Relationship between Neutrophil-to-Lymphocyte Ratio and Systemic Lupus Erythematosus: A Meta-analysis

Systemic lupus erythematosus (SLE) is a chronic systematic autoimmune disease. Current methods of diagnosing SLE or evaluating its activity are complex and expensive. Numerous studies have suggested that neutrophil-to-lymphocyte ratio (NLR) is closely correlated with the presence of SLE and its activity, suggesting that it may serve as a diagnostic and monitoring indicator for SLE. Therefore, we performed a meta-analysis to systematically assess the association between NLR and SLE. We performed a literature search until 12 April 2019 in the PubMed, Web of Science, and China National Knowledge Infrastructure databases. Cross-sectional studies comparing the NLR of SLE patients versus those of healthy controls, of active versus inactive SLE patients, and of SLE patients with versus without lupus nephritis were considered for inclusion. Mean intergroup NLR differences were estimated using standardized mean differences and their 95% confidence intervals. Study quality was assessed using the Agency for Healthcare Research and Quality instrument for cross-sectional studies. Fourteen studies with 1,781 SLE patients and 1,330 healthy controls were included in this meta-analysis. The pooled results showed that the NLR was significantly higher in SLE patients than in healthy controls, in active SLE patients than in inactive SLE patients, and in SLE patients with lupus nephritis than in those without lupus nephritis. NLR may be an indicator for monitoring disease activity and reflecting renal involvement in SLE patients. Nevertheless, more high-quality studies are warranted to further validate our findings.