Is hand bone mineral density a marker for hand function in patients with established rheumatoid arthritis? The correlation among bone mineral density of the hand, radiological findings and hand function.

The objective of this study is to assess the role of hand bone mineral density (BMD) as a prospective marker for hand function and the correlation of hand BMD with X-ray findings and hand functioning in patients with established rheumatoid arthritis (RA). Eighty-three female patients diagnosed with RA were enrolled. All BMD measurements were performed on both hands. The radiological evaluation was conducted according to the van der Heijde modification of the Sharp method (Sharp/van der Heijde). Duruöz Hand Index (DHI) was used to establish the disability in the hands. Furthermore, handgrip strength (HGS), pinch strength (PS), lateral pinch (LP), tip-to-tip pinch (TTP) and three-fingered pinch (TFP) on both the dominant and the non-dominant hands was measured. A significant positive correlation between hand BMD and HGS as well as all PSs with p < 0.05 was observed, while no statistically significant relation was observed between BMD and DHI (p > 0.05). The hand BMD and the Sharp/van der Heijde scores were significantly in reverse correlation (p < 0.05). As for other DHI-related variants, HGS and PS and the total DHI scores were reversely correlated, while there was a positive significant association with radiological scores (p < 0.05). HGS and TTP were found significant (p < 0.05) as a result of a multivariant linear stepwise regression analysis among the sub-groups of DHI, HGS, LP, TTP, TFP and radiographic total scores. Our study demonstrated that a one-off hand BMD measurement failed to adequately indicate a loss in hand function as measured by DHI. Ultimately, HGS and TTP were shown to be the most effective indicators for measuring hand functions.