Analysis of the association between the neutrophil-to-lymphocyte ratio (NLR) and liver injury complicating acute pancreatitis: a retrospective study.

BACKGROUND

Acute pancreatitis is frequently complicated by acute liver injury (ALI), which exacerbates systemic inflammation and increases mortality. Early identification of high-risk patients remains challenging. The neutrophil-to-lymphocyte ratio (NLR) is a simple marker of systemic inflammation, but its association with ALI in acute pancreatitis is unclear.

OBJECTIVES

To investigate the association between NLR and ALI in acute pancreatitis and evaluate its predictive value.

METHODS

Clinical data from 581 acute pancreatitis inpatients (2021-2025) were retrospectively analyzed. Multivariate logistic regression, generalized additive models, subgroup analyses, interaction tests, and ROC curves were used.

RESULTS

ALI occurred in 37.7% of patients. After adjustment, each one-unit NLR increase raised ALI risk by 11% (OR = 1.11, 95% CI: 1.08-1.14, P < 0.001). The highest NLR quartile had a 5.42-fold higher risk than the lowest. A non-linear threshold was identified at NLR = 2.92: risk rose sharply below this point (OR = 6.55) and more gradually above it (OR = 1.07), suggesting that even a mild NLR elevation may signal early liver injury risk. NLR alone predicted ALI with AUC = 0.688 (cutoff 8.26, sensitivity 59.4%, specificity 68.0%). Adding CRP and gallstones improved AUC to 0.756 (sensitivity 65.8%, specificity 76.2%), indicating that combining inflammatory markers with etiological factors enhances predictive accuracy.

CONCLUSION

NLR independently predicts ALI in acute pancreatitis with a non-linear threshold effect. NLR ≥ 2.92 can serve as an early warning signal to initiate enhanced liver function monitoring, while NLR ≥ 8.26 identifies patients at high risk. Combining NLR with other readily available indicators significantly improves predictive performance and may facilitate early clinical decision-making.