BMD measurements and cross-calibration Femoral neck, total hip, and total lumbar spine BMD (gram per square centimeter) www.selleckchem.com/products/jq-ez-05-jqez5.html were measured using Hologic QDR 4,500-W densitometer (Hologic Inc, Bedford, MA) in the MrOS Study, the MrOS Hong Kong Study, and the Tobago Bone Health

Study and using Lunar Prodigy (GE, Madison, WI) in the Namwon Study. All BMD scans were conducted using standardized procedures following the manufacturer’s recommended protocols. All DXA operators in each study were trained and certified. Longitudinal quality control was performed daily with a spine phantom and showed no shifts or drifts in each study site. From 2002 to 2005, by the Musculoskeletal and Quantitative Imaging Research Group at the University of California, San Francisco (UCSF), cross-calibration studies were carried out using the Hologic spine, femur, and block phantoms for the scanners used in the MrOS Study (US sites; 2000), the MrOS Hong Kong Study (2002), and the Tobago Bone Health Study (2004). For this analysis, UCSF also carried out a cross-calibration procedure in 2008 using the same phantoms for the scanner of the Namwon Study. Since the sites included Lunar and Hologic scanners, BMD parameters were standardized (converted

to sBMD) according to the formula published by Hui et al. [23]. Corrections for any statistically significant differences across scanners were GDC-0973 mw then applied to participant spine, total hip, and femoral neck BMD values. BMD values for participants at the six US sites and Hong Kong sites, but not in Tobago or Korea, were also corrected for longitudinal shifts, based on Hologic spine phantom scanned during the visit on each Nabilone densitometer. Details on the cross-calibration procedure were as follows. Phantom scans were scanned five times each on the same day and were analyzed centrally by the same research assistant (MrOS, MrOS Hong Kong, Tobago) or locally (Korea) for each DXA scanner. To avoid edge effects, subregional analyses were used by UCSF to

analyze all block phantom scans. One MrOS US site was considered the reference site. The phantom BMD results were first converted to sBMD [23]. In order to derive the linearity of each machine, linear selleck kinase inhibitor regression was used in analyzing the block phantom results. The ratio between the study site and the reference site (reference site/measurement site) for sBMD was then calculated. ANOVA with a Dunnet test was applied to determine the mean sBMD difference between the study site and the reference site. If the sBMD for a study site was significantly different from the reference site, the ratio was used as the cross-calibration factors for each specific scan type. Otherwise, the cross-calibration factor was set to 1.