Neutrophil-to-lymphocyte count ratio is associated with perforated appendicitis in elderly patients of emergency department

Purpose The diagnostic value of the neutrophil-to-lymphocyte count ratio (NLR) and the Appendicitis Inflammatory Response (AIR) score for identifying acute appendicitis (AA) perforation in elderly patients in the emergency department (ED) were evaluated. Methods A total of 103 patients who were admitted for appendectomy for AA via the ED between January 2012 and December 2014 were reviewed retrospectively. Patients aged 65 and over were included. Patient age, sex, comorbidities, body temperature, clinical findings and initial laboratory results including white blood cell (WBC) count, NLR, serum levels of CRP and total bilirubin (TB) in the ED were assessed, and the AIR score was calculated. Results Perforation due to AA was identified in 58 (56.3 %) elderly patients. Median WBC count, neutrophil count, CRP and TB were significantly higher in the perforated group compared to the non-perforated group (p = 0.005, p = 0.001, p = 0.004 and p = 0.012) in the ED. The NLR was significantly different in the two groups (perforated vs non-perforated group, 9.5 vs 5.1, p < 0.001). The area under the curve value of NLR was 0.755 (95 % CI 0.660-0.834), and the cutoff value was 5.6 (sensitivity 78.0 % and specificity 65.9 %). In multivariate logistic analysis, NLR > 5.6 [odds ratio (OR) 6.794, p = 0.001] was significant independent factor for AA perforation in elderly patients. The AIR score risk probability did not differ between the two groups of elderly patients (p = 0.094). Twenty-five (42.4 %) patients in the perforated group and five (11.4 %) patients in the non-perforated group were classified as high probability by the modified AIR score including the NLR value (p = 0.001). Conclusion We suggest that the initial NLR in the elderly patient is the most powerful predictive factor for the diagnosis of AA perforation in the ED.