Background Osteoporosis is a common complication of ankylosing spondylitis (AS); but the etiology of osteoporosis has not yet been completely clarified. It is thougt that the immobilization, local proinflammatory cytokines, genetic factors, non-steroidal antiinflammatory drugs (NSAIDs) and glucocorticoids used for treatment are the major causative factors of osteoporosis. It was reported that in patients with AS, the high disease activity was releated with the alterations in vitamin D metabolism and increased bone resorption.
Objectives The relationship among bone turnover markers, Vitamin D levels, disease activity, functional status and quality of life in patients with AS were investigated in this study.
Methods One hundred patients (69 males, 39 females; mean age 40,74±9,81 years) were diagnosed as AS according to modified New-York criteria were enrolled. In addition to the routine blood and urine tests, serum 25-(OH)D3, serum 1,25-(OH)D3, bone turnover markers (osteocalcin for formation and and serum C-terminal telopeptide (CTX) for resorption), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) levels of all participants were also measured. Anterior–posterior and lateral thoracic and lumbosacral radiography was performed on all participants and Bath Ankylosing Spondylitis Radiology Index (BASRI) was calculated. The disease activity was evaluated by Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and two AS disease activity scores (ASDAS) including the CRP and ESR, functional status by Bath Ankylosing Spondylitis Functional Index (BASFI), mobility by Bath Ankylosing Spondylitis Metrology Index (BASMI), quality of life with Ankylosing Spondylitis Quality of life Scale (AsQL).
Results The mean BASDAI, BASFI, ASDAS-ESR, ASDAS-CRP, AsQL, BASMI, BASRI were 2,04±1,91, 1,82±1,97, 2,11±0,77, 1,99±0,85, 5,27±5,86, 7,29±2,35 respectively. The mean 25-(OH)D3, osteocalcin, CTX values were 13,76±9,08, 23,36±7,26, 0,40±0,17 repesctively.
The present study didn't show any correlation between both serum D3 levels, osteocalcin levels and BASDAI, BASFI, ASDAS-ESR, ASDAS-CRP, AsQL, BASMI and BASRI (p>0.05). We couldn't find any correlation between CTX and BASDAI, BASFI, ASDAS-ESR, ASDAS-CRP, and BASMI (p>0.05). There were negative correlation between CTX and AsQL (p: 0.019, r: -0.234) and positive correlation between CTX and BASRI scores (p:0.002, r: 0.304).
Conclusions Our study showed that CTX as bone resorption marker was correlated with radiological score and quality of life in patients with AS.
Mermerci Baskan B, Pekin Dogan Y, Sivas F, Bodur H, Ozoran K. The relation between osteoporosis and vitamin D levels and disease activity in ankylosing spondylitis. Rheumatol Int. 2010;30(3):375–381
Arends S, Spoorenberg A, Bruyn GA, Houtman PM, Leijsma MK, Kallenberg CG, Brouwer E, van der Veer E: The relation between bone mineral density, bone turnover markers, and vitamin D status in ankylosing spondylitis patients with active disease: a cross-sectional analysis. Osteoporos Int 2011, 22:1431-1439.
Disclosure of Interest : None declared