FRI0073 Changes of bone mineral density over 10 years in patients with early rheumatoid arthritis
Authors: L. Theander, M. Willim, J.Å. Nilsson, M. Karlsson, K. Åkesson, C. Turesson
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> Patients with Rheumatoid Arthritis (RA) have been shown to have an increased risk of osteoporosis and fractures. Most studies on RA and osteoporosis are cross-sectional. There are very few studies on changes in bone mineral density (BMD) over time. <h3>Objectives</h3> To study changes in BMD in men and women with early RA over a period of ten years. <h3>Methods</h3> An inception cohort of consecutive patients with early RA (n=233, symptom duration &lt;12 months), recruited 1995–2005, was investigated. Patients were followed according to a structured program, including dual-energy X-ray absorptiometry (DXA) of the left femoral neck and the lumbar spine (L2-L4) at inclusion and after 2, 5 and 10 years. Z-scores (standard deviations above or below the mean BMD for the given age and sex) were calculated using a cohort of healthy individuals from the same area as a reference population. The mean Z-score over the study period was estimated using mixed linear effect models. Changes in Z-scores between follow-up visits were analysed using the paired T-test. Data are presented as mean (95% confidence interval (CI)). <h3>Results</h3> At inclusion, 219 patients were examined with DXA. The corresponding numbers at 2, 5 and 10 years were 196, 172 and 121. Among those with baseline DXA data, mean age was 60 years, mean symptom duration 7.4 months and 70% were women. Men were older (mean age 63 vs 59 years) and more often treated with corticosteroids (49% vs 35%) than women at inclusion. The majority of men and women were on disease modifying anti-rheumatic drugs (86% vs 81%). More women were treated for osteoporosis (bisphosphonates and/or calcium and vitamin D) and of the women, 16% were on oestrogen at inclusion. At the femoral neck, the mean Z-score over 10 years of time was −0.07 (-0.22; 0.08) in women and −0.33 (-0.57; −0.08) in men. Men had significantly lower BMD at the femoral neck than expected by age at inclusion (estimated by the intercept Z-score value −0.35; 95% CI −0.61; −0.09), whereas there was no significant overall change in Z-score over time in men or women. At the lumbar spine, the mean Z-score for women was 0.06 (-0.10; 0.21) and for men −0.05 (-0.29; 0.19). There was a significant increase in Z-scores at the lumbar spine over time in both groups (change/year 0.04 (0.03; 0.05) in women and 0.02 (0.00; 0.05) in men). The paired comparisons of BMD at different follow-up visits are shown in table 1. In the femoral neck, Z-scores for men decreased significantly from inclusion to the 5 year follow-up visit. After 5 years, no further reduction was seen. Lumbar spine BMD Z-scores increased in both men and women over the study period. <h3>Conclusions</h3> In this study of patients with early RA, men had low femoral neck BMD at study start and kept losing bone mass during the first 5 years of follow up. Lumbar spine BMD Z-scores in both women and men increased significantly over the study period. Potential explanations for the low femoral neck BMD in men include exposures that may predispose to both RA and low BMD, such as smoking and low androgen levels. The increasing lumbar spine BMD could be due to more extensive anti-osteoporotic treatment compared to the reference population, and possibly more artefacts, such as extensive aortic calcification or degenerative spinal changes, in patients with RA. <h3>Disclosure of Interest</h3> None declared