Characterization of neutrophil‐to‐lymphocyte ratio as a measure of inflammation in rheumatoid arthritis

OBJECTIVES: The neutrophil to lymphocyte ratio (NLR) is one of the well-recognized sensitive measures of inflammation. This cross-sectional observational study was aimed at characterizing the relationship of NLR with the inflammatory markers erythrocyte sedimentation rate (ESR), C-reative protein (CRP), Disease Activity Score of 28 joints (DAS28)-CRP(3), joint counts and quality measures of rheumatoid arthritis (RA). MATERIALS AND METHODS: Patients with RA were recruited in two phases. The following were assessed for all patients: joint count, pain by visual analogue scale (VAS), complete blood count, ESR, CRP and quality index assessment using the Short Form health survey (SF-36) questionnaire. A subgroup analysis was also performed to evaluate the association between NLR and cytokines. RESULTS: Four hundred and eighty-nine subjects were recruited. Distribution of NLR values corresponded with DAS28-CRP(3) rather than CRP and ESR. A significant difference in VAS, swollen joint counts (SJC-28), inflammatory parameters and general health outcome measures was observed among the NLR groups. A weak correlation was observed between NLR and RA disease measures. It had least bias at lower ranges with DAS28-CRP(3) than CRP and ESR. The NLR cut-off value of 1.4 classified the patients in deep remission with 90% specificity, 24% sensitivity, likelihood ratio positive (LR+) 2.46 and likelihood ratio negative (LR-) 0.84. CRP was a significant baseline predictor of NLR. A significant influence of interleukin-6 on CRP was noted. CONCLUSION: In contrast to the traditional markers, NLR may serve as a less expensive and effective measure of inflammation in RA. Its efficacy is comparable to that of CRP and it is not impacted by the cytokines influencing CRP and ESR.