Objective To explore the value of systemic immune-inflammation index (SII) in differentiating acute and chronic cholecystitis.

Methods A total of 297 patients with cholecystitis who underwent cholecystectomy in Jinshan Hospital, Fudan University from August 2020 to November 2023 were selected, and were divided into acute cholecystitis group (n＝192) and chronic cholecystitis group (n＝105). The patients in acute cholecystitis group were further divided into severe subgroup (n＝114) and mild subgroup (n＝78). The differential diagnosis values of SII and neutrophil-to-lymphocyte ratio (NLR) in acute and chronic cholecystitis were evaluated by ROC curve.

Results Compared with chronic cholecystitis group, males were more, older, the incidence of hypertension was higher, drainage volume increased, drainage time, hospital time, and surgical duration were all longer, blood cells, neutrophil count, monocyte count increased, total bilirubin, direct bilirubin, and creatinine were higher, SII and NLR increased in the acute cholecystitis group (P<0.05). Compared with the severe subgroup, the drainage volume decreased, drainage time, hospital stay, and surgical duration were shorter, white blood cell count, neutrophil count, monocyte count, and total bilirubin decreased, while lymphocyte count increased, SII and NLR decreased in the mild subgroup (P<0.05). The optimal cutoff values of SII and NLR for distinguishing acute cholecystitis from chronic cholecystitis were 797.96 and 3.65, and the AUC were 0.847 and 0.869, with 73.2% and 74.2% of sensitivity, and 86.7% and 89.5% of specificity. The optimal cutoff values of SII and NLR for distinguishing acute severe cholecystitis from mild cholecystitis were 1 056.59 and 4.65, the AUC were 0.768 and 0.779, with 77.0% and 82.3% of sensitivity, and 67.5% and 62.3% of specificity. There was no statistically significant difference between the values of SII and NLR for distinguishing acute severe and acute cholecystitis.

Conclusion SII is a good hematological indicator for distinguishing acute cholecystitis from chronic cholecystitis with similar value to NLR.