Does a loss in hand bone mineral density increase risk of future bone erosion?

This paper studies whether a loss of hand bone mineral density (BMD, the amount of calcium and other minerals in an area of bone) in the first 6 months of treatment increases the risk of bone erosions at 12 months for patients with rheumatoid arthritis.

Treatment of rheumatoid arthritis in its earlier stages is more effective with less bone erosion at 12 months. However, some patients still have progressive bone erosion. Patients at risk of bone erosion can be identified to be given more intensive treatment. This can be achieved by measuring hand bone mineral density loss, as this is associated with joint destruction. The authors used dual x-ray absorptometry instead of previously used digital x-ray radiogrammetry to measure bone mineral density as it is more available in a clinical setting. 

106 patients with recent onset of rheumatoid arthritis were included in the study. Patients had not previously taken disease-modifying antirheumatic drugs (DMARDs).They were treated with a combination of methotrexate(Rheumatrex,Trexall), sulphasalazine(Salazopyrin) and hydroxychloroquine(Plaquenil).

For each patient, the Disease Activity Score (measures activity of rheumatoid arthritis) was calculated. Hand bone mineral density was determined using dual x-ray absorptometry at the start of the study and after 6 months. X-rays of hands and feet were obtained.

Based on change in bone mineral density from the start of the study to 6 months, patients were divided into a bone loss group (50 patients) and a no bone loss group (56 patients). Erosion scores of patients were compared between the 2 groups. 48% of patients in bone loss group had 1 or more erosions at 12 months compared with 25% of patients in no bone loss group. Patients with a loss in bone mineral density were also at a higher risk of erosion progression with 34% affected compared with 16% in no loss group. 

The authors concluded that bone mineral density loss may be useful in identifying erosion progress in patients who initially did not have erosive disease but are at risk for developing the disease.

This was a small and short study, and a longer study could confirm the results.