Weight-bearing physical activity, calcium intake, systemic glucocorticoids, chronic inflammation, and body constitution as determinants of lumbar andfemoral bone mineral in juvenile chronic arthritis

The associations between the lumbar and femoral bone mineral and several bo dy constitutional, lifestyle, and disease related variables were studied in ill children with juvenile chronic arthritis (JCA) by factor and multiple linear regression analyses. In addition to the measurement of bone mineral density (BMD), bone width and bone mineral volumetric density (BMDvol) were determined by dual-x-ray absorptiometry (DXA). Factor analysis of 13 expla natory variables yielded six non-correlatin g factors, named as body size, physical activity, calcium intake, glucocorticoids, disease duration, and d isease activity. These six factors were used as new variables to explain BM D, BMDvol, and bone width by multiple linear regression analyses. These sho wed body size, physical activity, and calcium intake as significant positiv e and disease activity and glucocorticoids as significant negative determin ants of BMD in JCA. The analyses revealed also considerable differences in the relationships between factors and BMDvol or bone width.