Disease Activity Score (DAS) Correlation to Serum Prolidase as a Collagen Turnover Marker in Comparison to Some Pro-inflammatory Markers in Rheumatoid Arthritis Patients: Clinical and Sonographic Study

Objectives: Disease activity score (DAS) correlation to serum prolidase in comparison to other pro-inflammatory markers in rheumatoid arthritis (RA) cases.

Method: Forty RA cases and 40 age and sex matched controls were studied in this case-control study. Cases fulfilled the 2010 American college of rheumatology (ACR)/ European League Against rheumatism (EULAR) RA classification criteria. Disease activity was assessed by the disease activity score 28 (DAS 28). Ultrasound (US) scanning of synovitis in pre-selected joint was done in both gray scale (GS) and power doppler US (PDUS) modes.

Results: The cases’ mean age was 50.05 ± 7.99 years, 52 females and 28 males participated in this study. The mean disease duration was 6.10 ± 3.89 years and the mean for the DAS-28 score was 4.85 ± 1.04. There was a significant correlation between CRPM and DAS 28 score (r=0.323, p=0.042). IL-6 correlated with GS synovitis in the wrist (r=0.376, p= 0.017), MCP (r=0.430, p= 0.006) and PIP (r=0.653, p=<0.001) joints. Serum prolidase correlated with both GS synovitis in the wrist (r= 0.486, p=0.001) and MCP (r=0.604, p=<0.001) and PDUS synovitis in the wrist (r=0.334, p=0.035), and MCP joints (r=0.456, p=0.003). Regression analysis showed that IL-6 level had a greater impact on GS synovitis (p= <0.001), compared with serum prolidase.

Conclusions: Serum IL-6 and prolidase has significant correlations with disease activity parameters compared with other markers. Serum prolidase is evidence on increased collagen turnover in RA cases and might be a useful tool in the assessment of joint inflammation and predicting future damage.