DECREASED AXIAL BONE-MINERAL DENSITY IN PERIMENOPAUSAL WOMEN WITH RHEUMATOID-ARTHRITIS - A POPULATION-BASED STUDY

Objectives-Although periarticular osteoporosis is a well-recognised ph enomenon in rheumatoid arthritis (RA), there is considerable controver sy over whether RA is associated with more generalised osteoporosis. T he aetiology of this bone loss is probably multifactorial, including b oth life-style risk factors and disease-related determinants. Populati on-based studies on bone mineral density (BMD) in RA have not previous ly been conducted, and the purpose of the present cross-sectional popu lation-based study was to determine whether patients with RA are at an increased risk of having osteoporosis. Furthermore, the determinants of BMD in RA patients were investigated. Methods-BMD at the spine and femoral neck was measured in 143 women with RA. The control group cons isted of 1611 women with no disease or taking any drugs known to affec t bone metabolism. The study population was a random stratified sample from the Kuopio Osteoporosis Study, which included all perimenopausal women aged 47-56 years residing in Kuopio Province, Eastern Finland i n 1989 (n = 14 220). The mean age of the patients at the time of densi tometry was 53.7 years. Results-The mean (SD) spinal and femoral neck BMD was significantly lower in patients with RA compared with controls [spine: 1.067 (0.161) v 1.129 (0.157) g/cm2, p < 0.001; femoral neck: 0.851 (0.136) v 0.932 (0.123) g/cm2, p<0.001]. Analysis of variance s howed that at the spine the difference was significant only in patient s having corticosteroid treatment, whereas at the femoral neck patient s with non-steroid treatment also had significantly lower BMD. When co nfounding factors were corrected, no significant difference could be f ound between non-steroid and corticosteroid treated patients with RA, suggesting that the independent effect of corticosteroids on BMD is on ly minimal. Multiple regression analysis found age, weight and functio nal grade to be significant predictors of spinal BMD (R2 = 0.403, p < 0.001). In the femoral neck weight, cumulative corticosteroid dose and functional grade were significant predictors of BMD (R2 = 0.410, p < 0.001). Conclusions-RA is associated with generalised osteoporosis. Th e physical impairment and body weight are the major determinants of bo th spinal and femoral bone mass in RA patients. The cumulative cortico steroid dose was also a significant determinant of femoral neck BMD. H owever, the independent effect of corticosteroids is questionable beca use the use of corticosteroids may be an indicator of more severe dise ase.