Objective: To determine the neutrophil/lymphocyte ratio as a predictor of severity in acute appendicitis. Methodology: An observational, cross-sectional, retrospective, and descriptive study was conducted on patients admitted for acute appendicitis to determine the predictive value of severity using the neutrophil-lymphocyte index (ratio of total neutrophils to total lymphocytes) with a cut-off point of 3. Other observed variables included sex, age, comorbidities, and surgical findings. The data were analyzed using descriptive statistics, diagnostic tests with a 95% confidence interval, and the SPSSv26.0 statistical package. Results: Sixty patients with a diagnosis of acute appendicitis were included, with an average age of 34.4 ± 14.2 years, 35 (58%) female, and an evolution of symptoms for 2.4 ± 2.1 days. Four (6.7%) had hypertension. No complications were observed in 30 cases (50%), while abscess and perforation occurred in 9 (15%). The predictive value of the neutrophil/lymphocyte index for the presence of severe complications showed a sensitivity of 100% (95% CI 84.5-100) and a negative predictive value of 100% (95% CI 67.6-100). Conclusion: The neutrophil/lymphocyte index has a sensitivity and negative predictive value of 100% for complicated acute appendicitis.
