AB0356 COMPARISION FOREARM BONE MINERAL DENSITY BETWEEN LUMBAR SPINE AND HIP: A USEFUL TOOL TO SCREEN OSTEOPOROSIS IN FEMALE PATIENTS WITH RHEUMATOID ARTHRITIS
Authors: Yu Wang, Zhuoli Zhang
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background</h3> DXA is widely used in clinical practise in BMD measurement of osteoporosis. Forearm and axial BMD is the most common site to define in clinical practise. However, the relationship between forearm and axial BMD is not confirmed in RA patients. <h3>Objectives</h3> To compare the forearm (bone mineral density) BMD between lumbar spine and left hip BMD by dual-energy X-ray abosorptionmetry (DXA), and explore the diagnostic value of the forearm BMD in rheumatoid arthritis (RA) patients. <h3>Methods</h3> In the study, 200 female patients with established RA underwent DXA of the lumber, left hip and non-superiority forearm DXA at the same time. We compared BMD at different sites, and the diagnostic cut-off value of abnormal axial BMD by forearm BMD was explored. Data analysis was performed by independent-sample <i>t</i> test and Pearson's correlation test. The area under the receiver operating characteristic curve (AUC) and calibration of predictions were assessed. Sensitivity and specificity were calculated to determine the correlation between cases of osteoporosis detected by the axial DXA scan and forearm. <h3>Results</h3> (1) The mean age of the 200 female patients was (55.9±13.8) years. Twenty (10.0%) patients had the fragility fracture history. Based on their axial DXA data and fracture history, 30 (15.0%) patients had normal BMD (T score≥-1.0), 170 (85.0%) patients had abnormal BMD. The mean forearm BMD was (0.35±0.13) g/cm2, and T score was -2.3±1.9. (2) Compared with abnormal axial BMD group, forearm BMD in normal axial group was significantly decreased [(0.33±0.13) g/cm2 vs (0.44±0.06) g/cm2, t=4.29, P&lt;0.01], forearm T score was also significantly decreased [(-2.6±1.9) vs (-0.71±0.9), t=4.35, P&lt;0.01]. T score of the forearm BMD was positively correlated with axial BMD T score, both at lumber and left hip respectively (r=0.488, 0.543, P&lt;0.01). After correction by age, T score of the forearm remained positively correlated with axial T score by partial correlation analysis (Pearson partial vertebral r=0.46, P&lt;0.001; left hip r=0.502, P&lt;0.001). (3) The area under the ROC curve for diagnosis of lumber and hip osteoporosis were 0.757 (95%CI: 0.638, 0.876) and 0.615(95%CI: 0.481,0.749) separately. (4) The sensitivity and specificity for identifying osteoporosis in lumber were 86.5% and 50.1% respectively when the T-score threshold of forearm was defined as -3.52; however, the sensitivity and the specificity for identifying osteoporosis at left hip were 66.2% and 76.2% when T score threshold of forearm was defined as -2.5. <h3>Conclusion</h3> Our study has confirmed that DXA measurement performed of forearm analysis is capable of screening osteoporosis defined by axial BMD in female RA patients. <h3>References</h3> [1] Siris ES, Adler R, Bilezikian J, et al. The clinical diagnosis of osteoporosis: a position statement from the National Bone Health Alliance Working Group[J]. Osteoporos Int,2014,25(5):1439-1443. DOI: 10.1007/s00198-014-2655-z. [2] Hangartner TN, Warner S, Braillon P, Jankowski L, Shepherd J. The Official Positions of the International Society for Clinical Densitometry: acquisition of dual-energy X-ray absorptiometry body composition and considerations regarding analysis and repeatability of measures[J]. J Clin Densitom. 2013. 16(4): 520-536. DOI: 10.1016/j.jocd.2013.08.007 [3] Kilic G, Ozgocmen S. Hand bone mass in rheumatoid arthritis: A review of the literature[J]. World J Orthop. 2015. 6(1): 106-116.DOI: 10.5312/wjo.v6.i1.106 <h3>Acknowledgement</h3> none <h3>Disclosure of Interests</h3> None declared