Hand bone loss in early undifferentiated arthritis: evaluating bone mineral density loss before the development of rheumatoid arthritis

Objectives: (1) To examine the change in regional bone mineral density (BMD), including the hands, and assess its role as a predictor of outcome in patients presenting with an early undifferentiated inflammatory arthritis; (2) to examine for associations with the changes in hand BMD. Methods: 74 patients with undifferentiated hand arthritis of less than 12 months' duration were examined at baseline and then at three, six, and 12 months follow up, including BMD measurement of the femoral neck, spine (L2-4), and the whole hands using dual energy absorptiometry (DXA). Results: During the study, 13 patients were diagnosed as having rheumatoid arthritis, 19 as having inflammatory non-rheumatoid joint disorders, and 42 as having non-inflammatory joint disorders. At the femoral neck and lumbar spine no significant bone loss was seen in any of the three subgroups. At the 12 months follow up the mean (95% confidence interval) hand BMD loss in the patients with rheumatoid arthritis was 24.27% (21.41 to 27.13); in the inflammatory non-rheumatoid group, 20.49% (21.33 to +0.35); and in the non-inflammatory joint disorder group, 20.87% (21.51 to 20.23). In a multivariate linear regression model (including age, rheumatoid factor, mean C reactive protein, mean HAQ score, and cumulative glucocorticoid dose), only mean C reactive protein (p < 0.001) and rheumatoid factor (p = 0.04) were independently associated with change in hand BMD during follow up. Conclusions: Hand DXA provides a very sensitive tool for measuring bone loss in early rheumatoid arthritis and may be useful in identifying patients at high risk of developing progressive disease. Further studies are needed to evaluate the role of hand bone loss as a prognostic factor and outcome measure in rheumatoid arthritis.