Hip and lumbar spine DXA useful in diagnosing osteoporosis in patients with ankylosing spondylitis

   According to research by investigators at Case Western Reserve University in Cleveland, there is a correlation between T-scores of hip and lumbar spine in patients with ankylosing spondylitis (AS) with disease duration of >five years, suggesting that DXA of the hip and the lumbar spine are useful in diagnosing osteoporosis (OP) in patients with AS. 

   They identified 101 patients with AS (26.2% females; 25.2% African-Americans (AA). The mean age was 43.0 years (+/-13.7) in patients with normal bone mineral density (BMD) vs 47.8 years (+/-14.4) with OP and osteopenia (P=0.0867), and 40.5% of patients had syndesmophytes on lumbar x-ray. The prevalence of OP was 16.8%, osteopenia 36.6%, and 46.5% had normal BMD. There was moderate correlation between the lowest T-values of hip and lumbar spine (AP view), rho=0.59. The AA with AS had higher odds of having osteoporosis compared to whites; odds ratio [OR] 5.3, 95% confidence interval [CI], 1.03 to 26.84, P=0.045. AS patients with high CRP levels had higher odds of having OP (OR 4.1; 95% CI, 1.22 to 13.97, P=0.0226. There was no association between OP and age, sex, Bath AS disease activity index (BASDI), vitamin D levels, HLAB27 positivity, and ESR.

   The investigators noted that “elevated CRP level increases the risk of OP in patients with AS. African-Americans with AS are at higher risk of developing OP compared to whites.”