The neutrophil-to-lymphocyte ratio in rheumatoid arthritis: The dual perspectives from literature and clinic

The aim of this study was to elucidate the research direction and application value of neutrophil-to-lymphocyte ratio (NLR) as an emerging inflammatory marker in rheumatoid arthritis (RA) from both literature and clinical perspectives. Firstly, we made an extensive analysis in terms of the number of publications, highly cited literature, co-cited references, and keywords. Subsequently, a retrospective exploration of clinical data of 1490 patients with rheumatic diseases admitted to the First Affiliated Hospital of Anhui University of Chinese Medicine was conducted. Logistic regression models were used to explore the independent predictive role of NLR in different scenarios. Nomogram was developed and the model was clinically evaluated by recipient operating characteristic (ROC) curves, calibration plots and decision curve analysis. In addition, association rule analysis and Mantel test were used to determine associations between NLR and clinical characteristics and self-perception of patients. A total of 544 articles were retrieved, focusing on the pathophysiology and clinical studies of RA-NLR, such as “disease activity,” “inflammation” and “classification.” Retrospective analysis demonstrated that NLR, erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels were significantly higher in RA patients than in non-RA patients. Logistic regression models identified gender, age, NLR, ESR and CRP as independent predictors of RA. The ROC curve determined a cutoff value of 2.258 for NLR and a maximum area under the curve of 0.736. Both association rule analysis and Mantel test showed that NLR was highly correlated with inflammatory markers such as ESR, CRP, and self-perception scale scores before and after treatment. NLR > 2.258 was a meaningful risk factor for moderate-to-severe pain and higher disease activity, which predictive reliability was further confirmed in subgroup stratification analyses. NLR, as a novel inflammatory marker, correlates with clinical characteristics and self-perception of RA patients, acting as an independent predictor of RA diagnosis and activity assessment.