2646-P: Optimizing DXA Imaging in Obese Populations: Lessons from the COURAGE Study

Introduction and Objective: Including body composition endpoints by DXA in obesity clinical trials is an FDA requirement and minimization of data loss due to poor-quality images is critical. To ensure high-quality DXA for a primary endpoint we introduced two rules in a phase 2 study: 1) measurable baseline scan as an eligibility criterion; 2) allow for one DXA repeat. We aim to evaluate the DXA success rate following this strategy for planning future studies and to analyze the reasons for image failure. Methods: We enrolled 981 subjects across 57 USA centers. Subjects underwent whole-body DXA imaging at baseline, week 16, and week 26. Images were read centrally by a blinded core laboratory that evaluated image quality and, if adequate, measured total fat and lean mass (successful DXA). The cause of each failed scan was classified into 6 categories (Table). Results: At baseline, 8.6% of participants had an initial scan fail requiring repeat imaging, mostly due to missing anatomy. At week 16 and week 26, 865 (86.3%) and 791 (80.6%) participants underwent DXA, respectively. Repeat image rates were 8.9% at week 16 and 5.6% at week 26 (Table). In the follow-up DXA, the reasons for repeat were inconsistent positioning and scan mode changes compared to baseline. Conclusion: Repeat imaging was successful in reducing the overall scan failure rate and should only be repeated once. In obesity studies using DXA imaging as a primary endpoint, the DXA success rate should be considered when estimating sample size. Disclosure A. Vavere: Employee; Current; Regeneron Pharmaceuticals Inc. Employee; Ended; AstraZeneca. Stock/Shareholder; Current; AstraZeneca, Regeneron Pharmaceuticals Inc. T.A. Swanson: None. J. Lighter: None. O. Mosenzon: Employee; Current; Regeneron Pharmaceuticals Inc. Stock/Shareholder; Current; Regeneron Pharmaceuticals Inc. R.A. Calle: Employee; Current; Regeneron Pharmaceuticals Inc. Stock/Shareholder; Current; Regeneron Pharmaceuticals Inc. Stock/Shareholder; Ended; Pfizer Inc. J.G. Raya: Employee; Current; Regeneron Pharmaceuticals Inc. Stock/Shareholder; Current; Regeneron Pharmaceuticals Inc.