Background Digital X-ray Radiogrammetry (DXR) is a computer based technique to quantify cortical hand bone mineral density (BMD) as well as metacarpal index (MCI) at the metacarpal bones from radiographs in patients with rheumatoid arthritis (RA).
Objectives The objective was to compare DXR-BMD and DXR-MCI between healthy individuals and patients with RA and verify the sensitivity and specificity of this technique for the identification of cortical hand bone loss as an additional diagnostic approach in RA.
Methods In total, 976 patients were enrolled and divided into two groups; those with RA (n=333) and a healthy control group (n=643) as a reference data base. Bone DXR-BMD and the DXR-MCI were measured by DXR using hand radiographs. Severity of RA was evaluated by the modified Larsen Score.
Results The mean values for DXR-BMD and DXR-MCI in RA patients were significantly lower compared to the healthy subjects (23.7% and 22.7%). Depending on the severity of joint damage RA, DXR-BMD revealed a significant reduction of –27.9% and DXR-MCI –28.3%, comparing score 1 and Score 5 of the modified Larsen Score. Both DXR-BMD and DXR-MCI had a high sensitivity (DXR-BMD 95%; DXR-MCI 92%) and moderate specificity (DXR-BMD 48%, DXR-MCI 51%) to identify RA related cortical hand bone loss.
Conclusions The DXR-technique is able to quantify RA-related periarticular bone loss as a typical feature in the course of RA. Consequently, in this case periarticular osteoporosis seems to function as a reliable diagnostic approach comparable to erosions and joint space narrowing in the diagnosis of RA and as a surrogate marker for the progression of bone damage in RA.
Disclosure of Interest None declared