Meta-analysis finds elevated neutrophil-to-lymphocyte ratio in SLE, with weak correlation to disease activity

This meta-analysis of 40 studies, with external validation from a single-center study of 290 patients, evaluated the diagnostic and discriminative value of neutrophil-to-lymphocyte ratio (NLR) in systemic lupus erythematosus (SLE). The analysis compared NLR levels in SLE patients versus healthy controls and examined its association with lupus nephritis, active disease, and SLEDAI scores.

NLR was significantly higher in SLE patients compared to healthy controls, with a standardized mean difference of 0.850. Patients with lupus nephritis and active disease also exhibited elevated NLR. A positive correlation was found between NLR and SLEDAI scores, with a pooled correlation coefficient of 0.330, though this decreased to 0.200 after trim-and-fill adjustment for publication bias. External validation showed a correlation of 0.210. The discriminatory accuracy of NLR was generally limited, with area under the curve values ranging from 0.668 to 0.757.

Safety and tolerability data were not reported. Key limitations include significant heterogeneity attributed to patient ethnicity and treatments. The authors conclude that NLR should not be used as an independent biomarker but may have a role as part of a combined assessment. The findings represent an association, not causation, and clinical utility is limited by the weak correlation and influence of confounding factors.