The Neutrophil-Lymphocyte Ratio as an Early Predictive Marker of the Severity of Post-Endoscopic Retrograde Cholangiopancreatography Pancreatitis

Background and objectives: Factors predictive of severe non-iatrogenic acute pancreatitis have been investigated, but few studies have evaluated prognostic markers of severe post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis (PEP). The neutrophil–lymphocyte ratio (NLR) has been studied for predicting severe acute pancreatitis. We examined the predictive value of NLR in patients with PEP. Materials and Methods: From January 2012 to August 2021, 125 patients who developed PEP were retrospectively evaluated. The NLR was measured before, and on days 1 and 2 after, ERCP. PEP was categorized as mild, moderate, or severe according to consensus guidelines, based on the prolongation of planned hospitalization. Patients were divided into two groups, mild-to-moderate vs. severe PEP. Results: We analyzed 125 patients with PEP, 18 (14.4%) of whom developed severe PEP. The baseline NLR was similar between the two groups (2.26 vs. 3.34, p = 0.499). The severe PEP group had a higher NLR than the mild/moderate PEP group on days 1 (11.19 vs. 6.58, p = 0.001) and 2 (15.68 vs. 5.32, p < 0.001) post-ERCP. The area under the curve of the NLR on days 1 and 2 post-ERCP for severe PEP was 0.75 (95% confidence interval (CI), 0.64–0.86)) and 0.89 (95% CI, 0.81–0.97), respectively; NLR on day 2 had greater power to predict severe PEP. The optimal cutoff value of the NLR on days 1 and 2 after ERCP for prediction of severe PEP was 7.38 (sensitivity, 72%; specificity, 69%) and 8.17 (sensitivity, 83%; specificity, 83%), respectively. In a multivariate analysis, a Bedside Index of Severity in Acute Pancreatitis score ≥3 (odds ratio (OR) 9.07, p = 0.012) and NLR on day 2 > 8.17 (OR 18.29, p < 0.001) were significantly associated with severe PEP. Conclusions: The NLR on day 2 post-ERCP is a reliable prognostic marker of severe PEP.