Rate of forearm bone loss is associated with an increased risk of fracture independently of bone mass in postmenopausal women: the OFELY study

Genetic influences on bone loss in the San Antonio Family Osteoporosis study

The genetic contribution to age-related bone loss is not well understood. We estimated that genes accounted for 25-45% of variation in 5-year change in bone mineral density in men and women. An autosome-wide linkage scan yielded no significant evidence for chromosomal regions implicated in bone loss.

INTRODUCTION

The contribution of genetics to acquisition of peak bone mass is well documented, but little is known about the influence of genes on subsequent bone loss with age. We therefore measured 5-year change in bone mineral density (BMD) in 300 Mexican Americans (>45 years of age) from the San Antonio Family Osteoporosis Study to identify genetic factors influencing bone loss.

METHODS

Annualized change in BMD was calculated from measurements taken 5.5 years apart. Heritability (h(2)) of BMD change was estimated using variance components methods and autosome-wide linkage analysis was carried out using 460 microsatellite markers at a mean 7.6 cM interval density.

RESULTS

Rate of BMD change was heritable at the forearm (h(2) = 0.31, p = 0.021), hip (h(2) = 0.44, p = 0.017), spine (h(2) = 0.42, p = 0.005), but not whole body (h(2) = 0.18, p = 0.123). Covariates associated with rapid bone loss (advanced age, baseline BMD, female sex, low baseline weight, postmenopausal status, and interim weight loss) accounted for 10% to 28% of trait variation. No significant evidence of linkage was observed at any skeletal site.

CONCLUSIONS

This is one of the first studies to report significant heritability of BMD change for weight-bearing and non-weight-bearing bones in an unselected population and the first linkage scan for change in BMD.

Evaluating bone health in women with oestrogen receptor positive breast cancer (ERBC) starting aromatase inhibitors

AIMS

There is an increase in fractures in women with oestrogen receptor positive breast cancer (ERBC) particularly those taking aromatase inhibitors (AIs). How to identify women at osteoporosis risk, assess bone health and who to treat, are questions not adequately answered by previous studies.

METHODS

We present an audit of osteoporosis risk factors, bone mineral density (BMD) measurement and other data relevant to bone health (falls and laboratory tests) in 85 women with ERBC starting AIs.

RESULTS

Only 9/85 (11%) women overall and only 2/13 with previous peripheral fragility fractures had osteoporosis. Of note, secondary hyperparathyroidism was present in 40% of women <60 years; 67% of women 60-69 years and 75% of women >70 years.

CONCLUSIONS

Reliance on BMD alone to guide decisions for osteoporosis prevention treatment in those taking AIs would lead to few women being treated. Osteoporosis risk in women taking AIs is likely influenced by factors other than those encompassed by BMD alone.

Bone mass and architecture determination: state of the art

Bone fracture occurs when the bone strength (i.e. the ability of the bone to resist a force) is less than the force applied to the bone. In the elderly, falls represent the more severe forces applied to bone. Bone density is a good marker of bone strength, and has been used widely in this respect. Nevertheless, many aspects of bone strength cannot be explained by bone density alone. For this reason there has been increasing interest in studying architectural parameters of bone, beyond bone density, which may affect bone strength. Macro-architectural parameters include e.g. bone size and geometry assessed with techniques such as radiography, dual-energy x-ray absorptiometry (DXA), peripheral quantitative computed tomography (QCT), computed tomography (CT) and magnetic resonance imaging (MRI). Micro-architectural parameters include fine cortical and trabecular structural detail which can be evaluated using high-resolution imaging techniques such as multidetector CT, MRI, and high-resolution peripheral QCT. These techniques are providing a great deal of new information on the physiological architectural responses of bone to aging, weightlessness, and treatment. This will ultimately lead to the prediction of fracture risk being improved through a combined assessment of bone density and architectural parameters.

Bone mineral density changes during the menopause transition in a multiethnic cohort of women

CONTEXT

Rates of bone loss across the menopause transition and factors associated with variation in menopausal bone loss are poorly understood.

OBJECTIVE

Our objective was to assess rates of bone loss at each stage of the transition and examine major factors that modify those rates.

DESIGN, SETTING, AND PARTICIPANTS

We conducted a longitudinal cohort study of 1902 African-American, Caucasian, Chinese, or Japanese women participating in The Study of Women's Health Across the Nation. Women were pre- or early perimenopausal at baseline.

OUTCOME MEASURE

We assessed bone mineral density (BMD) of the lumbar spine and total hip across a maximum of six annual visits.

RESULTS

There was little change in BMD during the pre- or early perimenopause. BMD declined substantially in the late perimenopause, with an average loss of 0.018 and 0.010 g/cm2.yr from the spine and hip, respectively (P<0.001 for both). In the postmenopause, rates of loss from the spine and hip were 0.022 and 0.013 g/cm2.yr, respectively (P<0.001 for both). During the late peri- and postmenopause, bone loss was approximately 35-55% slower in women in the top vs. the bottom tertile of body weight. Apparent ethnic differences in rates of spine bone loss were largely explained by differences in body weight.

CONCLUSIONS

Bone loss accelerates substantially in the late perimenopause and continues at a similar pace in the first postmenopausal years. Body weight is a major determinant of the rate of menopausal BMD loss, whereas ethnicity, per se, is not. Healthcare providers should consider this information when deciding when to screen women for osteoporosis.

Prediction of bone loss using biochemical markers of bone turnover

The association between baseline levels of eleven bone turnover markers and 5-year rate of bone density change was prospectively studied in a population-based sample of 601 75-year-old women. Several bone formation and resorption markers as well as urinary osteocalcin were modestly correlated to rate of bone density change.

INTRODUCTION

Prediction of bone loss by bone turnover markers (BTMs) has been investigated with conflicting results. There is limited information in the elderly.

METHODS

Eleven bone turnover markers were analyzed in 75-year old women in the OPRA study (n = 601) and compared to the 5-year change of areal bone mineral density (aBMD) in seven skeletal regions.

RESULTS

Annual aBMD change varied between +0.4% (spine) and -2.0% (femoral neck). Significant associations (p < 0.01) were found for four different serum osteocalcins (S-OCs) (standardized regression coefficient -0.20 to -0.22), urinary deoxypyridinoline (-0.19), serum TRACP5b (-0.19), serum CTX-I (-0.21), two of the three urinary osteocalcins (U-OCs) (-0.16) and aBMD change of the leg region (derived from the total body measurement). After adjustment for baseline aBMD, associations were found for all S-OCs (-0.11 to -0.16), two of the three U-OCs (-0.14 to -0.16) and aBMD change at the total hip, and for three of the four S-OCs (-0.14 to -0.15), S-TRACP5b (-0.11), two of the three U-OCs (-0.14 to -0.15) and aBMD change at the femoral neck. There were no significant results concerning aBMD change at the spine.

CONCLUSION

This study indicates that BTMs are correlated with aBMD loss in some skeletal regions in elderly women.

Associations of vitamin D status with bone mineral density, bone turnover, bone loss and fracture risk in healthy postmenopausal women. The OFELY study

INTRODUCTION

Vitamin D status is considered as an important determinant of bone health but supplementation trials with vitamin D(3) have yielded conflicting results. The aim of this study was to investigate the associations between serum 25-hydroxyvitamin D (25-OH D), bone turnover markers, bone mineral density (BMD), radius bone loss and incidence of fracture in postmenopausal women.

METHODS

669 postmenopausal women (mean age: 62.2 years) belonging to a population-based cohort were followed prospectively for a median of 11.2 years. At baseline, 25-OH D levels, BMD, bone turnover markers and clinical risk factors of osteoporosis were assessed. BMD loss at the radius was estimated by annual measurements of BMD and all incident fractures which occurred in 134 women were confirmed by radiographs.

RESULTS

73% and 35% of women had serum 25-OH D levels below 75 and 50 nmol/l which correspond respectively to the median and lowest optimal values recently proposed for fracture prevention. 11% of women had levels below 30 nmol/l. Serum 25-OH D correlated modestly with intact PTH (r(2)=0.023, p<0.0001), but not with bone turnover markers or BMD at the hip and radius after adjustment for age. When levels of 25-OH D were considered as a continuous variable, there was no significant association between 25-OH D levels and radius BMD loss or fracture risk. After adjustment for age, there was no significant difference in incidence of fracture, BMD, radius BMD loss, bone turnover markers, grip strength and the percentage of fallers in the previous year between women with 25-OH D levels below or above 75, 50 or 30 nmol/l.

CONCLUSIONS

In a population of home-dwelling healthy postmenopausal women with few of them with severe vitamin D deficiency, vitamin D status may not be an important determinant of bone health.

Canadian Aboriginal women have a higher prevalence of vitamin D deficiency than non-Aboriginal women despite similar dietary vitamin D intakes

Canadian Aboriginal women have high rates of bone fractures, which is possibly due to low dietary intake of minerals or vitamin D. This study was undertaken to estimate dietary intake of calcium and vitamin D by designing a culturally appropriate dietary survey instrument and to determine whether disparities exist between Aboriginal and white women. After validation of a FFQ, 183 urban-dwelling and 26 rural-dwelling Aboriginal women and 146 urban white women completed the validated FFQ and had serum 25-hydroxyvitamin D [25(OH)D] measured. Urban Aboriginal women had lower (P=0.0004) intakes of total dietary calcium than urban white women; there was no difference in rural Aboriginal women. Only a minority of all women met the adequate intake (AI) for calcium intake. Ethnicity did not affect total vitamin D intake; however, rural Aboriginal women consumed all of their dietary vitamin D from food sources, which was more (P<0.03) than both urban Aboriginal and white women. Rural and urban Aboriginal women had lower (P<0.0004) serum 25(OH)D than urban white women. We found that 32% of rural Aboriginal, 30.4% of urban Aboriginal, and 18.6% of urban white women were vitamin D deficient, with serum 25(OH)D concentrations<37.5 nmol/L. The high prevalence of vitamin D deficiency among Aboriginal women, combined with lower dietary intake of calcium, especially in older women, likely contributes to the higher incidence of fracture in this population.

Thiazolidinedione use and bone loss in older diabetic adults

CONTEXT

Activation of peroxisome proliferator-activated receptor-gamma by thiazolidinediones (TZDs) results in lower bone mass in mice.

OBJECTIVE

The objective of the study was to determine whether TZD use is associated with changes in bone mineral density (BMD) in older adults with type 2 diabetes.

DESIGN

We analyzed 4-yr follow-up data from the Health, Aging, and Body Composition observational study.

SETTING

The study was conducted in a general community.

PATIENTS

White and black, physically able men and women, aged 70-79 yr at baseline with diabetes defined by self-report, use of hypoglycemic medication, elevated fasting glucose (>/=126 mg/dl), or elevated 2-h glucose tolerance test (>/=200 mg/dl) participated in the study.

MAIN OUTCOME MEASURES

Whole-body, lumbar spine (derived from whole body), and hip BMD were measured by dual-energy x-ray absorptiometry at 2-yr intervals.

RESULTS

Of 666 diabetic participants, 69 reported TZD use at an annual visit, including troglitazone (n = 22), pioglitazone (n = 30), and/or rosiglitazone (n = 31). Those with TZD use had higher baseline hemoglobin A(1c) and less weight loss over 4 yr but similar baseline BMD and weight than others with diabetes. In repeated-measures models adjusted for potential confounders associated with TZD use and BMD, each year of TZD use was associated with greater bone loss at the whole body [additional loss of -0.61% per year; 95% confidence interval (CI) -1.02, -0.21% per year], lumbar spine (-1.23% per year; 95% CI -2.06, -0.40% per year), and trochanter (-0.65% per year; 95% CI -1.18, -0.12% per year) in women, but not men, with diabetes.

CONCLUSION

These observational results suggest that TZDs may cause bone loss in older women. These results need to be tested in a randomized trial.

Disc space narrowing as a new risk factor for vertebral fracture: the OFELY study

OBJECTIVE

In a previous cross-sectional analysis, we found a positive association between disc space narrowing (DSN) and vertebral fracture. The aim of the present study was to analyze prospectively the risk of vertebral and nonvertebral fractures in women with spine osteoarthritis (OA).

METHODS

Using radiographs, spine OA was evaluated in 634 postmenopausal women from the OFELY (Os des Femmes de Lyon) cohort (mean+/-SD age 61.2+/-9 years). Prevalence and severity of spine OA were assessed by scoring osteophytes and DSN. Incidental clinical fractures were prospectively registered during annual followup, and vertebral fractures were evaluated by radiography every 4 years.

RESULTS

During an 11-year followup, fractures occurred in 121 women, including 42 with vertebral fractures. No association was found between osteophytes and the risk of fracture. In contrast, DSN was associated with an increased risk of vertebral fractures but not of nonvertebral fractures. After adjusting for confounding variables, the presence of DSN was associated with a marked increased risk of vertebral fractures, with an odds ratio of 6.59 (95% confidence interval 1.36-31.9). In addition, 95% of incident vertebral fractures were located above the disc with the most severe narrowing.

CONCLUSION

This longitudinal study shows that, despite a higher bone mineral density (BMD), women with spine OA do not have a reduced risk of fracture and that DSN is significantly associated with vertebral fracture risk. The location of DSN and of incident vertebral fractures suggests that disc degeneration impairs the biomechanics of the above spine, which leads to the increased risk of vertebral fractures, independent of BMD. We suggest that DSN is a newly identified risk factor for vertebral fracture that should be taken into consideration when assessing vertebral fracture risk in postmenopausal women.

Bone fragility in men--where are we?

INTRODUCTION

This is a summary of several aspects of the epidemiology, pathogenesis and treatment arising directly and indirectly from the proceedings of the Third International Osteoporosis in Men meeting held in Genoa in May 2005. Advances in the study of bone fragility in men have taken place, but many challenges remain.

OBSERVATIONS

Although the epidemiology of hip fractures is well documented, the epidemiology of other non-vertebral fractures is less well defined even though these fractures contribute substantially to the global burden of fractures in men. The epidemiology of vertebral fragility fractures is derived mostly from cross sectional data. The comparable prevalence of vertebral fractures in men and women is likely to be misleading because of traumatic vertebral fractures that arise in young men. Prospective studies are needed to define the proportion of these fractures that are traumatic. After the age of 50 years, the incidence of vertebral fractures in men is about one third to one half of that in women. As in women, most vertebral and non-vertebral fragility fractures occur in persons without osteoporosis. Identifying these individuals is an unmet challenge. The absolute risk for fractures appears no different by sex in men and women of the same age and bone mineral density (BMD) so that the diagnostic threshold for osteoporosis in women can be used in men. Fracture risk varies around the world and is unlikely to be explained solely by variations in BMD, though there are few data comparing men and women of different races. Both the notion that men lose less bone than women from the endosteal envelope and that they gain more on the periosteal envelope during advancing age needs reassessment as recent evidence challenges these observations. Sex differences in the net gain and loss from these surfaces are likely to be site specific, and research is needed to specify this heterogeneity and the reasons for it. The independent and co-dependent effects of sex hormones and the growth hormone/insulin like growth factor 1 axis on periosteal and endosteal modeling and remodeling during growth as well as ageing are poorly defined. The anti-fracture efficacy and safety of androgens and other agents remain incompletely investigated in men.

CONCLUSION

A great deal of research is needed to advance our understanding of bone fragility in men.