Geographic differences in bone mineral density of Mexican women

Geographic variation in bone mineral density and prevalent fractures in the Canadian longitudinal study on aging

Awareness of the prevalence of osteoporosis and fractures across jurisdictions can guide the development of local preventive programs and healthcare policies. We observed geographical variations in total hip bone mineral density and in the prevalence of major osteoporotic fractures across Canadian provinces, which persisted after adjusting for important covariates.

PURPOSE

We aimed to describe sex-specific total hip bone mineral density (aBMD) and prevalent major osteoporotic fractures (MOF) variation between Canadian provinces.

METHODS

We used baseline data from 21,227 Canadians (10,716 women, 10,511 men) aged 50-85 years in the Canadian Longitudinal Study on Aging (CLSA; baseline: 2012-2015). Linear and logistic regression models were used to examine associations between province of residence and total hip aBMD and self-reported MOF, stratified by sex. CLSA sampling weights were used to generate the prevalence and regression estimates.

RESULTS

The mean (SD) age of participants was 63.9 (9.1) years. The mean body mass index (kg/m2) was lowest in British Columbia (27.4 [5.0]) and highest in Newfoundland and Labrador (28.8 [5.3]). Women and men from British Columbia had the lowest mean total hip aBMD and the lowest prevalence of MOF. Alberta had the highest proportion of participants reporting recent falls (12.0%), and Manitoba (8.4%) the fewest (p-value=0.002). Linear regression analyses demonstrated significant differences in total hip aBMD: women and men from British Columbia and Alberta, and women from Manitoba and Nova Scotia had lower adjusted total hip aBMD than Ontario (p-values<0.02). Adjusted odds ratios (95% confidence intervals, CI) for prevalent MOF were significantly lower in women from British Columbia (0.47 [95% CI: 0.32; 0.69]) and Quebec (0.68 [95% CI: 0.48; 0.97]) and in men from British Columbia (0.40 [95% CI:0.22; 0.71]) compared to Ontario (p-values<0.03). Results were similar when adjusting for physical performance measures and when restricting the analyses to participants who reported White race/ethnicity.

CONCLUSION

Geographical variations in total hip aBMD and in the prevalence of MOF between provinces persisted after adjusting for important covariates which suggests an association with unmeasured individual and environmental factors.

FNDC5/Irisin polymorphisms are associated with osteopenia in postmenopausal Mayan-Mestizo women

OBJECTIVE

This study aimed to analyze the association between rs3480 and rs16835198 of FNDC5/Irisin and their haplotypes with variations in bone mineral density (BMD) and osteopenia/osteoporosis in postmenopausal Mayan-Mestizo women.

METHODS

We studied 547 postmenopausal women of Maya-Mestizo origin. BMD was measured in the lumbar spine and total hip by dual-energy X-ray absorptiometry. DNA was obtained from blood leukocytes. rs3480 and rs16835198 of FNDC5/Irisin were studied using real-time PCR allelic discrimination. Differences between the means of BMD according to genotype were analyzed with covariance. Allele frequency differences were assessed by χ² and logistic regression was used to test for associations. Pairwise linkage disequilibrium between polymorphisms was calculated by direct correlation r², and haplotype analysis was conducted.

RESULTS

Under a recessive model, we observed a significant association of rs3480 with the presence of osteopenia at the total hip and femoral neck (p = 0.008 and p = 0.003, respectively). For rs16835198, we found an association with osteopenia at the total hip and femoral neck in a dominant model (p = 0.043 and p = 0.009, respectively).

CONCLUSIONS

We found an association of rs3480 with risk to present osteopenia at the total hip and femoral neck, while rs16835198 was associated as a protector for presence of osteopenia only at the femoral neck.

Bone Mineral Density and Fractures In Postmenopausal Women Of Mayan-Mestizo Ethnic Origin With Different Body Mass Indices

BACKGROUND

Obesity protects against bone loss, but it increases the risk of fragility fractures.

AIM

To determine if bone mineral density (BMD) and the prevalence of fractures are different in postmenopausal Mayan-mestizo women grouped according to their body mass index.

SUBJECTS AND METHODS

We studied 600 postmenopausal Maya-Mestizo women. A structured questionnaire for risk factors was applied. Body mass index (BMI) was determined. BMD was assessed at the lumbar spine and total hip by dual-energy X-ray absorptiometry. History of low trauma fracture was determined from medical records. ANOVA was used to compare mean BMD between women with different BMI. To compare the frequency of fractures according to BMI group, we used χ².

RESULTS

According to WHO classification of BMI, 16.3% of women had normal BMI, 35.3% were overweight, and 48.4% had obesity. We found that women with obesity had a higher BMD versus women with normal BMI or overweight in all the anatomical sites analysed. The prevalence of history of fractures was 18.2%. We did not find differences between the women of different BMI; the wrist was the most frequent skeletal site of the fracture.

CONCLUSIONS

Obesity in postmenopausal Maya-Mestizo women is not a risk factor for developing fragility fractures.

Genotypic Analyses of the Sclerostin rs851056 and Dickkopf rs1569198 Polymorphisms in Mexican-Mestizo Postmenopausal Osteoporosis: A Case-Control Study

Background: The Wnt/β catenin pathway promotes bone mineralization stimulating proliferation, differentiation, and survival of osteoblasts; it also inhibits osteoclast differentiation and osteocyte activity. Sclerostin (SOST) and Dickkopf 1 (DKK1) are Wnt/β catenin pathway inhibitors. Genetic variability in the expression of SOST and DKK1 might be involved in the development of postmenopausal osteoporosis (OP). Aim: To determine whether the SOST rs851056 and DKK1 rs1569198 polymorphisms are associated with OP in Mexican-Mestizo postmenopausal women. Materials and Methods: Two hundred and eighty Mexican-Mestizo postmenopausal women were assessed for their bone mineral density by dual-energy X-ray absorptiometry (DXA). Patients were classified as OP or non-OP. Genomic DNA was extracted from peripheral blood leukocytes. Genetic polymorphisms were analyzed by quantitative polymerase chain reaction using TaqMan probes. Results: The frequency of OP was 40% among the study population. Osteoporotic patients were older (p < 0.001), had a higher frequency of smoking (p = 0.01), and lower body mass index (p < 0.001) compared with the non-osteoporotic patients. The genotypic frequencies of the rs851056 locus of the SOST gene were GG 19%, GC 45%, and CC 35%, whereas the genotypic frequencies of the rs1569198 locus of the DKK1 gene were GG 15%, GA 40%, and AA 44%. In relation to rs851056 locus of the SOST gene, no differences were observed between the OP and non-OP cohorts in the frequencies of the GC polymorphism (48.7% vs. 43.1%). Similarly, analyses of the DKK1 rs1569198 does not demonstrate differences in the GA genotypic frequencies between the OP and non-OP cohorts (42.5% vs. 38.9%). Conclusion: Polymorphisms SOST rs851056 and DKK1 rs1569198 polymorphisms are not associated with OP in Mexican-Mestizo postmenopausal women.

Geographical differences in osteoporosis, obesity, and sarcopenia related traits in white American cohorts

It has been reported that geographical variation influences bone mineral density (BMD), obesity, and sarcopenia related traits in other countries. However, there is lack of similar studies in the US population. In this study, we compared data from three US study cohorts to evaluate geographical variations of BMD and body composition. BMD, fat mass and lean mass were collected from Dual-energy X-ray absorptiometry machine. ANCOVA and Chi-square tests were used to compare the differences between BMDs, obesity and sarcopenia related traits from different regional sites (Omaha, Kansas City and Baton Rouge/New Orleans). Eta-squared was used to measure the effect sizes of these differences. A total of 11,315 Caucasians from our previous three study cohorts were compared. There was no significant geographical difference in BMD for males or females under the criteria of p-values < 0.05 and effect size η² > 0.01. There were significant geographical differences with medium effect size (p-value < 0.001, 0.01 < η² < 0.14) for whole body fat mass percentage and index of low muscle mass. For Caucasians in the United States, there is no significant geographical effect found on BMD. The obesity and sarcopenia related traits are significantly different between the three study cohorts.

Association of RMND1/CCDC170-ESR1 single nucleotide polymorphisms with hip fracture and osteoporosis in postmenopausal women

OBJECTIVE

This study aimed to investigate the association of seven single nucleotide polymorphisms (SNPs) on the RMND1, CCDC170, and ESR1 genes with osteoporosis or hip fracture in a postmenopausal Mexican population.

METHODS

We included a group of 400 postmenopausal women from the Health Workers Cohort Study from the Mexican Institute of Social Security. As a replication sample, we recruited 423 postmenopausal women from the National Institute of Rehabilitation. Demographic data were collected through a structured questionnaire. Bone mineral density was assessed using dual X-ray absorptiometry. Individuals were classified as normal, osteopenia, osteoporosis, and fracture, according to World Health Organization criteria. Genotyping was performed using predesigned TaqMan Probes. Linear regression analysis was used to investigate association.

RESULTS

All of the analyzed SNPs showed association with at least one of the phenotypes of the study groups. In addition, we observed a region with linkage disequilibrium within the ESR1 gene in all groups.

CONCLUSION

This study shows that an association of the SNPs can exist with osteopenia, osteoporosis, or fragility fracture. Our results agree with data published elsewhere, supporting the potential of these loci for the identification of the population at risk. However, additional studies are required to determine the extent of this association for other geographic regions of Mexico.

JAG1, MEF2C and BDNF polymorphisms associated with bone mineral density in women from Northern México

Introduction: Osteoporosis is characterized by a low bone mineral density. Genetic composition is one of the most influential factors in determining bone mineral density (BMD). There are few studies on genes associated with BMD in the Mexican population. Objective: To investigate the association of eight single nucleotide polymorphisms (SNP) of JAG1, MEF2C and BDNF genes with BMD in women of Northern México. Materials and methods: This study involved 124 unrelated Mexican women between 40 and 80 years old. BMD was determined by dual X-ray absorptiometry. Genotyping was performed using allelic discrimination by real time PCR. We analyzed the SNP of JAG1 (rs6514116, rs2273061, rs2235811 and rs6040061), MEF2C (rs1366594, rs12521522 and rs11951031), and BDNF (rs6265) and the data using linear regression. Results: The JAG1 SNP rs2235811 was associated with the BMD of the total body under the dominant inheritance model (p=0,024). Although the other SNPs were not associated with BMD in any of the inheritance models studied, a trend was observed. Conclusion: Our results suggest that the SNP rs2235811 in the JAG1 gene might contribute to the variation in BMD in women from northern México.

Bone mineral density in healthy Syrian women measured by dual energyX-ray absorptiometry

Assessment of bone mineral density (BMD) using dual energy X-ray absorptiometry (DXA) technique is considered as a standard technique for diagnosing osteopenia and osteoporosis and evaluating the severity of such diseases. Numerous studies have demonstrated the necessity to establish an ethnicspecific reference data for Bone mineral density measurements. Such data are lacking for the Syrian population. The objectives of this study are (1) to establish BMD reference values in a group of healthy Syrian women using DXA technique, (2) to compare with values from other populations, (3) to study the prevalence of osteopenia and osteoporosis in Syrian women using the manufacturer reference values. A total of 951 healthy Syrian women aged 20-79 years participated in this study. Weight, height, and BMI have been determined. BMD measurements were performed using Lunar Prodigy Advance System (GE). The data were compared with those from other populations. The results have demonstrated the expected decline in BMD with age after peaking at 30-39 years old group. The peak values of the lumbar spine and femur neck were 1.16 (0.12), and 0.95 (0.13) g/cm2, respectively. The results of the Syrian women were compared with those from other populations and the differences were presented. Osteopenia was diagnosed in 35.80% and 60.31% and osteoporosis in 6.23% and 2.72% in lumbar spine and femur neck, respectively, of women 50-59 years of age. These ratios increased to 36.84%, 68.42% and 23.68%, 13.10%, respectively, in the age group more than 59 years. BMD values of the Syrian women were determined for the first time. The results demonstrate the importance of establishing population-specific reference range for BMD values for an accurate assessment of Osteoporosis. High prevalence of osteopenia and osteoporosis was demonstrated in Syrian using the manufacturer reference values.

A Pilot Genome-Wide Association Study in Postmenopausal Mexican-Mestizo Women Implicates the RMND1/CCDC170 Locus Is Associated with Bone Mineral Density

To identify genetic variants influencing bone mineral density (BMD) in the Mexican-Mestizo population, we performed a GWAS for femoral neck (FN) and lumbar spine (LS) in Mexican-Mestizo postmenopausal women. In the discovery sample, 300,000 SNPs were genotyped in a cohort of 411 postmenopausal women and seven SNPs were analyzed in the replication cohort (n = 420). The combined results of a meta-analysis from the discovery and replication samples identified two loci, RMND1 (rs6904364, P = 2.77 × 10^-4) and CCDC170 (rs17081341, P = 1.62 × 10^-5), associated with FN BMD. We also compared our results with those of the Genetic Factors for Osteoporosis (GEFOS) Consortium meta-analysis. The comparison revealed two loci previously reported in the GEFOS meta-analysis: SOX6 (rs7128738) and PKDCC (rs11887431) associated with FN and LS BMD, respectively, in our study population. Interestingly, rs17081341 rare in Caucasians (minor allele frequency < 0.03) was found in high frequency in our population, which suggests that this association could be specific to non-Caucasian populations. In conclusion, the first pilot Mexican GWA study of BMD confirmed previously identified loci and also demonstrated the importance of studying variability in diverse populations and/or specific populations.

Prevalence of Osteoporosis and Low Bone Mass in Older Chinese Population Based on Bone Mineral Density at Multiple Skeletal Sites

Diagnosis of osteoporosis is based on bone mineral density (BMD) measurement, which is site dependent and commonly discordant between measurement sites. We aimed to determine the prevalence of osteoporosis diagnosed based on BMD T-scores measured by dual-energy x-ray absorptiometry (DXA) at different sites: the lumbar spine (LS) alone, femoral neck (FN) alone, or both. A total of 1712 women and 2028 men with LS and FN BMD measurements were enrolled. Over 50% discordance was found between osteoporosis classifications based on T-scores measured at the LS and FN. Use of the lowest T-scores measured at both the LS and right and left FN (rather than one site) significantly increased the prevalence of osteoporosis from 4.03 to 10.75% in postmenopausal women and 1.82 to 4.29% in men aged ≧50 years (p < 0.001). The trends of overall and age-adjusted prevalence of osteoporosis were similar in women and men. Osteoporosis was diagnosed at a higher rate if the USA reference rather than the Asia reference was used to calculate the T-score (26.64% vs. 10.75%). In conclusion, diagnosis based on the lowest T-score from multiple site BMD measurement can increase the prevalence of osteoporosis, demonstrating the higher sensitivity of the multiple site measurement strategy.

New reference data on bone mineral density and the prevalence of osteoporosis in Korean adults aged 50 years or older: the Korea National Health and Nutrition Examination Survey 2008-2010

This cross-sectional study was performed to investigate the reference values for bone mineral density (BMD) measured by dual-energy X-ray absorptiometry (DXA) and the prevalence of osteoporosis in the Korean population by applying domestic reference data. In total, 25,043 Korean adults ≥20 yr of age (11,792 men and 13,251 women) participated in the study. The BMDs of the total hip, femoral neck, and lumbar spine were measured by DXA (Discovery-W, Hologic Inc.), and subjects with a BMD - 2.5 standard deviations or lower than the mean BMD for young adults (20-29 yr old) were considered to have osteoporosis. When applying the new reference values determined in this study from Korean subjects, the overall prevalence of osteoporosis increased in men aged ≥50 yr compared with that provided by the DXA manufacturer from Japanese subjects (12.2% vs. 7.8%, P<0.001) and decreased in postmenopausal women aged ≥50 yr (32.9% vs. 38.7%, P<0.001). According to the findings of this study, use of the reference values provided by the DXA manufacturer has resulted in the underdiagnosis of osteoporosis in Korean men and the overdiagnosis of osteoporosis in Korean women. Our data will serve as valuable reference standards for the diagnosis and management for osteoporosis in the Korean population.

WNT3A gene polymorphisms are associated with bone mineral density variation in postmenopausal mestizo women of an urban Mexican population: findings of a pathway-based high-density single nucleotide screening

Osteoporosis (OP) is a common skeletal disorder characterized by low bone mineral density (BMD) and is a common health problem in Mexico. To date, few genes affecting BMD variation in the Mexican population have been identified. The aim of this study was to investigate the association of single nucleotide polymorphisms (SNPs) located in genes of the Wnt pathway with BMD variation at various skeletal sites in a cohort of postmenopausal Mexican women. A total of 121 SNPs in or near 15 Wnt signaling pathway genes and 96 ancestry informative markers were genotyped in 425 postmenopausal women using the Illumina GoldenGate microarray SNP genotyping method. BMD was measured by dual-energy X-ray absorptiometry in total hip, femoral neck, Ward's triangle, and lumbar spine. Associations were tested by linear regression for quantitative traits adjusting for possible confounding factors. SNP rs752107 in WNT3A was strongly associated with decreased total hip BMD showing the highest significance under the recessive model (P = 0.00012). This SNP is predicted to disrupt a binding site for microRNA-149. In addition, a polymorphism of the Wnt antagonist DKK2 was associated with BMD in femoral neck under a recessive model (P = 0.009). Several LRP4, LRP5, and LRP6 gene variants showed site-specific associations with BMD. In conclusion, this is the first report associating Wnt pathway gene variants with BMD in the Mexican population.

Prevalence of low bone mass in postmenopausal Kuwaiti women residents in the largest province of Kuwait

We measured bone mineral density (BMD) in Kuwaiti women residents in the largest province of Kuwait state to highlight the BMD changes with each age, in particular when they reach the postmenopausal stage. Healthy Kuwaiti females between the ages of 10 and 89 years, who were residents in the largest province of Kuwait, were included in the study. After measurements of their height and weight, their bone mineral density of L2-L4 lumbar spine and femur (neck and total) was measured using dual-energy X-ray absorptiometry. Out of the studied 903 female subjects, 811 fulfilled the inclusion criteria. Their mean ± SEM age and body mass index (BMI) were respectively 47 ± 1 years and 30.8 ± 0.2 kg/m(2). Out of these 811 subjects, 454 were postmenopausal, and their age and BMI were 55.0 ± 0.3 years and 32.0 ± 0.3 kg/m(2), respectively. We have demonstrated that osteoporotic BMD of the spine and femur neck occurred in 20.2 and 12.5 % of postmenopausal Kuwaiti females, whereas osteopenic BMD of the spine and femur neck was observed at a frequency of 35.4 and 42.8 % of women, respectively. When the subjects were subdivided as per BMI, it was notable that overweight and obese had significantly higher BMD than normal weight postmenopausal women. BMD of the spine, femur neck, and femur total demonstrated significant positive correlations with body weight and BMI, whereas they demonstrated significant negative correlations with age. Low BMD of the femur neck and spine, reflected by the combination of osteopenia and osteoporosis, seemed to occur in more than half (55.3-55.6 %) of postmenopausal Kuwaiti women.

OBJECTIVES

Most of the studies on assessment of prevalence of low bone mass were focused in Caucasian population. Data on subjects of the Mediterranean area are limited. We measured bone mineral density (BMD) in Kuwaiti women residents in the largest province of Kuwait state to highlight the BMD changes with each age, in particular when they reach the postmenopausal stage.

SUBJECTS AND METHODS

Kuwaiti female subjects of different age groups between 10 and 89 years, who were residents in the largest province of Kuwait (Hawalli), were included in the study. They were included if they had been healthy over the last 12 months, had no past history of bone disease, and are not taking any prescription medication that may affect bone density. Their bone mineral density of L2-L4 lumbar spine and femur (neck and total) was measured using dual-energy X-ray absorptiometry.

RESULTS

Out of the studied 903 female subjects, 811 fulfilled the inclusion criteria and were included in the study. Their mean ± SEM age and body mass index (BMI) were respectively 47 ± 1 years and 30.8 ± 0.2 kg/m(2). Out of these 811 subjects, 454 were postmenopausal, and their age and BMI were 55.0 ± 0.3 years and 32.0 ± 0.3 kg/m(2), respectively. We have demonstrated that osteoporotic BMD of the spine and femur neck occurred in 20.2 and 12.5 % of postmenopausal Kuwaiti females, respectively, whereas osteopenic BMD of the spine and femur neck was observed at a frequency of 35.4 and 42.8 % of women. When subjects were subdivided as per BMI, it was notable that overweight and obese postmenopausal women had significantly higher BMD of lumbar spine, femur neck, and femur total than normal weight postmenopausal women. Bone mineral densities of the spine, femur neck, and femur total demonstrated significant positive correlations with body weight and BMI, whereas they demonstrated significant negative correlations with age.

CONCLUSION

Low BMD of the femur neck and spine, reflected by the combination of osteopenia and osteoporosis, seemed to occur in more than half (55.3-55.6 %) of postmenopausal Kuwaiti women residents at the largest province of Kuwait.

Osteoporosis and fragility fractures

The prevalence of osteoporosis is expected to increase with the ageing of the world's population. This article reviews the epidemiology, risk factors and health burden of osteoporosis. In the Global Burden of Disease (GBD) Study 2005, osteoporosis is studied as a risk factor for fracture by considering the bone-mineral-density (BMD) measurement as the continuous exposure variable. We have performed a systematic review seeking population-based studies with BMD data measured by dual-X-ray absorptiometry (DXA). The femoral neck was selected as the unique location and all values were converted into Hologic(®) to enable inclusion of worldwide data for analysis. Provisional results on mean BMD values for different world regions are shown in age breakdowns for males and females 50 years or over, as well as mean T-scores using the young, white, female reference of National Health and Nutrition Examination Survey (NHANES) III. Results show remarkable geographical differences and a time trend towards improvement of the BMD values in Asian and European populations.

Bone mass in schoolchildren in Brazil: the effect of racial miscegenation, pubertal stage, and socioeconomic differences

The purpose of this study was to evaluate bone mass by phalanges ultrasound in healthy white and black schoolchildren in relationship to socioeconomic level, pubertal stage, and body composition. Included were 1,356 healthy schoolchildren aged from 6 to 11 years from different socioeconomic levels and both genders; all were placed into white and black groups. Weight, height, body mass index, fat percentage, fat mass, and lean mass were evaluated by anthropometric methods, and AD-SoS bone quantity and UBPI bone quality were evaluated using a third-generation IGEA phalanges DBM Sonic BP ultrasound. Data were compared using the Mann-Whitney, chi-squared, correlation coefficient, and analyses of multiple linear regression statistical tests with 5% significance. Black schoolchildren predominated in the low socioeconomic levels. Higher values of weight and height for black boys and girls were observed in the lean mass in relation to white children of the same gender and age. An increasing variation in the bone quantity mean was observed from 6 to 11 years of age and with pubertal stage for both genders and skin color. The white schoolchildren presented higher values of bone quantity and quality in relation to the black children. The anthropometric, gender, and socioeconomic level variables explained only 16 and 11% of the variability of bone quantity and quality, respectively. As such, the present study, carried out with healthy black and white Brazilian schoolchildren, demonstrated higher bone mass, as evaluated by ultrasound, in white than in black schoolchildren.

Active comparator trial of teriparatide vs alendronate for treating glucocorticoid-induced osteoporosis: results from the Hispanic and non-Hispanic cohorts

Glucocorticoid use is a leading cause of secondary osteoporosis. This post hoc analysis compared teriparatide vs alendronate on bone mineral density (BMD) in Hispanic and non-Hispanic patients with glucocorticoid-induced osteoporosis. The 18-mo results from all patients (N=428) in a double-blind trial of teriparatide (20 microg/d) and alendronate (10 mg/d) who had taken glucocorticoids for >or=3 mo were reported (Saag et al. N Engl J Med 2007). The present study analyzed results from the Hispanic (n=61) and non-Hispanic (n=367) cohorts. The BMD was measured by dual-energy X-ray absorptiometry (DXA). In the Hispanic cohort at 18 mo, there were significantly greater increases from baseline in the teriparatide vs alendronate group in lumbar spine BMD (9.8%+/-1.7% vs 4.2%+/-1.4%; p<0.001; mean+/-SE) and total hip BMD (5.9%+/-1.6% vs 1.3%+/-1.3%, p<0.001), with no significant difference between groups at the femoral neck (4.3%+/-2.2% vs 2.0%+/-1.8%, p=0.228). Within each treatment group, the BMD responses were not significantly different in the Hispanic vs non-Hispanic cohort. The number of patients reporting >or=1 adverse event was not significantly different between treatments in either cohort, with more patients reporting nausea in the teriparatide group. In summary, teriparatide was more efficacious than alendronate in increasing BMD in Hispanic and non-Hispanic patients with glucocorticoid-induced osteoporosis. Both treatments were generally well tolerated.

Geographic variation of bone mineral density and selected risk factors for prediction of incident fracture among Canadians 50 and older

BACKGROUND

Striking geographic variation in the incidence of osteoporotic fracture has been shown in national and international studies. The contributing risk factors for this variation are not fully understood.

OBJECTIVE

To determine the geographic variation of bone mineral density (BMD) values, prevalent low-trauma fracture, prior falls, and vertebral deformity and to determine how this variation is related to the geographic variation of incident low-trauma fracture.

METHODS

We studied incident fracture among 2484 men and 6093 women ages 50 and older from CaMos, a randomly-selected population-based longitudinal cohort recruited from within 50 kilometers of nine cities across Canada. Analyses included up to an eight-year follow-up.

RESULTS

Estimates of fracture incidence are all age-standardized and given per 1000 person-years and CI denotes confidence interval. Among men, the lowest incidence of low-trauma fracture was 3.2 (95% CI: 1.1-7.5) in Quebec and the highest was 11.9 (95% CI: 7.1-18.6) in Calgary, compared with an overall incidence of 7.2 (95% CI: 5.8-8.7). Among women, the lowest incidence of low-trauma fracture was 11.5 (95% CI: 8.5-15.1) in Halifax and the highest was 18.5 (95% CI: 14.6-23.3) in Calgary, compared with an overall incidence of 15.3 (95% CI: 14.1-16.7). The regional variation in low-trauma fractures was similar to variation in hip fracture incidence among women (Pearson correlation, r=0.46 to 0.76) but not men (r=-0.06 to 0.05). We noted significant geographic variation in the prevalence of low BMD, as defined by BMD T-score< or =-2.5, however this variation was not directly related to low-trauma fractures or other risk factors. Furthermore, a model including age, BMD, falls, vertebral deformity, and prior clinical fracture was a good predictor of geographic variation of low-trauma fracture incidence in both men (r=0.66) and women (r=0.84).

CONCLUSIONS

For both men and women, the burden of low-trauma fracture is not related to the prevalence of osteoporosis as defined by BMD, but is related to a more comprehensive assessment of fracture risk including the following: age, BMD, falls, prior fracture, and vertebral deformity.

Hip axis length variation: its correlation with anthropometric measurements in women from three ethnic groups

We compared hip axis length (HAL) in 157 non-Hispanic white women, 292 African-American women, and 210 Mexican-American women. After adjusting for maximal hip girth, there were no residual differences in HAL by ethnicity. Differences in hip fracture risk seen between these groups cannot be explained by ethnic differences in HAL.

INTRODUCTION

Hip axis length (HAL) has been reported to be an independent predictor of hip fracture. Significant ethnic differences in HAL have been noted, but no direct comparison has been made between African-American, Mexican-American, and non-Hispanic white women using the same protocol.

METHODS

We compared 157 non-Hispanic white women from the Rancho Bernardo Study, 292 women from the Health Assessment Study of African-American Women, and 210 women from the Skeletal Health of Mexican-American Women Project. A standardized questionnaire was used to obtain medical history; height, weight, waist girth, and hip girth were measured; and percentage body fat and HAL were obtained using dual energy X-ray absorptiometry. All HAL comparisons were adjusted for maximum hip girth to control for differences in size magnification by fan-beam absorptiometry.

RESULTS

Though there were ethnic differences in the unadjusted HAL measurement, after adjusting for hip circumference, there were no residual differences in HAL with regard to ethnicity: 10.7 cm in Mexican-American women vs. 10.8 in non-Hispanic white women and African-American women (p = 0.61).

CONCLUSIONS

There were no ethnic differences in HAL in women from the three ethnic groups. Differences in fracture risk among these groups cannot be explained by ethnic differences in HAL.

Body composition and bone density in Canadian White and Aboriginal women: the First Nations Bone Health Study

Ethnic variation in soft tissue composition may contribute to observed ethnic differences in bone mineral density (BMD). This analysis was performed to determine whether ethnic differences in body composition affect differences in BMD between Canadian White and Aboriginal women. An age-stratified population-based sample of 206 Aboriginal women and 177 White women underwent multisite bone density measurements and total body soft tissue composition analysis. In univariate analyses, each kg of additional lean mass was associated with a greater increase in BMD than an equal amount of fat mass (p<.01). When models simultaneously evaluated both soft tissue measurements, lean mass (but not fat mass) was positively correlated with BMD at all measurement sites (p<.001). Aboriginal women had significantly lower weight-adjusted BMD than White women for two sites (calcaneus, p = .019; total body, p = .026) and lower BMI-adjusted for BMD three sites (calcaneus, p = .0076; distal forearm, p = .047; total body, p = .022). The ratio of lean mass to fat mass was lower in Aboriginal than White women (p<.001). When BMD was adjusted for body composition variables no significant difference was seen between Aboriginal and White women. Apparent ethnic differences in weight- and BMI-adjusted BMD between Canadian White and Aboriginal women were explained by a lower ratio of lean mass to fat mass in Aboriginal women, combined with a smaller increment in BMD from fat mass versus lean mass in both populations.

Establishment of BMD reference databases for the diagnosis and evaluation of osteoporosis in central southern Chinese men

Osteoporosis in men is an increasingly important public health problem. This study was designed to establish bone mineral density (BMD) reference databases for central southern Chinese men at multiple skeletal sites. We recruited 2433 native Chinese males for BMD assessment. Of these, 1537 were healthy volunteers (age range, 15-85 years), and 896 were suspected to have osteoporosis. BMD values were measured at the posteroanterior (PA) and lateral spine, hip, and distal forearm using a Delphi A absorptiometer. The quadratic regression model provided the best fit for age-related changes in BMD in the spine and hip. The cubic regression model was the best for describing age-related BMD changes in the distal forearm. Peak BMD in the lumbar spine, femoral neck, and total hip occurred at 15-19 years. Peak BMD at the distal forearm occurred at 40-44 years. The prevalence of primary osteoporosis in subjects ranging from 50-85 years was 4.3%-27.7% at various skeletal sites. Compared to the databases established here, the Hologic databases led to significantly higher osteoporosis detection rates. The BMD reference databases established for central southern Chinese men provide the most reliable diagnostic standards for osteoporosis detection in men of central south China.

Effects of the sample size of reference population on determining BMD reference curve and peak BMD and diagnosing osteoporosis

Establishing reference databases generally requires a large sample size to achieve reliable results. Our study revealed that the varying sample size from hundreds to thousands of individuals has no decisive effect on the bone mineral density (BMD) reference curve, peak BMD, and diagnosing osteoporosis. It provides a reference point for determining the sample size while establishing local BMD reference databases.

INTRODUCTION

This study attempts to determine a suitable sample size for establishing bone mineral density (BMD) reference databases in a local laboratory.

METHODS

The total reference population consisted of 3,662 Chinese females aged 6-85 years. BMDs were measured with a dual-energy X-ray absorptiometry densitometer. The subjects were randomly divided into four different sample groups, that is, total number (Tn) = 3,662, 1/2n = 1,831, 1/4n = 916, and 1/8n = 458. We used the best regression model to determine BMD reference curve and peak BMD.

RESULTS

There was no significant difference in the full curves between the four sample groups at each skeletal site, although some discrepancy at the end of the curves was observed at the spine. Peak BMDs were very similar in the four sample groups. According to the Chinese diagnostic criteria (BMD >25% below the peak BMD as osteoporosis), no difference was observed in the osteoporosis detection rate using the reference values determined by the four different sample groups.

CONCLUSIONS

Varying the sample size from hundreds to thousands has no decisive effect on establishing BMD reference curve and determining peak BMD. It should be practical for determining the reference population while establishing local BMD databases.

Differences in age-related bone mass of proximal femur between Chinese women and different ethnic women in the United States

Substantial racial differences in bone mass and bone loss rate have been reported, but the extent of the difference between native Chinese women and women of different races in the United States is not clear. We used a DXA bone densitometer to measure bone mineral density (BMD), bone mineral content (BMC), bone area (BA), and volumetric BMD (vBMD) in different regions of the proximal femur in 3614 Chinese women aged 20 years and older. Regression models were chosen to best fit the changes of these parameters with increasing age. The values in their fitted curves were determined by the Cartesian coordinate numeration system. Subsequently, we compared these fitted curves to full-matched data of non-Hispanic black, non-Hispanic white, and Mexican American women reported by the third National Health and Nutrition Examination Survey (NHANES III). We found that all fitted curves of bone mass of non-Hispanic black women were significantly higher than those of Chinese, non-Hispanic white, and Mexican American women (P = 0.000). The BMD and BMC fitted curves in various regions of the hip for non-Hispanic blacks were 22%-28% and 26%-43% higher than those for Chinese women, 8.3%-13% and 7.9%-9.5% higher than those for non-Hispanic whites, and 8.8%-10% and 13%-19% higher than those for Mexican Americans, respectively. However, when the expression of difference was transformed from BMD to vBMD at the femoral neck, the difference between Chinese and non-Hispanic black women was reduced from 22% to 18% and that between Chinese and non-Hispanic white women from 7.4% to 0.8%, but the difference increased from 3.2% to 9.6% between non-Hispanic white and Mexican American women and from 13% to 17% between non-Hispanic white and non-Hispanic black women. By the age of 80 years, the accumulated bone loss rate in various regions of the proximal femur for Chinese, Mexican Americans, non-Hispanic whites, and non-Hispanic blacks were -38.9% +/- 1.8%, -34.4% +/- 3.1%, -27.8% +/- 5.9%, and -28.4% +/- 4.8%, respectively. In conclusion, bone mass in the proximal femur of native Chinese women is significantly lower, and the bone loss rate greater, than those of non-Asian women in the United States. At the femoral neck, the vBMD of Chinese women is similar to that of non-Hispanic white women.

Bone density and bone area in Canadian Aboriginal women: the First Nations Bone Health Study

INTRODUCTION

Canadian Aboriginal women are at increased risk of fracture compared with the general population.

HYPOTHESIS

There is disproportionately reduced bone density in Aboriginal women as compared to white females of similar age.

METHODS

A random age-stratified (25-39, 40-59 and 60-75) sample of Aboriginal women (n=258) and white women (n=181) was recruited. All subjects had calcaneus and distal forearm bone density measurements, and urban participants (n=397 [90.4%]) also had measurements of the lumbar spine, hip and total body.

RESULTS

Unadjusted measurements were similar in the two groups apart from the distal forearm which showed a significantly lower mean Z-score in the Aboriginal women (p=0.03). Aboriginal women were heavier than white women (81.0+/-18.0 kg vs. 76.0+/-18.0 kg, p=0.02). Weight was directly associated with BMD at all measurement sites (p<0.00001) and potentially confounded the assessment of ethnicity on bone mass measurements. Weight-adjusted ANCOVA models demonstrated significantly lower bone density in Aboriginal than white women for the calcaneus, distal forearm, and total body (all p<0.05), but not at the other sites. ANCOVA models (adjusted for age, height and weight) were used to explore differences in bone area and bone mineral content (BMC). There was a significant effect of ethnicity on bone area with Aboriginal women having larger adjusted mean values than white women (lumbar spine p=0.038, total hip p=0.0004, total body p=0.020). In contrast, there was no detectable effect of ethnicity on BMC (all p>0.2).

CONCLUSIONS

We identified significant site-specific differences in age-and weight-adjusted bone density for Aboriginal and white women. Larger bone area, rather than a reduction in BMC, appeared to be primarily responsible. Further work is needed to define how these differences in bone density and geometry affect indices of bone strength.

Race/ethnicity and fracture risk assessment: an issue that is more than skin deep

The study of race/ethnicity in relation to health outcomes and health disparities is of great importance in medicine. This is as true in the field of osteoporosis as it is in others, and it comes into sharp focus when the question of population-specific reference data for bone densitometry arises. Race/ethnicity can be viewed as both an ecosocial construct and as a biomedical concept. Whether or not, and how, to use race/ethnicity in fracture assessment potentially places these two paradigms in opposition. In this article, some of the issues that need to be considered to develop a rational approach to reference data selection and a globally acceptable measure of fracture risk are reviewed. Race/ethnicity is often a proxy for other disease-related risk factors. Understanding fundamental risk factors goes beyond the language of race/ethnicity.

Ethnic Variation in Risk for Osteoporosis among Women: A Review of Biological and Behavioral Factors

Most studies of risk factors for osteoporosis and nontraumatic fracture involve white women, although more research is being geared toward bone health among various ethnic groups. The purpose of this review is to provide an overview of health disparity in osteoporosis, including assessment of bone mineral density (BMD), bone health screening, lifestyle risk factors, and treatment involving white, black, Hispanic, Asian, and Native American women. This review summarizes evidence that white, Asian, Hispanic, and Native American women are more at risk for osteoporosis than black women. These conclusions are supported by the disparity in BMD between white and black women, although the reason for this biological difference is not well characterized. Additional research is needed to determine if there is a significant difference in BMD among Hispanic, Asian, and Native American women independent of body weight and size. Similarly, there is also disparity in fracture rates, with the causes presumed to be multifactorial. Calcium intake is lower than recommended in all females at all ages; however, it is much lower in black and Native American women and highest in white and Hispanic women. Black women also have a lower vitamin D status than white women, with mean vitamin D status of Hispanic American women lying between that of black and white women. Similarly, although white women are more active than black and Hispanic women at all ages, data are lacking about physical activity habits of women of other ethnic backgrounds and how this impacts bone health. Finally, screening protocols for women of various ethnicities and effectiveness of treatments are not well established and remain a priority in women's health.

Comparison of spine and femur reference data in native Chinese women from different regions of China

The aim of this study is to explore the differences of BMD reference curves at various skeletal sites among Chinese women from different regions of China and to investigate the feasibility of establishing a unified national BMD reference database for Chinese women. We measured BMD at the posteroanterior (PA) lumbar spine, femoral neck, trochanter and Ward's triangle by dual-energy X-ray absorptiometry bone densitometer in 3,422 Changsha women of South Central China, aged 20-84 years. The documented BMDs of reference populations of women in all other areas included Shanghai ( n =2,111) and Nanjing ( n =3,174) in the East, Shenyang ( n =1,213) in the Northeast, Kunming ( n =523) in the Southwest, Chongqing ( n =811) in the Midwest and Xian ( n =1,320) in the Northwest. We adopted the cubic regression as the fitting model for reference curves of BMD that varied with age, conducted conversions of BMD measured by various bone densitometers from different manufacturers and compared the differences between standardized BMD (sBMD) reference curves and combined ones for women from different areas. Our results revealed that by comparing variances in women from different areas, the average variances of non-standard BMD were 0.8-30.8% at the PA spine, 0.7-24.5% at the femoral neck, 0.6-29.9% at the trochanter and 1.1-54.7% at Ward's triangle, while average variances of sBMD either significantly decreased or disappeared (0.8-3.9% at the PA spine, 0.7-8.6% at the femoral neck, 0.6-8.3% at the trochanter and 1.1-29.9% at Ward's triangle). The sBMD reference curves were highly positive-dependent with combined ones ( r =0.913-0.999, P =0.000). At the PA spine and trochanter, the effect of combined sBMD curves presented well in women from different areas, except for those from Shanghai at the PA spine and Shenyang at the trochanter, indicating that sBMD curves were significantly different from pooled ones; at the femoral neck and Ward's triangle, the effect of combined sBMD reference curves was poor, indicating that sBMD curves demonstrated significant differences from pooled ones in women from a majority of these areas. We conclude that, in high density population areas, sBMD reference curves showed no significant geographic differences in women from various regions. In women from different areas, sBMD reference curves present good pooled results at the PA spine and trochanter. The less ideal combining effect of the sBMD curves at both femoral neck and Ward's triangle might be caused by the intrinsic differences from the different measuring instruments.

The burden of osteoporosis in Latin America

Osteoporosis causes considerable morbidity, mortality and resource utilization in industrialized nations. Its burden is relatively well known in United States and Canada, but poorly studied in the rest of America. This study aimed to discover the burden of osteoporosis in Latin America through a review of literature and publicly available information. In this transversal and descriptive study, information from 20 countries in Latin American region was collected from diverse published and electronic sources. Rheumatologists and bone specialists were asked for additional information through a questionnaire created by consensus. In the year 2000, the population of the Latin America and Caribbean region was 524 million from diverse ethnic origins. On average, 5.5% of the population is 65 years and older. However, with life expectancy higher than 70 years in most countries, a significant growth in the elderly population is anticipated. Studies using World Health Organization's criteria for osteoporosis report 12-18% of women 50 years and older with vertebral osteoporosis and 8-22% with proximal femur osteoporosis. Community based studies in Argentina reported between 263 and 331 hip fractures per 100,000 people 50 years and older. Hospital based studies in Colombia, Chile, Brazil, Mexico, Panama, Peru and Venezuela reported between 40 and 362 hip fractures per 100,000 persons aged 50 and more. Between 17 and 37% of hip fracture sufferers die in the year following fracture. Prevalence of vertebral fractures in community-dwelling women aged 50 and more in Mexico is 19.35%. Data on other fractures are rare. Direct costs of a hip fracture ranged from $4500 to $6000. National gross income per capita in the region ranges from $410 to $7550. The burden of osteoporosis varies across countries with differences in populations and health resources. Considerable support for research is required, since numerous gaps in knowledge need to be filled to face the anticipated explosive growth in osteoporotic fractures.

Increasing hip fracture incidence in California Hispanics, 1983 to 2000

BACKGROUND

Hip fracture incidence in non-Hispanic whites (NHW) has decreased nationwide for the past 20 years. Little is known regarding hip fracture incidence among Hispanics, the largest, fastest growing minority in the United States.

OBJECTIVE

To assess the change in standardized hip fracture incidence from 1983 through 2000 in California Hispanics relative to other racial groups.

DESIGN

Hospitalizations for individuals older than 55 years with hip fracture requiring repair in acute care hospitals. Annual population estimates based on US Census Bureau estimates. Incidence standardized to national gender-age strata. Change in annual incidence calculated by weighted linear regression with robust variance estimates.

RESULTS

372,078 hip fractures were identified. Age-adjusted annual incidence of hip fractures declined by 0.74% per year among women (655 to 568 per 100,000), but was unchanged among men (247 to 238 per 100,000). Among NHW women, the standardized annual incidence fell by 0.6% (4.0 fractures per 100,000) per year. Annual incidence among Hispanic women increased 4.9% (11.1 fractures per 100,000) per year. Annual incidence among Hispanic men increased by 4.2% (4.5 fractures per 100,000) per year and among NHW men by 0.5% (1.2 fractures per 100,000) per year. No significant change occurred among black or Asian women or men.

CONCLUSIONS

Among California women, hip fracture incidence has doubled among Hispanics since 1983, while remaining unchanged or declining in other groups. Greater attention should be given to identification of individuals at risk for hip fracture and initiation of preventive measures in Hispanic populations.

Predictors of bone mineral density in female workers in Morelos State, Mexico

BACKGROUND

Although several studies have identified factors associated with bone mineral density (BMD), little research is available on Mexican women.

METHODS

A cross-sectional study was conducted in 1,622 female workers between 20 and 80 years of age at the Mexican Social Security Institute (IMSS), an integral part of the Mexican health system. It was carried out in Morelos, a Mexican state that borders Mexico City. Women were recruited to participate in this study from their workplaces. Body mass index (BMI) was measured and BMD was assessed using dual-energy x-ray absorptiometry of dominant forearm. Predictors of BMD (age, reproductive factors, BMI, diet, and physical activity) in pre- and postmenopausal women were assessed by questionnaire and analyzed using generalized additive models.

RESULTS

In premenopausal women, older age, higher BMI, younger age at menarche, and greater vitamin D intake were associated with higher BMD (R(2)=0.06, null deviance reduction=6.9%). In postmenopausal women, determinants of BMD were older age, higher BMI, greater height, later initiation of menopause, longer time of use of hormonal replacement therapy (HRT), and greater calcium intake from dairy products (R(2)=0.39, null deviance reduction=40.7%).

CONCLUSIONS

As observed in other populations, age, BMI, height, age at menopause, time of use of HRT, and calcium intake derived from dairy products in these Mexican women are factors associated with higher forearm BMD during postmenopausal period. Age, BMI, age at menarche, and vitamin D are associated with higher forearm BMD in premenopausal women. Some of these factors are not linearly associated with BMD. This was a limited population study carried out in a large group of female healthcare workers whose reproductive and lifestyle factors potentially agreed with those of female workers from urban areas of Mexico.

Effects of projective bone area size of the spine on bone density and the diagnosis of osteoporosis in healthy pre-menopausal women in China

The aim of this study was to understand the effects of projective bone area (BA) size of the spine on bone density and the diagnosis of osteoporosis. Measurements of BA, bone mineral content (BMC), areal bone density (aBMD) and volumetric bone density (vBMD) at the posteroanterior (PA) lumbar spine (vertebrae L2-L4) followed by a paired PA/lateral spine (L2-L4) were made using a dual-energy X-ray absorptiometry (DXA) fan-beam bone densitometer (Hologic QDR 4500A) in 1436 healthy pre-menopausal women aged from 20 to 56-years-old. At the PA and lateral lumbar spine, there was a significant positive correlation between BA and BMC (r=0.762 and 0.762, p=0.000) and aBMD (r=0.370 and 0.352, p=0.000), but not vBMD (r=0.000 and 0.102, p=0.813 and 0.063). When BA at the PA spine changed by one standard deviation (SD), BMC and aBMD correspondingly changed by 12.6% and 4.3% on the basis of their respective means while vBMD indicated no change. When a variation of 1 SD was observed in BA at the lateral spine, BMC, aBMD and vBMD correspondingly changed by 13.8%, 4.4% and 1.73% on the basis of their respective means. Through an intercomparison among large, intermediate and small BA groups, significant differences were found in the means of subject's height, weight, BMC and aBMD at the PA and lateral spine as well as the detection rate of osteoporosis by aBMD (p=0.000). Detection rates of osteoporosis by aBMD at the PA, lateral spine and vBMD in healthy pre-menopausal women aged from 40 years to 56 years were 4.5%, 16.4% and 9.7%, respectively, in the small BA group; 1.3%, 6.4% and 7.3%, respectively, in the intermediate BA group; and 0, 0 and 5.5%, respectively, in the large BA group. No significant differences were found in the detection rates of osteoporosis by vBMD among the groups. The results of multiple linear regression revealed that the major factors influencing BA of the lumbar spine was height. In healthy pre-menopausal women of the same race and age, the BA size of the lumbar spine would have significant influence upon aBMD and the diagnosis of osteoporosis, i.e. the larger the BA, the greater the aBMD and the lower the osteoporosis detection rate while conversely, the smaller the BA, the smaller the aBMD and the higher the osteoporosis detection rate. Though vBMD does not change with BA sizes of the lumbar spine, it is a sensitive marker for diagnosing osteoporosis.