Serum Dickkopf-1 levels in patients with rheumatoid arthritis: relationship with disease activity and interstitial lung disease

Objectives. This study aimed to determine whether blood levels of Dickkopf-1 (DKK-1) in RA patients are associated with disease activity and interstitial lung disease (RA-ILD). Materials and methods. This cross-sectional exploratory study was conducted on 30 healthy controls and 60 RA patients, subdivided into two groups: 30 without RA-ILD and 30 with RA-ILD. Disease activity was assessed using the DAS28 score. Serum DKK-1 levels in patients and controls were measured. Patients in group 2 underwent HRCT of the chest and, if necessary, pulmonary function testing. Outcomes. Group 2 had a significantly higher mean serum DKK-1 level than both group 1 and the controls (p < 0.001). Serum DKK-1 showed 76.6% sensitivity and 83.3% specificity for RA, and 83.33% sensitivity and 96.67% specificity for RA-ILD. Serum DKK-1 levels were significantly positively correlated with morning stiffness duration in both groups. DKK-1 levels were significantly higher in group 2 patients with positive anti-CCP antibody testing than in those with negative results (p = 0.035). Conclusions. Serum DKK-1 levels may serve as a biomarker associated with disease activity in RA. They also show potential diagnostic value for RA-ILD, which may contribute to earlier diagnosis and improved understanding of pathophysiology, and may represent a potential therapeutic target. The relatively small sample size and cross-sectional design represent important limitations. Further large-scale longitudinal studies are needed to validate these findings and clarify their clinical relevance.