Peripheral blood neutrophil-to-lymphocyte ratio in inflammatory bowel disease and disease activity: A meta-analysis

The peripheral blood neutrophil-to-lymphocyte ratio (NLR) is a valuable predictor of clinical disease activity in inflammatory bowel disease (IBD). Therefore, we conducted a meta-analysis to evaluate the clinical significance of peripheral blood NLR in IBD patients.A comprehensive literature search was conducted by searching PubMed, Embase, Web of Science, Cochrane Library, and Chinese databases from inception to May 10, 2021. We used the standard mean difference (SMD) with a 95% confidence interval (CI) to estimate the pooled effect and subgroup analysis to investigate heterogeneity.Sixteen studies including 2185 IBD patients and 993 healthy controls (HCs) were enrolled in this study. The peripheral blood NLR values were significantly higher in 1,092 IBD patients than in 933 HCs (SMD = 1.54, 95% CI = 1.05-2.02, P < 0.001) and in 1,269 patients with active IBD than in 1,056 patients with remissive IBD (SMD = 1.55, 95% CI = 1.06-2.05, P < 0.001). Subgroup analysis of the major subtypes of IBD revealed significantly elevated peripheral blood NLR values in patients with active ulcerative colitis (UC) compared to HCs (SMD = 2.04), remissive UC than HCs (SMD = 0.63), and active UC than in those with remissive UC (SMD = 1.32) (P < 0.05). Both Crohn's disease (CD) patients and active CD patients had significantly elevated peripheral blood NLR values than HCs with the SMD of 0.52 and 3.53 (P < 0.001).Peripheral blood NLR could serve as a valuable biomarker for predicting disease severity in IBD patients.