Background Ankylosing spondylitis (AS) is characterized by chronic inflammation often leading to ankylosis of the spine, but also by a decrease of bone mineral density (BMD) and high prevalence of vertebral fractures (VF). Treatment with TNF blocking agents decreases inflammation and has shown to be effective in increasing BMD, but its effect on bone quality is not fully elucidated.
Objectives To study the effects of etanercept (TNF-blocker) on BMD and vertebral fractures in AS patients after two years of treatment. Additionally, changes in markers of bone turnover (CTXI, CTXII, RANKL, OPG, Osteocalcin) and radiological progression, including the thoracic spine, were studied during treatment with etanercept.
Methods Consecutive patients with active AS, treated with etanercept for two years, were included. BMD lumbar spine and hips was measured at baseline and after two years, as well as the radiological damage (mSASSS, including thoracic spine), vertebral fractures (Genant method) and change in bone-markers.
Results Forty-nine AS patients were included (Table). After two years of etanercept, hip BMD raised with 2.2% (p=0.014) and lumbar spine BMD with 7.0% (p<0.001). The BASDAI decreased significantly (p<0.001) as well as CRP and ESR (p<0.001). Despite etanercept therapy, the number of patients with vertebral fractures more than doubled (from 6 to 15 patients, p=0.004) as well as the severity. Also the radiological damage mSASSS+ThSpine increased significantly over time (from 12.1 to 18.5, p<0.001). No significant change in bone-markers was found during treatment.
Conclusions This prospective longitudinal observational cohort study in AS patients showed that after two years etanercept treatment, BMD of the hip and spine increased significantly. However, the number and severity of vertebral fractures increased, as well as the radiological progression, including the thoracic spine. Thus, the favourable effect of etanercept on BMD in AS is accompanied by unfavourable outcomes on vertebral fractures and radiological damage.
Acknowledgements This is an investigator initiated cohort study financed with an unrestricted Grant of Pfizer
Disclosure of Interest None declared