Neutrophil-to-lymphocyte ratio in the diagnosis of acute appendicitis. Assessment of its diagnostic accuracy.

INTRODUCTION: Acute appendicitis (AA) in pediatric patients requires an accurate diagnosis. The neutrophil-to-lymphocyte ratio (NLR) is an accessible parameter useful for its diagnosis.

OBJECTIVE: To determine NLR accuracy to diagnose AA in patients with abdominal pain.

POPULATION AND METHODS: Diagnostic test study. A total of 520 patients seen at the Pediatric Emergency Department were included. Diagnostic accuracy was estimated based on sensitivity, specificity, predictive values, and likelihood ratios. A multiple logistic regression model was used to assess the effect of potentially confounding variables in the relationship between NLR and AA.

RESULTS: The prevalence of AA was 49%. For a cutoff point of 5, sensitivity was 85.1%, specificity: 78.9%; positive predictive value: 79.5%; and negative predictive value: 84.6%. However, based on likelihood ratios, the NLR is not powerful enough to diagnose AA (positive likelihood ratio = 4.03 and negative likelihood ratio = 0.18) and did not exhibit diagnostic usefulness in complicated appendicitis (positive likelihood ratio = 1.57 and negative likelihood ratio = 0.55). Following adjustment for age, sex, obesity, time since symptom onset, and analgesic use, the NLR was an explanatory variable for the presence of AA (odds ratio = 23.53; 95% confidence interval: 13.14-42.15).

CONCLUSIONS: The NLR alone is not sufficiently accurate to confirm or rule out the presence of AA. However, the NLR can be used together with other tests to select patients in whom further study is necessary.