Racial/ethnic differences in bone mineral density among older women

The epidemiologic information regarding international differences in bone mineral density (BMD) in women is currently insufficient. We compared BMD in older women across five racial/ethnic groups in four countries. The femoral neck, total hip, and lumbar spine BMD were measured in women (aged 65–74 years) from the Study of Osteoporotic Fractures (SOF) (5,035 Caucasian women and 256 African American women in the US), the Tobago Women’s Health Study (116 Afro-Caribbean women), the Ms Os Hong Kong Study (794 Hong Kong Chinese women) and the Namwon Study (1,377 South Korean women). BMD was corrected according to the cross-site calibration results for all scanners. When compared with US Caucasian women, the age adjusted mean BMD measurements at the hip sites were 21–31 % higher among Tobago Afro-Caribbean women and 13–23 % higher among African American women. The total hip and spine BMD values were 4–5 % lower among Hong Kong Chinese women and 4–7 % lower among South Korean women compared to US Caucasians. The femoral neck BMD was similar in Hong Kong Chinese women, but higher among South Korean women compared to US Caucasians. Current/past estrogen use was a significant contributing factor to the difference in BMD between US versus non-US women. Differences in body weight partially explained the difference in BMD between Asian versus non-Asian women. These findings show substantial racial/ethnic differences in BMD even within African or Asian origin individuals, and highlight the contributing role of body weight and estrogen use to the geographic and racial/ethnic variation in BMD.     

Evolution of spinal bone loss and biochemical markers of bone remodeling after menopause in normal women

The main objective of this study was to describe longitudinal patterns of spinal bone loss in normal women who undergo a natural menopause. The second objective was to determine if a proportion of women suffer excessively rapid postmenopausal bone loss from the spine. If this was the case it was the aim to devise a means of predicting the women at excess risk; but if all women lost bone at similar rates, the aim was to document changing loss rates over the first 5–8 postmenopausal years. Responding women in six suburban general practices recalled for cervical smears who had their last menstrual period 9–36 months previously were invited to participate in a longitudinal study of bone loss and the biochemical markers plasma osteocalcin and urinary hydroxyproline. Sixty-four subjects agreed to participate, a response rate of 80%. In the ensuing 5 years, six received hormone replacement therapy and are not reported on. The main outcome measures were rates of spinal bone loss over 5 years, measured by dual photon absorptiometry, and radial bone loss over the first 2 years measured to quantitative computed tomography. Spinal bone loss was similar between individuals, with 94% of the variability in the data being accounted for by a statistical model that assumed parallel rates of bone loss. A less restrictive model allowing women to have different rates of spinal bone loss accounted for 12% more of the remaining variance in the data than the previous model. However, rates of radial bone loss were more dissimilar between women than rates of spinal loss. The results of the biochemical data collected serially showed that the plasma osteocalcin rose slowly to a plateau at 5 years postmenopause; in contrast, the hydroxyproline fell progressively with time over the whole period of study. These results were interpreted as being consistent with diminishing rates of bone destruction which gradually reequilibrated with bone formation as time passed after menopause.     

Smoking and bone loss among postmenopausal women.

We examined the effect of smoking on bone mineral density (BMD), rates of bone loss, and fractional whole-body retention of 47Ca in healthy postmenopausal women enrolled in a 2-year calcium supplementation trial. Bone density was measured by single- and dual-photon absorptiometry. BMD of the radius at the study baseline was inversely related to pack-years of exposure when controlled for body mass index and years since menopause (partial r = -0.18, p = 0.05, n = 125). The adjusted mean (+/- SD) annualized rate of bone change from the radius was greater among smokers than nonsmokers (-0.914 +/- 2.624%/year, n = 34, versus 0.004 +/- 2.568%/year, n = 278, respectively; p = 0.05). Similar trends were observed at the femoral neck, os calcis, and spine. Rates were were adjusted for caffeine intake, alcohol use, supplement type, and, at the spine only, menopausal status. At entry into the trial higher serum levels of alkaline phosphatase and lower levels of total and ionized calcium were found in smokers compared to nonsmokers. These differences did not persist with supplementation. In 44 women studied fractional 47Ca retention was lower in the 8 smokers than the 36 nonsmokers (16.6 versus 19.1%, respectively; p = 0.03). These results demonstrate an increased rate of bone loss at the radius after menopause and suggest that smoking is associated with decreased calcium absorption.     

Cyclical changes of vertebral body heights and bone loss in healthy women after menopause

Annual changes in vertebral body heights (VHs) and lumbar bone mineral density (LBMD) were evaluated in 120 healthy pre- and post-menopausal women aged 45–74 years. Subjects were divided into groups according to menstrual status and years since menopause (YSM).

Vertebral heights were evaluated, using radiological morphometry as the sum of anterior vertebral body heights (AVHs) from T4 to L5 at baseline and exactly 12 months later.

Results indicate that the sum of VHs is inversely correlated with advancing age, and the decrease in VHs is not a constant process over time but rather exhibits cyclical damping oscillations.

When log-linear trend of VH decrease was transformed into a constant considering annual percentage changes, the presence of a cyclical component of 7 years was evident. Employing a harmonic regression model, the cyclical component was also statistically significant on baseline data. The cyclical decrease of VHs corresponds to an analogous cyclical behavior of LBMD values.

These results suggest that a lack of estrogen acts as a synchronizer on bone remodeling, triggering a latent cyclical rhythm of bone loss, accompanied by cyclical bone microarchitecture deterioration and consequent vertebral body deformities, which after menopause persists throughout life. The existence of a chronobiological rhythm of bone loss and trabecular bone strength reduction at vertebral level after menopause, if confirmed, could have important clinical implications.     

Racial differences in femoral dimensions and their relation to hip fracture

White women have a higher rate of age-specific hip fractures than black women. Recently, femoral dimensions have been implicated in osteoporotic fractures. To study racial differences in femoral dimensions, dual X-ray absorptiometry scans were obtained for two similar groups of 50 white women and 50 black women. We measured the hip axis length (the distance from below the lateral aspect of the greater trochanter to the inner pelvic brim), the neck width and the neck/shaft angle on the scan print-out. The observer was masked to the race of the subject. The results were analyzed using the independentt-test and showed that the hip axis length and the neck width were significantly longer in the white women than in the black women (p values <0.05 and <0.02 respectively) but that the neck/shaft angle was not statistically different in the two groups. We conclude that femoral geometry differs among races. Whether this contributes to the lower risk of hip fracture in black women will require prospectively based studies.     

绝经妇女绝经后年限及年龄与骨量丢失率关系

目的探讨绝经后妇女的绝经年限及年龄与骨量丢失率关系。方法1999年5月-2003年4月,对已绝经的1467例妇女进行骨密度测定,并对不同绝经后妇女年龄、绝经年限与骨密度关系进行分析。结果1467例绝经后妇女中,以绝经1-5年期间和40-45岁时各部位骨密度作为基线值比较,绝经已超过35年或年龄大于80岁时各部位骨密度最低。其中按绝经年限腰椎、股骨颈、大转子、华氏三角区在绝经后6-10年间和超过35年时丢失速度最快;按年龄腰椎在56-65岁、股骨颈和华氏三角区在61-65岁、大转子在71-75岁及各部位大于80岁时丢失速度最快。结论绝经后妇女绝经年限及年龄增加,腰椎、股骨颈、粗隆、华氏三角区骨量丢失增加。绝经年限及年龄不同,各部位丢失速度不同。     

Different rates of forearm bone loss in healthy women with early or late menopause

The aim of this study was to evaluate whether healthy women with early or late menopause have different rates of age- and menopause-related bone loss, and whether premature menopause really represents a risk factor for osteopenia. Healthy women aged from 27 to 84 years (n=2204), with no history of fractures, were divided into two groups according to their age at menopause (AAM): group A with AAM43, and group B with AAM50 years. Bone mineral density (BMD) was measured in the distal non-dominant forearm by single-photon absorptiometry. Group B had a significantly lower average BMD than group A (group A, 0.430±0.074 g/cm²; group B, 0.419±0.081;p=0.003); however, the average age of group A was significantly lower, and weight and height were significantly higher. When women older than 50 years of age were divided into five age-matched subgroups, BMD was significantly lower in women with AAM43 years up to 60 years; after that age this difference disappeared and, in the oldest subgroups, BMD was significantly lower in group B than in group A. Independent variables such as age, AAM and body mass index (BMI) explain about 30% of the variation of BMD, using a multiple linear regression analysis. In both groups age and BMI weighted more than AAM in determining BMD. When BMD was plotted versus either chronological age or years since menopause, women with late menopause showed a significantly faster bone loss than those with early menopause. In conclusion, women with premature menopause have a lower peripheral bone mass than women with later menopause up to 60 years of age, but not later, when the risk of fractures is higher. This seems to be due to the fact that women with late menopause lose bone faster than those with early menopause.     

Correlations between periodontitis and loss of mandibular bone in relation to systemic bone changes in postmenopausal Japanese women

A new method of measuring mandibular alveolar bone mineral density (BMD) was applied to 40 postmenopausal Japanese women aged 50–69 years exhibiting minimal to mild periodontal diseases. Lumbar spine BMD was measured by dual X-ray absorptiometry (DXA) and calcaneus speed of sound (SOS) by quantitative ultrasound (QUS). There were age-related decreases of alveolar BMD, calcaneus SOS and vertebral BMD. There were significant correlations between two of the respective bone mass values. Correlations between clinical dental findings and bone mass data including alveolar BMD, SOS and lumbar spine BMD were investigated. Significant correlations were demonstrated between alveolar BMD and calcaneus SOS or vertebral BMD. Alveolar BMD showed significant correlation with clinical dental findings including periodontal pocket depth and mobility as well as calcaneus SOS and lumbar spine BMD. Using multivariate analysis combinations of univariate predictors, including deoxypyridinoline (DPD), significantly predicted attachment levels. The SOS value was useful combined with other predictors for predicting attachment level. It was concluded that the new method of evaluating alveolar BMD is useful to predict systemic bone mass and strength as well as dental clinical findings.     

Cyclical behavior of bone remodeling and bone loss in healthy women after menopause: results of a prospective study

Annual changes in lumbar bone mineral density (LBMD) and bone remodeling markers were measured in 238 healthy pre- and postmenopausal women, aged 45–74 years. The subjects were divided into groups according to their menstrual status and years since menopause. The results obtained indicate that bone loss is not a constant process over time but rather exhibits cyclical damping oscillations. When the log-linear trend of LBMD decrement was transformed into a constant by considering annual percentage changes, the presence of a cyclical component of 7 years was evident. By employing a harmonic regression model, the cyclical component was also statistically significant on baseline data. The cyclical behavior of LBMD decrement corresponded to an analogous behavior of the bone remodeling markers. These results suggest that a lack of estrogen acts as a synchronizer on bone remodeling by triggering a latent cyclical rhythm of bone loss that persists throughout life after menopause. The existence of a chronobiological rhythm of bone loss starting after menopause, if confirmed, could have important clinical implications.     

Bone loss in relation to menopause: a prospective study during 16 years

This prospective study evaluated bone loss in the peri- and postmenopausal period in 156 women followed from age 48 to 64 years. All women were premenopausal at the start of the study. Areal bone mineral density (g/cm(2)) was measured by single-photon absorptiometry (SPA) of the forearm at the 1 cm level (BMD 1 cm) and the 6 cm level (BMD 6 cm) every second year. Onset of menopause (MP) was determined according to the criteria of the World Health Organization (12 months of amenorrhea and elevated follicle-stimulating hormone). At the end of the study, 125 of 156 women (80%) remained. Bone mineral density (BMD) at age 48 years correlated with BMD at age 64 years within the respective region (r = 0.4-0.5, p < 0.001, respectively). There was no BMD loss in the premenopausal period. BMD loss was accelerated at menopause (MP) independent of chronological age. BMD loss was greater during the first 5 years following MP than during the following 6 years (BMD 1 cm 2.4% per year [1.0%-3.9%] vs. 0.4% per year [-0.3%-1.0%], p < 0.01). The quartile of women with late MP (>53.7 years) had greater bone loss during the first 5 years after MP than the quartile of women with early MP (<50.3 years) (p < 0.001). At age 64 years, BMD was no different when comparing the quartile of women with late MP vs. the quartile of women with early MP. Furthermore, there was no correlation between age at menopause and BMD at the age of 64. In summary, among women still menstruating at age 48 years, there was no measurable BMD loss in the premenopausal period. Independent of chronological age, BMD loss accelerated during MP. Rates of loss were highest in the early postmenopausal period. Independent of age at MP, premenopausal women with low age-specific BMD at age 48 years had an increased risk of sustaining low BMD at age 64 years also.     

Racial differences in mortality among those with CKD

Compared with white individuals, black individuals have a significantly higher risk for death in the general population but seem to have a survival advantage in the ESRD population. Data on the relationship of race to survival in early stages of chronic kidney disease (CKD) are inconsistent. This study evaluated racial differences in mortality among the adult participants of the Third National Health and Nutrition Examination Survey, a population-based survey of community-dwelling individuals. CKD was defined either by an estimated GFR < 60 ml/min per 1.73 m2 or by the presence of albuminuria, and this status was determined for 14,611 individuals, 2892 of whom were found to have CKD. Adjusting for age,gender, and race, risk for all-cause mortality among individuals with CKD was more than double that of individuals with normal renal function. In the subgroup with CKD, adjusting for age and gender,black individuals had a significantly higher risk for death, and this risk was modified by age;specifically, black individuals who were younger than 65 yr were 78% more likely to die than white individuals, whereas no significant differences in mortality were observed among individuals who were > or = 65 yr of age. Further adjustment for cardiovascular risk factors and CKD stage did not materially change the results, but the hazard ratios were significantly attenuated after adjustment for socioeconomic factors. In conclusion, these data demonstrate racial/ethnic disparities in mortality among individuals with CKD. This higher risk for death in early stages of CKD may explain the apparent survival advantage observed among black individuals who live long enough to reach stage 5 CKD.     

Long-term precision of bone loss rate measurements among postmenopausal women

Summary Repeated measurements of bone mineral content can indicate the rate of bone loss among postmenopausal women. The clinical utility of such loss rate measurements will depend upon the long-term precision of the measurements. We have analyzed the precision of appendicular bone measurements among 495 Japanese-Americans followed for an average of 5.3 years and of both appendicular and axial measurements among 70 clinical trial participants followed for 2 years. Tables were derived from these analyses to quantitate the precision of individual loss rates under varying measurement conditions that might be encountered in clinical practice. The results demonstrate that only unusually rapid loss rates could be identified with confidence within short intervals, such as 1 year or 2. Extending the length of follow-up, however, appreciably improved the measured loss rate precision. In comparisons between bone sites, appendicular sites were determined to achieve a specified precision within the shortest intervals, followed by spine dual photon absorptiometry measurements. Spine quantitative computerized tomography measurements and measurements of hip sites required considerably longer follow-up intervals to achieve comparable precision.     

Structural adaptations to bone loss in aging men and women

INTRODUCTION: Bone apposition on the subperiosteal surface and bone loss from the endocortical surface during aging establish the external diameter, total cross-sectional area (tCSA), cortical thickness (Ct.Th) and the distance the cortex is placed from the neutral axis of a long bone, all determinants of bone strength. We tested the hypothesis that sex-related differences in these processes produces a sexual dimorphism in tibial fragility. METHODS: The above traits were assessed in 688 women and 561 men (20-102 years old) using peripheral QCT. RESULTS: Total and medullary areas were greater in young adult men than young adult women. As age advanced, in men, tCSA area increased by 0.79 SD, and medullary area increased by 0.54 SD so that cortical area, cortical thickness and minimum and maximum moments of inertia (Imin and Imax) were similar at all ages. In women, tCSA increased by 0.2 SD, while medullary area increased by 2.6 SD so that cortical area and thickness and the moments of inertia diminished. Cortical apparent volumetric bone mineral density (vBMD) declined more in women (by 3.1 SD) than men (by 0.5 SD). In both sexes, the lower the cortical apparent vBMD, the higher the tCSA (women R2 = 0.13, men R2 = 0.16, both P < 0.0001), whereas the lower the Ct.Th, the lower the tCSA (women R2 = 0.30, men R2 = 0.32, both P < 0.0001). CONCLUSIONS: Bone loss reduces cortical thickness and increases intracortical porosity. These changes tend to be compensated for by periosteal apposition in both sexes but more greatly in men than in women, perhaps because this mechanism may be ineffective when cortical thinning is severe.     

Racial differences in bone mineral density in older men.

Studies have examined factors related to BMD in older white, but not black, men. We measured BMD in older white and black men and examined factors related to racial differences in BMD. Black men had significantly higher adjusted BMD at all sites. These results may explain, in part, the lower incidence of fractures in older black men. INTRODUCTION: Several studies have examined factors associated with bone mineral density (BMD)in older men. None, however, have had sufficient numbers of black men to allow for meaningful comparisons by race. MATERIALS AND METHODS: A total of 503 white and 191 black men aged 65 and older(75.1 +/- 5.8 and 72.2 +/- 5.7 years, respectively) were recruited from the Baltimore metropolitan area. All men completed a battery of self-administered questionnaires, underwent a standardized examination, and had BMD measured at the femoral neck, lumbar spine, and total body. Data were analyzed using multiple variable linear regression models, adjusted for potential confounding variables; two-way interactions with main effects were included in models where appropriate. RESULTS: Black men had significantly higher adjusted BMD at the femoral neck (difference 0.09 [95% CI: 0.07, 0.12] mg/cm2), lumbar spine (0.07 [0.04, 0.10] mg/cm2), and total body (0.06 [0.03, 0.08] mg/cm2) than white men. CONCLUSIONS: Older black men have significantly higher BMD than older white men, even after adjustment for factors associated with BMD. These differences, especially at the femoral neck, may explain the reduced incidence of hip fracture in black compared with white men.     

Racial differences in pre- and postmenopausal bone homeostasis: association with bone density.

The disparity in fracture incidence and bone mass in women of European (white) and African (black) ancestry is of unknown etiology. To determine if racial differences in bone mass reflected racial differences in the mechanisms of bone turnover underlying bone mineral loss, we measured serum osteocalcin, serum alkaline phosphatase, fasting urinary calcium and hydroxyproline excretion, 24 h urinary excretion of calcium and sodium, and dietary intakes of calcium and vitamin D in 263 healthy pre-, peri-, and postmenopausal white and black women. In addition, radial and spinal bone density were measured cross-sectionally for comparison with biochemical measures of bone turnover. The biochemical parameters thought to reflect bone resorption (fasting urinary calcium and hydroxyproline excretions) were lower in black than in white women throughout the age and menopausal stages studied. The parameters thought to reflect bone formation (alkaline phosphatase and osteocalcin), were similar in the two racial groups among the premenopausal women, but osteocalcin was significantly lower among the peri- and postmenopausal blacks. Cross sectionally measured radial bone density increased with age in premenopausal black women, but it did not change with age in the white premenopausal subjects, a statistically significant difference. In peri- and postmenopausal women radial density declined significantly with years after menopause in both racial groups, but the rate of decline was significantly slower in the black women. Lumbar bone density in premenopausal white and black women did not change with age. After menopause lumbar bone density declined significantly and similarly in both racial groups.(ABSTRACT TRUNCATED AT 250 WORDS)     

使用NORLAND骨密度仪比较不同人种峰值骨量值

目的了解不同人种的峰值骨量(PBM)差异。方法收集在西文SCI和中文NSTL核心期刊上发表的,使用NORLANDDXA骨密度仪测量的欧美白种人和亚洲黄种人的PBM值,按不同性别和测量部位进行分类比较。结果欧美白种人和亚洲黄种人在腰椎、股骨颈以及股骨粗隆的PBM值差异较大,其中女性白种人股骨颈、股骨粗隆和脊柱PBM要分别比女性黄种人高17.1%、17.8%和5.6%,男性白种人脊柱PBM要比男性黄种人高9.6%,而女性桡骨PBM值在不同人种中的差别不大。结论欧美白种人和亚洲黄种人不同部位PBM值存在一定差异。