Correlation of neutrophil-lymphocyte ratio, plateletlymphocyte ratio and mean platelet volume with disease activity in patients with ankylosing spondylitis

Abstract

Objectives: The indices that are currently used to determine the disease activity in patients with ankylosing spondylitis (AS) are either patient- or physician-oriented. The neutrophil–lymphocyte ratio (NLR), platelet–lymphocyte ratio (PLR) and mean platelet volume (MPV) are new markers of systemic inflammation and correlate with disease severity in many rheumatological disorders. However, their relationship with disease activity in patients with AS has not been thoroughly studied in the Indian subcontinent. Methods: This cross-sectional observational study was performed on 60 patients with definite AS in a tertiary care hospital in New Delhi, India. Healthy, age- and sex-matched individuals identified from the same demographic population were subjected to clinical assessment and investigations as per protocol. Results: The mean values of NLR, PLR and MPV were 3.13±1.1, 168.36±69.43 and 10.07±1.28, respectively, in cases with high disease activity as compared to 2.58±1.05, 127.02±55.65 and 10.07±1.64 in cases with low disease activity. A statistically significant correlation was found between NLR and PLR and disease activity as calculated by Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Metrology Index (BASMI), Bath Ankylosing Spondylitis Functional Index (BASFI) and Ankylosing Spondylitis Disease Activity Score-C-reactive protein/erythrocyte sedimentation rate (ASDAS-CRP/ESR). However, multivariate linear regression revealed a significant correlation only between NLR and BASDAI, BASFI and ASDAS-CRP. PLR was found to be significantly lower in cases on biological therapy. No correlation of PLR and MPV with disease activity was found on multivariate regression analysis. Conclusion: NLR and PLR correlate significantly with disease activity indices in patients with AS. Patients with the extraspinal disease had higher NLR, PLR and MPV with only NLR being statistically significant. NLR was significantly lower in patients on biologics than those on Disease modifying antirheumatic drugs (DMARDs). Therefore, NLR and PLR can be used as potential parameters for the assessment of disease activity and extra-spinal disease and treatment response monitoring in patients with AS.