InternatIonal journal of BIomedIcal scIence Metacarpal Index Estimated by Digital X-ray Radiogrammetry as a Tool for Differentiating Rheumatoid Arthritis Related

AbstrAct to investigate Metacarpal Index (McI) and bone Mineral Density (bMD) estimated by Digital X-ray radio-grammetry (DXr) with respect to its ability to quantify severity-dependent variations of bone mineralisation in patients with early rheumatoid arthritis compared to Dual Energy X-ray Absorptiometry (DXA), 122 patients underwent a prospective analysis of bMD and McI by DXr, whereas both DXr-parameters were estimated from plain radiographs of the non-dominant hand. In comparison DXA measured bMD on total femur and lumbar spine (L2-L4). Additionally steinbrocker stage was assessed to differentiate the severity of rheumatoid arthritis (rA). Disease activity of rA was estimated by c-reactive Protein (crP; in mg/l), Erythrocyte sedimen-tation rate (Esr in mm/1st hour) and by the disease activity score with 28-joint count (DAs 28). In consequence, The DXR-parameters, in particular DXR-MCI, revealed significant associations to age, Body Mass Index, CRP, DAS 28 and Steinbrocker graduation; no significant associations could be verified between DXA-parameters and all characteristics of disease activity and severity of rA. the highest correlation was found between DXr-McI and DXR-BMD with R=0.89 (independent from severity of RA). In all patients DXR-MCI significantly decreased (-14.3%) from 0.42 ± 0.09 (stage 1) to 0.36 ± 0.07 (stage 2) dependent on severity of rA. the comparable relative reduction of DXr-bMD was-11.1%. the group of patients with minor disease activity (DAs 28>5.1) showed