Hematological Biomarkers and Disease Activity in Rheumatoid Arthritis: A Retrospective Cross-Sectional Study in Peruvian Patients

Abstract

Rheumatoid arthritis (RA) is a chronic inflammatory disease in which accurate assessment of disease activity is essential for optimizing treatment strategies. Hematological indices derived from routine blood tests, such as the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and systemic immune-inflammation index (SII), have been proposed as accessible markers of systemic inflammation. To investigate the association between NLR, PLR, and SII and disease activity in patients with RA. A total of 188 patients with RA from a tertiary referral center in Peru were included. Disease activity was assessed using the Disease Activity Score in 28 joints with C-reactive protein (DAS28-CRP) and serum C-reactive protein (CRP). The Spearman correlation analyses were performed to examine associations between hematological indices and disease activity measures. Multivariable generalized linear models were used to determine independent associations after adjusting for potential confounders, including age, sex, disease duration, corticosteroid dose, and disease-modifying antirheumatic drug (DMARD) therapy. Neutrophil-to-lymphocyte ratio, PLR, and SII showed significant positive correlations with DAS28-CRP ( r  = 0.66, r  = 0.47, and r  = 0.57, respectively) and CRP levels ( r  = 0.69, r  = 0.43, and r  = 0.62, respectively) (all P  < .001). In multivariable analyses, all 3 indices remained independently associated with both DAS28-CRP and CRP after adjustment for confounding variables (all P  < .001). Hematological indices such as NLR, PLR, and SII are significantly associated with disease activity in RA and may represent simple and cost-effective complementary biomarkers for disease monitoring, particularly in resource-limited settings like in Latin America. Retrospective cross-sectional study.