SAT-LB088 Assessing Metacarpal Cortical Thickness as a Tool to Evaluate Bone Density Compared to DXA in Osteogenesis Imperfecta

Abstract OBJECTIVE: Dual-energy X-ray absorptiometry (DXA) is routinely used to assess areal bone mineral density (aBMD) and to monitor the response to therapy. However, the interpretation of aBMD as assessed by DXA can be limited by many factors in individuals with osteogenesis imperfecta (OI). In this study, we assessed the cortical thickness of the second metacarpal bone as an alternative measure of aBMD in individuals with OI who were enrolled in a multicenter natural history study of the Brittle Bone Disorders Consortium. MATERIALS AND METHODS: This was a cross sectional cohort study of patients with OI. The inclusion criteria were (1) a diagnosis of OI type I-IV (2) measurements of the metacarpal cortical thickness (MCT) of the non-dominant hand and aBMD of the lumbar spine (LS) by DXA during the same research visit within six months The exclusion criteria were aged > 19 years, spinal instrumentation, and incomplete data. The z-scores for MCT were calculated using previously published age-based standards and were compared with the LS aBMD z-scores assessed by DXA. RESULTS: Sixty four individuals met the criteria for enrollment in this analysis. Of these, 20 (31%) had OI type I, 25 (39%) had OI type III, and 19 (30%) had OI type IV. MCT positively correlated with LS aBMD (r = 0.68, p < 0.01) whereas the MCT and the LS aBMD z-scores showed no correlation (r = - 0.11, p= 0.38). The sensitivity of MCT to detect low aBMD defined as a LS aBMD z-score ≤-2.0 was 90% while the specificity was 31.5%. DISCUSSION: This is the first multi-center study to investigate the correlation between MCT and LS aBMD assessed by DXA in a large cohort of individuals with OI. We demonstrate that absolute values of MCT and LS aBMD show a strong positive correlation. The high sensitivity associated with using MCT to detect individuals with low LS aBMD allude to the fact that this may be used as a surrogate measurement for bone mineral density. However, further studies in a larger sample are needed to determine whether MCT can serve as a useful, cost-effective and readily available method for assessing aBMD in OI. Unless otherwise noted, all abstracts presented at ENDO are embargoed until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. Abstracts presented at a news conference are embargoed until the date and time of the news conference. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.