Anti-tumor necrosis factor therapy increased spine and femoral neck bone mineral density of patients with active ankylosing spondylitis with low bone mineral density

Abstract

Objective. To evaluate the effect of anti-tumor necrosis factor (TNF) therapy on bone mineral density (BMD) in patients with active ankylosing spondylitis (AS) with low BMD. Methods. Eighty-nine patients with active AS with low BMD were randomly divided into either a study group or a control group. The study group received etanercept (50 mg/week) or adalimumab (40 mg/2 week) subcutaneously for 1 year. BMD of lumbar spine and femoral neck was measured by dual energy X-ray absorptiometry, and bone turnover markers serum C telopeptide of type-I collagen (sCTX) and serum procollagen type-I N propeptide (PINP) were detected by ELISA at baseline and at end of study. Results. After 1 year, compared with baseline, there was a significant increase in spine and femoral neck BMD by a mean ± SD of 14.9% ± 15.6% (p < 0.0001) and 4.7% ± 7.9% (p < 0.0001) in the study group. In the control group, there was a significant decrease in spine and femoral neck BMD by a mean ± SD of -8.6% ± 9.7% (p < 0.0001) and -9.8% ± 11.5% (p < 0.0001). Compared with baseline, sCTX was significantly decreased in the study group (-40% at 1 yr, p < 0.0001), but bone-specific alkaline phosphatase and PINP increased (45.6%, p < 0.0001 and 30.8%, p < 0.0001, respectively). Conclusion. In patients with active AS with low BMD, the spine and femoral neck BMD increased after anti-TNF therapy for 1 year, and it was accompanied by a significant decrease in bone resorption markers and an increase in bone formation markers.