MoTrPAC Supplemental Funding for Miller

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Research Strategy: The overarching purpose of this work will be to perform preliminary work required to harmonize dual-energy X-ray absorptiometry (DXA) data collected using diverse systems across MoTrPAC study sites. The manufacture scanners (e.g., makes and models) and software versions are different across sites. Because of proprietary techniques and algorithms used, the calculated measurements can vary across machines. Standardization and cross calibration are important to understand whether differences between measurements exceed the least significant change or smallest detectable difference. For future use of these data, it is critical to understand whether differences between sites indicate an actual difference between assessments, or whether differences between assessments fall within the expected measurement error. To obtain consistent DXA scan results, quality control (QC) needs to be performed before these data can be further used for analysis. A few studies have developed conversion equations between DXA instruments. However, these studies did not use the same instruments used in MoTrPAC and/or the equations were generated based on small datasets. We propose to do more validation work by analyzing several external datasets to evaluate whether the calibration can be performed in our own dataset. Besides the in vivo (i.e., comparison of cohorts) approach, we will also use in vitro (i.e., comparison of phantoms) approach to detect the inter-instrument difference. Inter-instrument calibration will be carried out for 3 clinical sites.