Neutrophil percentage-to-albumin ratio as a predictor of conservative treatment failure in acute cholecystitis: a retrospective cohort study

Abstract

Background: While early laparoscopic cholecystectomy is the standard treatment for acute cholecystitis, conservative management remains necessary in specific scenarios such as high-risk patients or resource-limited settings. This study evaluated the predictive value of neutrophil percentage-to-albumin ratio (NPAR), a biomarker derived from routine laboratory tests, alongside established inflammatory markers and clinical parameters in identifying patients at risk of conservative treatment failure. Methods: In this retrospective cohort study at 2 tertiary centers (2020–2023), we analyzed 508 patients with acute cholecystitis who received conservative management. The study period coincided with the COVID-19 pandemic when healthcare resource constraints led to increased utilization of conservative management. Using admission laboratory data, we calculated NPAR, neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and assessed Charlson Comorbidity Index (CCI) and American Society of Anesthesiologists Physical Status (ASA-PS) classification. Receiver operating characteristic analysis and logistic regression were performed to evaluate their predictive value. Results: Conservative treatment failed in 107 patients (21.1%). Risk assessment showed higher proportions of CCI ≥ 6 (32.7% vs. 22.9%; P =.008) and ASA-PS class III-IV (16.8% vs. 8.0%; P =.002) in the failed treatment group. NPAR demonstrated superior predictive performance (area under curve, 0.906 [95% CI, 0.867–0.944]) compared with NLR (0.810 [0.765–0.855]) and PLR (0.614 [0.554–0.673]). The optimal NPAR cutoff value of 21.5 showed sensitivity of 88.8% and specificity of 84.8%. In multivariable analysis, NPAR > 21.5 emerged as the strongest independent predictor (adjusted odds ratio, 19.876 [95% CI, 8.934–42.651]; P <.001), followed by fever > 37.8 °C (2.845 [1.476–5.483]; P =.002) and leukocytosis (2.234 [1.112–4.485]; P =.024). Most treatment failures (77.6%) occurred within 48 h, requiring emergency surgery (57.9%), percutaneous drainage (37.4%), or endoscopic interventions (4.7%). Conclusions: NPAR, combined with fever and leukocytosis, provides a practical and cost-effective framework for predicting conservative treatment failure in acute cholecystitis using routine laboratory tests. Although our study was conducted during the COVID-19 pandemic, these findings remain valuable for any clinical setting where conservative treatment is considered. The 48-hour window for most treatment failures provides a practical timeframe for clinical monitoring and intervention decisions.