The utility of the preoperative neutrophil-to-lymphocyte ratio in predicting severe cholecystitis: a retrospective cohort study

Background: To evaluate whether the neutrophil-to-lymphocyte ratio (NLR), as a prognostic indicator, in patients can differentiate between simple and severe cholecystitis. Methods: A database of 632 patients who underwent cholecystectomy due to cholecystitis during approximately a seven-year span in a single institution was evaluated. Severe cholecystitis was defined when the cholecystitis was complicated by secondary changes, including hemorrhage, gangrene, emphysema, and perforation. The NLR was calculated at admission as the absolute neutrophil count divided by the absolute lymphocyte count. We used receiver operating characteristic curve analysis to identify the optimal value for the NLR in relation to the severity of cholecystitis. Thereafter, the differences in clinical manifestations according to the NLR cut-off value were investigated. Results: Our study population comprised 503 patients with simple cholecystitis (79.6%) and 129 patients with severe cholecystitis (20.4%). The NLR of 3.0 could predict severe cholecystitis with 70.5% sensitivity and 70.0% specificity. A higher NLR (>= 3.0) was significantly associated with older age (p = 0.001), male gender (p = 0.001), admission via the emergency department (p < 0.001), longer operation time (p < 0.001), higher incidence of postoperative complications (p = 0.056), and prolonged length of hospital stay (LOS) (p < 0.001). Multivariate analysis found that patient age >= 50 years (odds ratio [OR]: 2.312, 95% confidence interval [CI]: 1.472-3.630, p < 0.001), preoperative NLR >= 3.0 (OR: 1.876, 95% CI: 1.246-2.825, p = 0.003), and admission via the emergency department (OR: 1.764, 95% CI: 1.170-2.660, p = 0.007) were independent factors associated with prolonged LOS. Conclusions: NLR = 3.0 was significantly associated with severe cholecystitis and prolonged LOS in patients undergoing cholecystectomy. Therefore, preoperative NLR in patients undergoing cholecystits due to cholecystitis seemed to be a useful surrogate marker for severe cholecystitis.