Delta neutrophil index as an early predictor of acute appendicitis and acute complicated appendicitis in adults

BACKGROUND This retrospective study aimed to evaluate the ability of the delta neutrophil index (DNI) to predict histologically normal appendicitis preoperatively and to differentiate between simple and complicated appendicitis. METHODS The data from 650 patients were divided into positive and negative appendectomy groups (histologically normal appendicitis). The patients in the acute appendicitis group were further sub-divided into simple and complicated appendicitis groups. RESULTS The DNI was significantly higher in the positive group than in the negative appendectomy group (0.4 vs. -0.4, p < 0.001) as well as in the complicated group compared with that in the simple appendicitis group (1.2 vs. 0.3, p < 0.001). The DNI independently predicted a positive appendectomy and an acute complicated appendicitis in multivariate logistic regression analysis [odds ratio (OR) 2.62, 95% confidence interval (CI) (1.11~6.16), p = 0.028 and odds ratio (OR) 4.10, 95% confidence interval (CI) (2.94~5.80), p < 0.001]. The optimum cut-off for a positive appendectomy and acute complicated appendicitis were 0.2 [area under curve (AUC) 0.709] and 0.6 (AUC 0.727). CONCLUSIONS We suggest that obtaining a preoperative DNI is a useful parameter to aid in the diagnosis of histologically normal appendicitis and to differentiate between simple and complicated appendicitis.