Several biochemical markers can predict radiographic progression in rheumatoid arthritis (RA). Serum matrix metalloproteinase 3 (MMP-3) and urinary C-telopeptide of type II collagen (CTX-II) are better predictors than are traditional markers.
Young-Min and colleagues conducted a 2-year prospective study of 132 patients with early RA. Patients were treated with disease-modifying antirheumatic drugs and adjunctive corticosteroids. At each visit, measures of disease activity were recorded and serum and urine samples were obtained. Genomic DNA was obtained from venous blood samples. Complete sets of radiographs were obtained for 118 patients.
There was radiographic progression in 50 patients and no radiographic progression in 68 patients. Levels of a variety of biochemical markers correlated significantly with radiographic progression at entry and longitudinally by area under the curve analysis. By subsequent multivariate analysis, elevated MMP-3 and urinary CTX-II levels were identified as the only 2 independent baseline factors that predicted radiographic progression. In 50 patients treated with methotrexate during the follow-up, median serum MMP-3 levels decreased after the initiation of therapy.
The authors noted that these biomarkers do not yet have a role in routine clinical practice but in the future may provide a cost-effective alternative to traditional disease activity assessment and imaging methods.