(A) Bone loss begins in the third decade of life in both sexes. The data are from the Epidemiological Follow-up Study cohort of the NHANES I, a nationally representative sample of noninstitutionalized civilians who were followed for a maximum of 22 years. A cohort of 2879 White males (1437 in the bone density subsample) aged 45 to 74 years at baseline (1971 to 1975) were observed through 1992[1]. (B) Age is a more critical determinant of fracture risk than bone mass in humans. Data are from a follow-up of 521 White females over an average of 6.5 years with repeated bone mass measurements at the radius. A total of 138 nonspinal fractures in 3388 person-years were detected, and the incident fractures were cross-classified by age and bone mass. The incidence of fracture was then fitted to a log-linear model in age and bone mass[2].
BMD: bone mineral density; NHANES: National Health and Nutrition Examination Survey.
References:
Looker AC, Wahner HW, Dunn WL, et al. Updated data on proximal femur bone mineral levels of US adults. Osteoporosis Int 1998; 8:468.
Hui SL, Slemenda CW, Johnston CC Jr. Age and bone mass as predictors of fracture in a prospective study. J Clin Invest 1988; 81:1804.