Bone mineral density measurements
Dual-energy X-ray absorptiometry (DXA) was used to determine bone mineral density (BMD). DXA measured the lumbar spine (L1–L4) in the anteroposterior (AP) projection and the three sites of the right and left hip (femoral neck, Ward’s triangle, and trochanter) using Lunar, DPX-L. The coefficient of variation (CV) for three sets of measurements was 1.0%.
Osteopenia was defined according to the classical WHO criteria, as a T score for the lumbar AP or femoral neck between -1 SD and -2.5 SD accordingly.
Osteoporosis was defined as the BMD T score on DXA at the lumbar spine or femoral neck that is less than or equal to -2.5 SD for postmenopausal women and aged over 50 years men. For premenopausal women and those aged below 50 years men, it was defined as a BMD Z score on DXA at the lumbar spine or femoral neck less than -2 SD or equal.