SAT0289 Long-term effects of tnf-alpha inhibitors on bone mineral density and the incidence of vertebral fractures in patients with ankylosing spondylitis
Authors: K. Beek, M. van der Weijden, T. Rusman, W. Lems, C. van Denderen, M. Nurmohamed, I. van der Horst-Bruinsma
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> Ankylosing Spondylitis (AS) is not only characterised by pathological bone formation leading to ankylosis, but also by bone loss which may lead to vertebral fractures (VFx). TNF-alpha inhibitors (TNFi) have proven to be effective in blocking the inflammatory process. A few studies also showed an increase of Bone Mineral Density (BMD) in AS patients treated with TNFi <sup>1–3,</sup> however, the incidence of VFx after two years of treatment was increased.<sup>3–4</sup> <h3>Objectives</h3> To evaluate the long-term effect of TNFi on BMD and the incidence of VFx in patients with AS. <h3>Methods</h3> Consecutive TNFi naive AS patients (who fulfilled the Modified New York criteria) were included. Patients were recruited from the VUmc and Reade and were treated with TNFi for 4 years. BMD at hip and lumbar spine (LS) were measured at baseline and after 4 years. T-scores were categorised as 'normal BMD', 'osteopenia' and 'osteoporosis', based on the WHO osteoporosis criteria.<sup>5</sup> The incidence of VFx was determined by two observers using the Genant method.<sup>6</sup> <h3>Results</h3> In total, 107 AS patients with complete datasets (68.2% male) were included. The mean age was 42.6 years and the disease duration (time since diagnosis) was 11.0 years. The use of steroids or osteoporosis profylaxis varied respectively between 0.9% and 2.8%. At baseline 40.1% of the patients had a decreased BMD of the hip and 40.2% of the spine, of whom 27 patients (26%) had both a decreased hip BMD as well as a decreased lumbar BMD. The BMD of spine and hip improved after 4 years of TNFi treatment (table 1). In 13 patients (12.1%), 14 VFx were observed both at baseline and after 4 years of TNFi-treatment, 26 VFx were observed in 21 patients. After 4 years, 4 out of 21 patients with ≥1 VFx had a decreased BMD at hip and lumbar spine whereas the other 17 patients had a normal BMD. The majority of VFx was localised in the mid or lower thoracic spine. <i>Table 1</i> BMD measurement in spine and hip of 107 AS patients treated with TNFi. <h3>Conclusions</h3> The percentage of relatively young AS patients with a decreased BMD at baseline of the hip and lumbar spine was high (40%). After 4 years of TNFi-treatment, the BMD of the lumbar spine improved in 14.9% of the patients and of the hip in 8.3% of the patients. At baseline, 12% of the patients had vertebral fractures which increased to 21% after 4 years of treatment. A normal population of 1984 individuals above 50 years showed a prevalence of 8.9% osteoporotic spinal fractures.<sup>7</sup> Probably, the start of treatment with TNFi at an earlier stage of the disease might prevent the onset of fractures in AS. <h3>References</h3> [1] Visvanathan S, et al. Ann Rheum Dis2009. [2] Arends S, et al. Arthritis Res Ther2012. [3] van der Weijden, et al. J Reumatol2016. [4] Maas F, et al. ClinExpRheumatol2016. [5] Kanis JA, et al. J Bone MinerRes1994. [6] Genant HK, et al. J Bone MinerRes1993. [7] Lotters FJ, et al. Calcif Tissue Int2016. <h3>Disclosure of Interest</h3> None declared