Comparison of three bone densitometry methods in osteoporotic women

Three techniques of bone mass measurement were evaluated in the diagnosis of postmenopausal osteoporosis; the overlap in the measurements and the capacity for discriminating was determined among 51 postmenopausal normal (mean age 66.6 +/- 8.4 years) and 42 postmenopausal osteoporotic women (mean age 68.5 +/- 7.5 years). All bone mass was evaluated by total body bone mineral content (BMCTB), density (BMDTB), ultrasound bone velocity (UBV) in proximal phalanxes 2-5 of the nondominant hand (UBV = mean value of all ultrasound measurements), and peripheral quantitative computed tomography of the nondominant forearm (pQCT). BMCTB, was found to be significantly better (P < 0.0001) for diagnosing postmenopausal osteoporosis than the other methods; both cortical and trabecular pQCT measurements were more discriminating than the corresponding UBV measurements (P < 0.001). T-score values in normals, subjects versus osteoporotic ones were BMCTB -1.15 +/- 0.79 versus -3.17 +/- 0.74; BMDTB -1.01 +/- 0.97 versus -3.28 +/- 0.81; UBV -1.51 +/- 1.02 versus -2.34 +/- 1.21; trabecular-pQCT -0.40 +/- 0.72 versus -1.57 +/- 0.37; cortical-pQCT -1.00 +/- 0.87 versus -2.67 +/- 0.53; and total-pQCT -0.65 +/- 1.01 versus -2.34 +/- 0.27, respectively. The overlap in values between the postmenopausal normal and postmenopausal osteoporotic groups was 50% with UBV, 6% with BMCTB, 9% with BMDTB, 25% with cortical pQCT, and 42% with trabecular pQCT. BMCTB, BMDTB, UBV, and pQCT correlated well with each other as measurements of bone mass, but BMCTB was more discriminating than the other measurements in the diagnosis of osteoporosis.