AB0566 PERFORMANCE OF THE NEUTROPHILS-TO-LYMPHOCYTES RATIO AS A BIOMARKER OF DISEASE ACTIVITY IN RHEUMATOID ARTHRITIS – DATA FROM THE REAL STUDY
Authors: C. Albuquerque, V. Cruz, T. R C M Morais, A. P. Gomides, R. D. Neubarth Giorgi, L. Pereira, S. Radominski, I. Pereira, M. F. Guimarães, M. Bertolo, P. Louzada, M. D. F. Sauma, K. Bonfiglioli, C. Brenol, L. Mota, G. Castelar-Pinheiro
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> Systemic inflammation is often associated with changes in counts of circulating blood cells, including neutrophils and lymphocytes, thus making the neutrophils-to-lymphocytes ratio (NLR) a potential biomarker of disease activity in rheumatoid arthritis (RA). The widely adopted treat-to-target (T2T) strategy in RA seeks the goal of attaining remission or, at least, low disease activity (LDA) in all patients. However, few studies have evaluated the role of NLR in guiding T2T decisions. <h3>Objectives:</h3> To analyze the usefulness of NLR as a biomarker of inflammatory disease activity, and its performance in discriminating between patients who had achieved vs. not achieved the T2T goal. <h3>Methods:</h3> This was a sub-analysis of the baseline data from the REAL study, which enrolled adults meeting ARA (1987) or ACR/EULAR (2010) classification criteria for RA, attending 11 reference centers in Brazil, who were interviewed and had laboratory evaluations. The 28-joint disease activity score (DAS28) with erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), the simplified disease activity index (SDAI), and the clinical disease activity index (CDAI) were used as reference tools to evaluate disease activity, and to classify the participants into two groups: T2T achieved vs. T2T not achieved, based on whether or not they had attained the goal of T2T strategy. NLR was calculated as dividing the absolute counts of circulating neutrophils by lymphocytes. Receiver operating characteristic (ROC) curves were used to assess the performance of NLR in discriminating between those two groups (T2T achieved vs. not-achieved), and to find a cutoff for NLR that would optimize the balance between its sensitivity and specificity. Other performance metrics of NLR against the reference tools were calculated from confusion matrices. Pearson's correlation and students' t tests were applied to verify associations between NLR and the disease activity scores. The study received ethical approval. <h3>Results:</h3> From the 1115 participants in the REAL study, 557 (49.9%) had complete blood counts, thus entering this sub-analysis; 90.7% (n=505) were females; 60.3% (n=336) white; 79.7% (n=440) had positive rheumatoid factor. Mean (SD) age was 57.3 (10.8) years; disease duration 14.7 (9.5) years. The mean (SD) scores for DAS28-ESR, DAS28-CRP, CDAI and SDAI were 3.5 (1.4), 3.3 (1.3), 12.2 (10.9) and 13.8 (11.4) respectively; for NLR 2.5 (1.5). The median [Q1, Q3] CRP was 0.70 [0.26, 1.87] mg/dL. NLR showed positive correlation with DAS28-ESR (r=0.112, p=0.013), DAS28-PCR (r=0.177, p&lt;0.001), CDAI (r=0.113, p=0.008), SDAI (r=0.167, p&lt;0.001) and CRP (r=0.277, p&lt;0.001). NLR was significantly higher in participants who had NOT achieved the T2T goal compared to those under the T2T goal, for most reference tools: for DAS28-ESR (mean difference = 0.14, 95%CI [-0.11, 0.39], p=0.270), DAS28-PCR (0.49 [0.22, 0.75], p &lt; 0.001), CDAI (0.29 [0.03, 0.55], p = 0.028) and SDAI (0.41 [0.15, 0.66], p = 0.002). ROC curves (Figure 1) revealed NLR as a poor discriminator between the statuses of T2T goal achieved vs. not achieved, with low area under the curve (AUC) for all reference tools considered; the cutoff for NLR with the best balance between sensitivity and specificity was found at 2.13. Other metrics derived from confusion matrix analyses confirmed the poor performance of NLR in discriminating between T2T goal achieved vs. not achieved, whatever the reference tool utilized to define T2T goal achievement (Table 1). <h3>Conclusion:</h3> NLR is a potentially useful biomarker of ongoing inflammatory process in RA, as it correlated positively with clinical disease activity scores, and its levels were elevated in individuals with moderate or high disease activity. However, NLR exhibited poor performance in discriminating between participants who had achieved remission/ LDA, and those who had failed to achieve such goals. Clinical decisions regarding the modification of treatment in RA, therefore, should not rely solely on NLR. <h3>REFERENCES:</h3> <b>NIL.</b> <h3>Acknowledgements:</h3> <b>NIL.</b> <h3>Disclosure of Interests:</h3> <b>None declared.</b>