To systematically evaluate the clinical efficacy of neutrophil to lymphocyte ratio (NLR) in the early prediction of severe acute pancreatitis (SAP) based on the revised Atlanta classification.

A systematic search was conducted using CNKI, Wanfang, VIP, PubMed, Web of Science, Cochrane library and Embase databases from the date of establishment to January 2021. Two independent authors evaluated the eligibility of the studies and performed data extraction. The QUADAS-2 was used to assess the quality of diagnostic accuracy studies included in this meta-analysis. Statistical analyses were performed using the STATA 15.1 and Meta-DiSc1.4 software. Pooled sensitivity, specificity, positive likelihood ratio (LR+), negative likelihood ratio (LR-), diagnosis of odds ratio (DOR) and symmetric receiver operator characteristic (SROC) curves, as well as the area under the SROC curve (AUC), were assessed using the bivariate mixed effects models.

Totally 12 studies with 2 299 patients were included, containing 337 SAP patients. The pooled sensitivity, specificity, LR+, LR- and DOR of the NLR for predicting SAP were 0.79 (95% CI: 0.72-0.84), 0.76 (95% CI: 0.70-0.81), 3.26 (95% CI: 2.64-4.03), 0.28 (95% CI: 0.22-0.37), 11.55 (95% CI: 7.93-16.81), respectively. The AUC was 0.84 (95% CI: 0.81-0.87).

NLR is a readily available and convenient marker reflecting the level of systemic inflammatory response, with a certain clinical value in early prediction of SAP.