Cystatin D serum level in rheumatoid arthritis and its relation to disease activity

Abstract
Background
Rheumatoid arthritis (RA) is a chronic autoimmune condition that causes synovitis and functional impairment. Currently, the most often utilized biomarkers for monitoring disease activity and severity are acute phase proteins, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP).
However, discrepancies have been found between the clinical inflammation and their levels. Therefore, there is a strong need for a novel biomarker to forecast how RA will proceed clinically and monitor the response to therapy. This study assessed the diagnostic value of serum cystatin D in RA patients and its potential as a biomarker for disease activity monitoring.

Results
RA patients had considerably greater serum levels of cystatin D than the control group. These values showed a positive correlation with Disease Activity Score-28 (DAS28), ESR, CRP, grayscale synovitis, power Doppler synovitis, grayscale tenosynovitis (p < 0.001), and erosions, sum scores (p < 0.05). Nonetheless, no noteworthy association was observed between the serum cystatin D levels and sociodemographic data, rheumatoid factor (RF), and anti-cyclic citrullinated peptide (anti-CCP).

Conclusion
Cystatin D serum levels are higher in RA patients compared to healthy subjects and are strongly correlated with the activity of RA. It can be a valuable biomarker for evaluating RA disease activity.