Background
Acute cholecystitis accounts for most of the hospital admissions related to gastrointestinal diseases. In approximately 90% of patients, inflammation develops due to obstruction of the cystic duct by one or more gallstones. Delayed management can lead to increased morbidity, due to progression to severe cholecystitis, such as gangrenous change, abscess formation, and gallbladder perforation. The prevalence of severe cholecystitis has been reported to be 22–30% in surgical series. Unfortunately, patients with severe cholecystitis are often challenging to accurately diagnose, both clinically and radiologically, since the clinical manifestations are unpredictable, and imaging studies are often equivocal. However, marked contrasts in the morbidity and mortality rates have been observed beween patients with simple cholecystitis and severe cholecystitis. Therefore, prompt detection and proper management of patients at risk of severe cholecystitis are essential in preventing associated complications.
To predict the prognosis of inflammatory diseases and some malignancies, several inflammation-based scores have been suggested, including the Modified Glasgow Prognostic Score, neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio, and prognostic Nutritional Index. Of these, the NLR has received great interest, since it is simple to calculate, and involves no additional cost, as it uses results from a standard complete blood count test. The NLR is derived from the counts of circulating neutrophils and lymphocytes, both of which are major leukocyte subpopulations. The inflammation-triggered release of arachidonic acid metabolites and platelet-activating factors results in neutrophilia, and cortisol-induced stress results in relative lymphopenia, and thus, the NLR accurately represents the underlying inflammatory process. Increasing evidence supports the utility of the NLR in predicting the prognosis of inflammatory and malignant diseases, although the application of the NLR to inflammatory gallbladder disease has not been reported. In the present study, we aimed to evaluate the utility of the NLR as a prognostic indicator in patients with cholecystitis, and to identify a relevant NLR value that discriminates between simple and severe cholecystitis.