The change of bone mineral density according to treatment agents in patients with ankylosing spondylitis

Objectives: The aim was to access the effects of treatment on bone mineral density (BMD) by treatment agents in patients with ankylosing spondylitis (AS). Methods: We analyzed clinical characteristics of 90 AS patients. Erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and x-ray of lumbar spine (L-spine) and sacroiliac joint were included in the baseline assessment. The BMDs of right femur and L-spine were measured annually using dual x-ray absorptiometry (DXA). The patients were divided into one of the following four groups by agents exposed for the follow-up period: conventional treatment, bisphosphonate, anti-TNF-α agent or bisphosphonate. +. anti-TNF-α agent. We evaluated the changes of BMD according to treatment groups. Results: The average age of disease onset was 30 years and the mean disease duration was 8.2 years. The patients who were assigned to the groups of conventional treatment, bisphosphonate, anti-TNF-α agents and bisphosphonate. +. anti-TNF-α agents were 40, 20, 19 and 11. BMDs values of both L-spine and femur showed tendencies to the most increase in the group treated with concurrent bisphosphonate and anti-TNF-α agent. However, the change of BMD by treatment agents was significant different only in trochanter (P= 0.001). In patients without syndesmophyte, there was significant difference of BMD change in both L-spine and total proximal femur (P= 0.001, 0.004). The BMD change of trochanter was correlated with the reductions of ESR and CRP (r= 0.239, P= 0.035 and r= 0.233, P= 0.040). Conclusions: The BMDs of AS patients increased more by the treatment of concurrent bisphosphonate and anti-TNF-α agents. The gain of bone mass was associated with the reduction of inflammation.