Bone mineral density by digital X-ray radiogrammetry is strongly decreased and associated with joint destruction in long-standing rheumatoid arthritis: a cross-sectional study.
BACKGROUND
The aims were to explore bone mineral density (BMD) by digital X-ray radiogrammetry (DXR) in postmenopausal women with long-lasting rheumatoid arthritis (RA) in relation to dual x-ray absorptiometry (DXA)-BMD, joint destruction by conventional radiographs and disease related variables in a cross-sectional study.


METHODS
Seventy-five postmenopausal women with RA were examined by DXA measuring DXA-BMD of the forearm, total hip and lumbar spine, by scoring joint destruction on plain radiographs by the method of Larsen and by DXR-BMD in metacarpals two to four. The DXR-BMD results of the RA women were compared with an age and sex-matched reference database. A function of DXR-BMD in relation to age and disease duration was created. Associations were investigated by bivariate and multiple linear regression analyses.


RESULTS
DXR-BMD was strongly decreased in RA patients compared to the reference database (p < 0.001). Calculations showed that DXR-BMD was not markedly influenced the first years after diagnosis of RA, but between approximately 5-10 years of disease there was a steep decline in DXR-BMD which subsequently levelled off. In multiple regression analyses disease duration, CRP and DXR-BMD were independent variables associated with Larsen score (R2= 0.64). Larsen score and BMD forearm were independent determinants of DXR-BMD (R2 = 0.79).


CONCLUSIONS
DXR-BMD was strongly reduced and associated with both Larsen score and DXA-BMD forearm in these postmenopausal women with RA implying that DXR-BMD is a technique that reflects both the erosive process and bone loss adjacent to affected joints.
Department of Rheumatology and Inflammation Research, Sahlgrenska Academy at University of Gothenburg, Centre for Bone and Arthritis Research, Box 480, S-405 30 Gothenburg, Sweden. helena.forsblad@vgregion.se
Helena
H
Forsblad-d'Elia
Hans
H
Carlsten
D015502:Absorptiometry, Photon / Q000379:methods* / Q000592:standards; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000000981:diagnostic imaging* / Q000378:metabolism* / Q000473:pathology; D001175:Arthrography / Q000379:methods* / Q000592:standards*; D015519:Bone Density / Q000502:physiology*; D050824:Carpal Joints / Q000000981:diagnostic imaging / Q000473:pathology; D003430:Cross-Sectional Studies; D005260:Female; D005384:Finger Joint / Q000000981:diagnostic imaging / Q000473:pathology; D033023:Foot Joints / Q000000981:diagnostic imaging / Q000473:pathology; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000473:pathology; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000473:pathology; D008662:Metacarpophalangeal Joint / Q000000981:diagnostic imaging / Q000473:pathology; D008875:Middle Aged; D017698:Postmenopause / Q000502:physiology; D014955:Wrist Joint / Q000000981:diagnostic imaging / Q000473:pathology