Is there a role for Digital X-ray Radiogrammetry as surrogate marker for radiological progression and imaging of structural integrity in rheumatoid arthritis?

Introduction The established scoring techniques based on radiographs present limitations in the evaluation of structural integrity due to high effectiveness of innovative therapeutic strategies. The aim of this study was to evaluate the periarticular mineralisation as detected by Digital X-ray Radiogrammetry (DXR) as surrogate marker for structural integrity during the course of rheumatoid arthritis (RA). Methods 11 centers throughout Germany contributed data of 94 patients with verified RA. The patients were treated with leflunomide or methotrexate during a mean observation period of 22 months. All patients underwent complete computerized calculations of bone mineral density (BMD) and metacarpal index (MCI) by DXR using digitized hand radiographs. The radiological assessment of disease progression was estimated by the Sharp Score. Results The Sharp Score revealed no significant change during the study period. DXR-BMD revealed minimal decrease of −1.4 % (leflunomide group) versus a higher reduction of −4.3 % (methotrexate group). Regarding DXR-MCI, a reduction of −2.2 % (leflunomide group) and −4.9 % (methotrexate group) was observed. Conclusion Quantitative data of hand bone mass estimated by the presented DXR-technique may be a complementary precise tool in the identification of RA-related radiographic changes and in the assessment of structural integrity.