Validation of the use of the hand for estimating bone mineral density in other skeletal sites by DXA in healthy and osteoarthritic women.

Abstract

Hand bone mineral density (BMD) by DXA has mainly been used to assess bone loss in rheumatoid arthritis patients. Its use in healthy subjects is limited. The following study was conducted to determine if measurements of hand BMD could estimate ones risk of osteoporosis and predict BMD in other skeletal sites. Subjects consisted of 134 Caucasian females (57-88 yr, 46 with self-reported osteoarthritis and the rest healthy). BMD was measured in the hand, forearm, hip, spine, and total body with the Lunar DPX-MD instrument. Subjects were divided into those with osteoarthritis (OA) and those without and were examined separately, as well as together. Hand BMD correlated significantly with all skeletal sites for the whole population and for each group. Pearson r for the whole population ranged from 0.56 in the lumbar spine to 0.82 in the forearm. Subjects with OA had higher correlations for most sites. Subjects' T-scores, derived from the reference population of young normal adult women, for hip, spine, forearm, and whole body correlated highly with hand BMD. To test how accurately hand BMD could predict BMD in other skeletal sites, we generated regression models from three-fourth of our subjects (n = 102). Based on the resulting regression equations and measured hand BMD, we calculated the predicted values of the BMD in all other skeletal sites for the remaining one-fourth of the subjects (n = 32). The predictive mean square errors, calculated from the observed and predicted values for each skeletal site, were small and below the cutoff values in F-distribution. In conclusion, hand BMD has a potential to establish one's risk for osteoporosis as well as reasonably accurately predict BMD in other skeletal sites. The hand BMD measurement in general, whether a part of DXA or as a separate instrument, might have a potential to be used for mass screening and in prospective studies to determine risk of fractures.