Neutrophil to lymphocyte ratio and platelet to lymphocyte ratio in patients with systemic lupus erythematosus and their correlation with activity: A meta-analysis.

Objective: The neutrophil to lymphocyte ratio (NLR) and platelet to lymphocyte ratio (PLR) have been suggested to be potential biomarkers for systemic lupus erythematosus (SLE). We thus performed this meta-analysis to investigate the relationship between NLR and PLR and SLE.

Methods: A literature review was conducted by searching the Pubmed, Embase, Cochrane and Wanfang online databases from inception to 1 June 2019. Studies were pooled and the standard mean difference (SMD) with 95% confidence interval (CI) was calculated using a random-effect or fixed-effect model.

Results: A total of fourteen studies were eventually included in the meta-analysis, of which nine (1246 SLE patients and 976 healthy controls) reported the NLR of SLE patients and healthy controls, six (646 SLE patients, 524 healthy controls) reported the PLR of SLE patients and healthy controls, nine (1128 SLE patients) reported the correlation coefficients between the NLR and SLE disease activity index (SLEDAI) in SLE patients, and six (715 SLE patients) reported correlation coefficients between PLR and SLEDAI in SLE patients. The NLR and PLR in SLE patients were significantly higher than in healthy controls (SMD = 1.004, 95%CI = 0.781-1.227, P < 0.001, SMD = 0.709, 95%CI = 0.58-0.838, P < 0.001), and were both positively correlated with SLEDAI (correlation coefficient = 0.429, 95%CI = 0.288-0.552, P < 0.001, correlation coefficient = 0.309, 95%CI = 0.091-0.498, P < 0.001, respectively).

Conclusion: NLR and PLR were significantly higher in SLE patients compared with healthy controls, and were positively correlated with SLEDAI, suggesting that NLR and PLR are useful biomarkers in the management of SLE.