings.