Neutrophil-to-lymphocyte Ratio, Platelet-to-lymphocyte Ratio, C-reactive Protein to Albumin Ratio, and Albumin to Fibrinogen Ratio in Axial Spondyloarthritis: A Monocentric Study

Background: C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) are routinely used to assess disease activity in spondyloarthritis. New biomarkers have been reported, such as neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), CRP to albumin ratio (CAR), and albumin to fibrinogen ratio (AFR). Aims: Our study aimed to assess these ratios in spondyloarthritis and to determine the relationship between these ratios and the disease activity. Methods: We conducted a cross-sectional study, including patients with spondyloarthritis. The following ratios were calculated: PLR, NLR, AFR, and CAR. Pearson correlation analysis was carried out to test the correlation of the data. Receiver operating characteristic curves were evaluated for each ratio using ASDASCRP as the gold standard for disease activity. Results: Eighty-five patients were included. The sex ratio was 60 males to 25 females. The mean age was 42.58 ± 11.75 years. There was a positive correlation between the PLR and the following parameters: CAR, CRP, and ESR. A negative correlation was found between AFR and the following ratios: PLR, NLR, CRP, and ESR. The ASDAS correlated negatively with AFR and positively with both PLR and CAR. The cutoff values of CAR and PLR to distinguish patients with very high disease activity (ASDASCRP>3.5) were 0.442 and 173.64, respectively. Conclusions: Given their good correlation with ESR and CRP, we suggest that PLR, CAR, and AFR can be used as potential indicators of inflammation in spondyloarthritis. The CAR and PLR are useful to identify patients with very high disease activity.