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Age-related variation in quantitative ultrasound at the tibia and prevalence of osteoporosis in native Chinese women.

This study investigated the variations in age-related speed of sound (SOS) at the tibia and prevalence of osteoporosis in native Chinese women, and establishment of a reference database by quantitative ultrasound. SOS at the right midtibia was measured using a quantitative ultrasound device (SoundScan 2000, Myriad Ultrasound Systems, Israel) in 1596 healthy Chinese women ranging from 12 years to 96 years of age. Healthy women were selected on the basis of (1). a detailed questionnaire about their medical history, (2). face to face questioning about their medical history, and (3). a physical examination. Women with a medical condition that required medication that affected bone metabolism or those who had had a pathologic or moderate traumatic fracture were excluded. We followed the diagnostic criteria provided by the instrument's manufacturer and equivalent to the WHO criteria (using the T-score cut-off that diagnoses 30% of the post-menopausal women aged >or =50 years with osteoporosis) as the diagnostic criteria for osteoporosis in this group of women. Data were analyzed in age groups divided by intervals of 5 years. The peak SOS at the tibia of 3991+/-68 m s(-1) (mean+/-SD) occurred in the 35-39 year age group and the T-score precision was 0.99 T-score units. The SOS value increased with age up to 34 years of age and then declined with age after 40 years of age with the rate of decrease at 9.68 m s(-1) per year. The curve representing the SOS change according to age is best fitted by the regression analysis of cubic model, and the cubic equation for SOS=3383+39.9 (age)-0.78 (age)(2)+0.0039 (age)(3) (R(2)=0.505, p=0.000). The T-score cut-off that diagnoses 30% of the post-menopausal women (n=559, mean age 63.2+/-8.97 years) aged >or=50 years with osteoporosis was SOS<or=3733 m s(-1), T-score<or=-3.8. In the 40-49, 50-59, 60-69 and 70-79 years age groups and the group aged >or=80 years, the prevalences of osteoporosis detected using equivalent to the WHO criteria were 0.39%, 9.27%, 30.3%, 58.4% and 69.0%, respectively. The prevalences detected following the manufacturer's diagnostic criteria (cut-off value: SOS<or=3800 m s(-1), T-score<or=-2.0) were 3.14%, 20.5%, 53.2%, 78.8% and 89.7%, respectively. There were significant differences in the prevalence between the diagnostic criteria in the various age groups (p=0.000-0.002). In 769 women from 40 years to 59 years of age, the mean SOS was significantly higher in pre-menopausal women (n=500) than in post-menopausal women (n=269) (3977+/-89 vs 3881+/-118 m s(-1), p=0.000). The prevalence of osteoporosis in these women was 0.40% in pre-menopausal women, 8.92% in post-menopausal women, respectively. There were significant differences in prevalence of osteoporosis between the two groups of pre- and post-menopausal women (p=0.000). In conclusion, SOS at tibia can provided useful information about bone status in the normative population of native Chinese women for determination of osteoporosis. The reference database based on these data will be appropriate for the diagnosis of osteoporosis by tibial quantitative ultrasound in native Chinese women.