Soft tissue composition, axial bone mineral density, and grip strength in postmenopausal Turkish women with early rheumatoid arthritis: Is lean body mass a predictor of bone mineral density in rheumatoid arthritis?

Objective: To study bone mineral density and body composition in patients with early rheumatoid arthritis to determine the relationship of lean mass, fat mass and hand grip strength to bone mineral density.

Methods: Fifty-one female patients who fulfilled the American College of Rheumatology (ACR) for RA were recruited. Fifty-one (51) female RA patients, age matched female control subjects and 53 osteoporotic patients (WHO criteria) were included in the study. All subjects were at postmenopausal period. Early RA is defined as the disease duration <10 years. Whole body composition and BMD were estimated by DEXA (Norland XR-46). Hand grip strength was measured by JAMAR hand dynamometer. Body mass index (BMI) and anthropometric measures (skinfold thickness and waist-hip ratio) were also assessed.

Results: The mean age of patients and controls was 55.4 +/- 9.5, 56.9 +/- 7.4, and 55.2 +/- 7.6, respectively. There was no statistically significant difference in age, BMI, and years since menopause between RA patients, OP patients, and controls (p < 0.05). Bone mineral density of lumbar and femoral neck regions, total bone mineral density, and bone mineral content in RA patients were significantly lower than in controls but not in osteoporotic patients. Lean body mass was also significantly lower in RA patients than controls but not in osteoporotic patients. However, hand grip strength was significantly lower in RA patients than in osteoporotic patients and controls (p < 0.05). Total lean mass was correlated with body mass index, waist-hip ratio, femoral neck BMD, and total bone mineral content, total BMD in RA patients (p < 0.05). Grip strength was correlated with duration of disease (RA) and age negatively, and also correlated with total BMD in RA patients.

Conclusion: These results indicate that lean mass was associated with BMD. To preserve BMD, maintaining or increasing lean mass would appear to be an appropriate strategy for avoiding hip fracture and its complications.