Prognostic value of the acute-phase reactant index in predicting severity and clinical outcomes in acute cholecystitis patients presenting to the emergency department: A retrospective observational study.

Acute cholecystitis is a common inflammatory condition encountered in emergency departments (EDs), with severity varying widely among patients. Rapid risk stratification and appropriate management are critical in preventing complications and mortality. This study aimed to evaluate the association between the acute-phase reactant index (APhRI) and disease severity, and to investigate the potential prognostic value of APhRI in clinical decision-making. We conducted a single-center, retrospective observational study of adult patients diagnosed with acute cholecystitis in a tertiary ED between January 2024 and January 2025. APhRI was calculated as (C-reactive protein [CRP] × procalcitonin [PCT])/ albumin. Patients were stratified according to the Tokyo Guidelines 2018 (TG18). Statistical analyses included chi-square/Fisher exact tests, t-test/Mann-Whitney U test, receiver operating characteristic curve analysis, and DeLong test. A total of 547 patients were included. According to TG18, 28.7% were classified as moderate-to-severe acute cholecystitis. APhRI levels were significantly higher in these patients. The area under the curve of APhRI for predicting severity was 0.687, superior to CRP (0.673), PCT (0.567), and albumin (0.618) (P < .05 for all). Higher APhRI values were also observed in patients requiring surgery (P = .008) or interventional radiology (P < .001), and positively correlated with hospital stay (ρ = 0.327, P < .001). APhRI appears to be a practical and useful biomarker not only for predicting severity in acute cholecystitis but also for supporting early triage and treatment decisions in the ED.