Neutrophil lymphocyte ratio in patients with ankylosing spondylitis: A systematic review and meta-analysis.

Objective: The aim of this meta-analysis was to investigate the association of neutrophil lymphocyte ratio (NLR) with AS (ankylosing spondylitis) patients.Methods: PubMed, Web of Science, Cochrane Library, Elsevier Science Direct and Google Scholar databases (up to 30 September 2018) were searched to collect all pertinent articles. The pooled standard mean difference (SMD) with 95% confidence interval (CI) was calculated by the random effects model.Results: Totally 10 studies contained 765 AS patients and 701 healthy controls were included in our meta-analysis. The results indicated that there were significant statistical differences between AS patients and healthy controls in NLR (SMD = 0.418, 95%CI = 0.239-0.598, p < .001). Meanwhile, the results of subgroup analysis showed, in the subgroup of C-reactive protein (CRP) ≥10 and the two subgroups of BASDAI (the Bath AS Disease Activity Index), NLR levels in AS were significantly higher than in control (all p < .001). The results of subgroup analysis and meta-regression suggested that BASDAI and CRP were likely associated with NLR in AS patients.Conclusion: The current meta-analysis provides evidence that NLR is a reasonable measure to detect systemic inflammation in AS patients. Besides, NLR may be able to indicate disease activity in patients with AS.