Rheumatoid Arthritis: Body Composition, Bone Loss, and Mortality

Early rheumatoid arthritis (RA) patients (disease duration ≤1 year, n=165) were recruited 1995-2001 and followed systematically clinically and with dual energy X-ray absorptiometry (DXA) over 2 years and compared to age- and gender-matched controls.
Baseline arm and leg lean mass were decreased in RA patients in both genders and body mass index and truncal fat distribution were increased in female RA patients.
After 2 years, all lean mass measurements decreased in controls and all fat mass measurements increased. Changes in RA patients were overall less pronounced than in controls.
Mean baseline bone mineral density (BMD) in lumbar spine and femoral neck were similar to the age- and gender-matched population and unchanged after 2 years. In multivariate analyses burden of disability (Area Under the Curve for HAQ) predicted individual changes in BMD in lumbar spine, burden of disease activity (AUC for DAS28) individual changes in BMD in femoral neck, whereas use of corticosteroids did not.
A prevalent RA cohort, recruited and systematically evaluated, clinically and radiographically, in 1978 (n=152), was studied to assess digital X-ray radiogrammetry (DXR) as a predictor of mortality. After 30 years the SMR was 3.39 (95% CI: 2.79, 3.98). Significant mortality predictors in age- and gender-adjusted Cox regression models were ESR, Steinbrocker functional classes, DXR and physician’s global assessment.
In conclusion, lean and fat mass, but not BMD in RA patients are altered already at diagnosis, partly associated with disease activity and relatively stable after 2-years. Hand DXR-BMD is a promising long-term predictor in RA.