Objective: To determine the neutrophil/lymphocyte ratio compared to serum bilirubin levels as a predictor of severity in acute appendicitis. Methodology: An observational, cross-sectional, retrospective, and descriptive study was conducted in patients admitted for acute appendicitis to compare the positive predictive value of complicated acute appendicitis using the neutrophil-lymphocyte index, with a cutoff point of 3, compared to total serum bilirubin levels with a cutoff point greater than 1.0 mg/dl. It was analyzed with descriptive statistics, diagnostic tests with a 95% confidence interval, and using the SPSSv26.0 statistical package. Results: There were 60 patients diagnosed with acute appendicitis, with an average age of 34.4 ± 14.2 years, 35 (58%) were female, with an average evolution time of 2.4 ± 2.1 days, and 4 (6.7%) were hypertensive. No complications were observed in 30 cases (50%), abscess, and perforation in 9 cases (15%), with perforation only occurring at the same frequency. The positive predictive value of the neutrophil/lymphocyte index for the presence of severe complications showed a sensitivity of 100%, while total bilirubin showed 55%; the negative predictive value of the neutrophil/lymphocyte index was 100%, and total bilirubin was 40.6%. ROC curve with IN/L at 0.46 and total bilirubin at 0.36. Conclusion: The neutrophil/lymphocyte ratio has higher sensitivity and negative predictive value for complicated acute appendicitis than the level of serum bilirubin.
