C-reactive protein/albumin ratio and its improvement with disease activity among axial spondyloarthritis and psoriatic arthritis patients: A prospective study

Background: The C-reactive protein /albumin ratio (CAR) has emerged as a novel biomarker in inflammatory conditions. Aim of the work: To assess the association of CAR with disease activity and its possible role as a biomarker for improvement among Axial spondyloarthritis (axSpA) and Psoriatic Arthritis (PsA) patients. Patients and methods: The study was conducted on 85 axSpA and 51 PsA patients. C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), albumin, CAR, and the AS disease activity score (ASDAS) as well as the disease activity PsA (DAPSA) score measures were calculated at baseline and after three months during the follow-up visit. Results: The CAR significantly correlated with the ASDAS in axSpA patients (r = 0.58, p < 0.001) and had a tendency to correlate with the DAPSA in the PsA group. (r = 0.1, p = 0.47). There was a fair agreement between CAR and ASDAS improvements. However, CAR was not suitable for the assessment of improvement in axSpA patients compared to both ASDAS and ASDAS clinically important improvement (ASDAS-CII) (sensitivity:86 %, specificity:46.9 %, accuracy:70.7 %, and sensitivity: 14 %, specificity: 75 %, accuracy: 37.8 %, respectively) or in PsA patients compared to both DAPSA improvement and response (sensitivity: 90 %, specificity: 30 %, accuracy: 78 % and sensitivity: 30 %, specificity: 70 %, accuracy: 38 %, respectively). Conclusion: The CAR is a simple rapid inexpensive objective test for evaluating the disease activity in axSpA rather than in PsA. On follow-up, the CAR improvement was unsuitable to assess improvement among axSpA and PsA patients.