Progressive loss of bone in the femoral neck in elderly people: longitudinal findings from the Dubbo osteoporosis epidemiology study

Prevention of hip fractures: drug therapy

Drug therapy to prevent hip fractures may be considered for postmenopausal women with low bone mass and elderly people with risk factors for hip fracture. As most hip fractures occur 25 years or more after menopause, drug therapy may have to be prescribed for many years to be effective. A preventative drug should be effective, safe, and without side effects. Estrogen therapy decreases bone loss and hip fracture incident, but the effect wears off when treatment is stopped. The positive effect of estrogens on cardiovascular disease should be balanced against the increased risk of breast cancer with long-term use. The newer bisphosphonates are potent inhibitors of bone resorption and decrease bone loss substantially. Again, the effect may wear off after the drug is stopped. The bisphosphonates appear to be safe, but long-term data are lacking. Calcium and/or vitamin D may prevent bone loss in late postmenopausal women and elderly people. The combination was shown to prevent hip fractures and other peripheral fractures in elderly nursing home residents. No single drug will be used more than 10-15 years. Therefore, a public health strategy should be developed with a logical sequence of drug and nondrug interventions for the successful prevention of hip fractures.

Evaluation of the risk of hip fracture

Hip fracture is the most serious complication of osteoporosis and the incidence is rising worldwide. Bone mineral density measurements can be used not only to diagnose osteoporosis at the hip, but also to give prognostic information on the lifetime risk of hip fracture. A number of additional risk factors enhance the ability of density measurements to assess risk. Candidates include markers of bone resorption, prior fragility fractures, hip axis length, and estimates of postural integrity, each of which improve prognostic value independently of bone mineral assessments. Their use in the stratification of risk will help define intervention thresholds for treatments and improve the design of population screening policies, particularly in elderly women in whom the burden of hip fracture is greatest.

Increased bone turnover in late postmenopausal women is a major determinant of osteoporosis

Changes of bone turnover with aging are responsible for bone loss and play a major role in osteoporosis. Although an increase of bone turnover has been documented at the time of menopause, the subsequent abnormalities of bone resorption and formation and their potential role in determining bone mass in the elderly have not been investigated. To address this issue, we have measured a battery of new sensitive and specific markers of bone turnover in a population-based study of 653 healthy women analyzed cross-sectionally, including 432 women postmenopausal from 1 to 40 years, and the data were correlated with bone mineral density (BMD) measured by dual-energy X-ray absorptiometry (DXA) at different skeletal sites. Bone formation was assessed by serum osteocalcin (OC), serum bone-specific alkaline phosphatase (B-ALP), serum C-propeptide of type I collagen (PICP), and bone resorption by the urinary excretion of two pyridinoline cross-linked peptides (NTX and CTX). Bone turnover increased in perimenopausal women with both irregular menses and elevated serum follicle stimulating hormone (FSH). Menopause induced a 37-52% and 79-97% increase in the bone formation and bone resorption marker levels, respectively (p < 0.0001 except for PICP). In postmenopausal women, bone formation markers did not decrease with age. When resorption markers were corrected by whole body bone mineral content (BMC), the fraction of bone resorbed per day was not correlated with age in postmenopausal women and remained elevated for up to 40 years after menopause. In premenopausal women, the bone turnover rate accounted for only 0-10% of the variation in whole body BMC, total hip, distal radius, and lumbar spine BMD. With increasing time after menopause, the importance of the bone turnover rate as a determinant of bone mass increased at all sites and accounted for up to 52% of the BMD variance in elderly women. Thus, in women 20 years or more postmenopause, bone turnover was higher in those in the lowest quartile than in those in the highest quartile of BMD. In elderly women, 20 years since menopause and over, but not in younger ones, serum PTH was negatively correlated with serum 25-hydroxyvitamin D (r = -0.22, p < 0.05) and explained only 5-8% of the bone turnover variance (p < 0.01-0.001). These data indicate that the overall rates of both bone formation and bone resorption remain high in elderly women. The rate of bone turnover appears to play an increasing role as a determinant of bone mass with increasing time since menopause with a high bone turnover rate being associated with a low bone mass. Thus assessing bone marker levels may be useful in the evaluation of osteoporosis risk. In elderly women, secondary hyperparathyroidism caused in part by reduced serum 25-hydroxyvitamin D appears to be a marginal determinant of an increased bone turnover rate.

Prevalent vertebral deformities: relationship to bone mineral density and spinal osteophytosis in elderly men and women

The aims of this study were to ascertain vertebral deformity prevalence in elderly men and women and to describe the association between bone mineral density (BMD) at the lumbar spine and femoral neck, severity of spinal degenerative disease and vertebral deformity prevalence. We performed standardized spinal radiographs in a random sample of 300 elderly men and women participating in the Dubbo Osteoporosis Epidemiology Study, a population-based study of fracture risk factors. Radiographs were read independently by masked observers for the prevalence of vertebral deformity and severity of osteophytosis. BMD was measured by dual-energy X-ray absorptiometry. The prevalence of vertebral deformities was critically dependent on the criterion used. The less strict criteria seemed to overestimate deformities at either end of the spine region analysed. However, irrespective of the criterion used, prevalence of deformity was higher in men than in women (25% vs 20% for the 3 SD criterion, 17% vs 12% for the 4 SD criterion and 27% vs 25% for the 25% criterion). Femoral neck BMD was more strongly associated with vertebral deformities than spinal BMD for the 25% criterion (OR/SD change in BMD 1.39 (p = 0.02) vs 1.20 (p = 0.19)), 3 SD criterion (OR/SD change in BMD 1.45 (p = 0.01) vs 1.10 (p = 0.34)) and 4 SD criterion (OR/SD change in BMD 1.98 (p = 0.0002) vs 1.68 (p = 0.008)). BMD was also more strongly associated with biconcave deformities than either wedge or crush deformities and more so in men than in women. Severity of spinal osteophytosis was not associated with vertebral deformity. In conclusion, femoral neck BMD is at least equivalent to the lumbar spine BMD in strength of association with prevalent vertebral fractures. Spinal osteophytosis falsely elevates BMD without a concomitant decrease in fracture risk, indicating that any interpretation of spinal BMD needs to be adjusted for osteophytosis. These findings support the use of femoral neck bone densitometry in older men and women. Moreover, these data indicate that current criteria for radiological assessment of vertebral deformity are sufficiently loose to include a substantial proportion of non-fractures in the elderly, with important implications for the design of clinical trials. However, irrespective of the criterion used, vertebral deformities in men are at least as common, if not more so, than in women, suggesting that vertebral osteoporotic fractures are overlooked in men.

The effect of smoking at different life stages on bone mineral density in elderly men and women

To assess the effect of smoking on bone mineral density (BMD) at different life stages, to examine whether the effect of smoking differs between men and women, and to discover whether its effect in women differs according to history of estrogen use, a cohort study was carried out with single cross-section measurement of BMD by single and dual photon absorptiometry. The setting was the Framingham Study, a population-based cohort study with over 40 years prospectively collected data on smoking. Subjects (n = 1164) consisted of cohort members participating in the 20th biennial Framingham examination (1988-1989). The measurements included in the study were BMD measured at the hip, spine and radius, smoking history ascertained at all Framingham Study examinations since 1948, and other factors affecting BMD (age, weight, estrogen use, caffeine use, alcohol use and physical activity). Neither current smoking, recent (last 10 years) smoking, nor early adulthood smoking resulted in significantly lower BMD at any skeletal site among women who had not taken estrogen. Among women who had taken estrogen, BMD at most sites was lower among current or recent smokers, although the small numbers of smokers made it difficult to find significant differences at all skeletal sites. Among men, a consistently lower BMD at all skeletal sites was observed for smokers regardless of when in their life they smoked (4-15.3% lower), although the effect of smoking during early adulthood was of a lesser magnitude (4-8% lower). Former male smokers who had quit < 10 years ago had lower BMD than men who had quit > or = 10 years ago. In conclusion, in women who had used estrogen, BMD was lower in current or recent smokers than it was in non-smokers. In men, smoking at any stage of life had adverse effects on the skeleton that was independent of weight, alcohol or caffeine use, implying other mechanisms for smoking's effect on bone.

Equivalent deficits in bone mass of the vertebral body and posterior processes in women with vertebral fractures: implications regarding the pathogenesis of spinal osteoporosis

Reduced bone mass of the spine in women with vertebral fractures is attributed to excessive trabecular bone loss from the vertebral body. However, the measurement obtained by posteroanterior (PA) scanning includes the posterior processes and the vertebral body, each comprising about 50% of the total vertebral mass. Thus, the deficit in bone mass by PA scanning may be due to deficits in one or both of these structures. We asked two questions: (1) In healthy women, is the age-related diminution in bone mass of the vertebral body greater than the diminution at the posterior processes? (2) In women with vertebral fractures, is the deficit in bone mass at the vertebral body, the fracture site in spinal osteoporosis, greater than at the posterior processes? Bone mass of the posterior processes and vertebral body of the third lumbar vertebra was measured by lateral scanning using dual-energy X-ray absorptiometry (DXA). Compared with 27 premenopausal women, deficits in 27 postmenopausal women at the posterior processes and vertebral body, respectively, were 35.9 +/- 3.7 and 25.2 +/- 4.1% (p < 0.05); t score, -1.5 +/- 0.2 and -1.1 +/- SD (p = 0.09). Compared with the postmenopausal (age-matched) women, deficits in 21 women with vertebral fractures at the posterior processes and vertebral body, respectively, were 22.6 +/- 4.9 and 24.5 +/- 8.3% (p = NS); Z score, -0.8 +/- 0.2 and -0.8 +/- 0.3 (p = NS). In vivo the bone mass of the vertebral body as a percentage of the whole vertebra was 45.7 +/- 0.1 in premenopausal women, 48.9 +/ 1.9 in postmenopausal women, 51.5 +/- 1.1 in women with low bone mass but no fractures, 52.7 +/- 2.4 in women with vertebral fractures, and 51.9 +/- 2.5% in vitro, based on autopsy specimens from 19 postmenopausal women aged 65 - 95 years. The lower spinal bone density measured using PA scanning in women with spine fractures may not be due to excessive or disproportionate trabecular bone loss from the vertebral body because comparable deficits are found at the posterior processes. Whether these deficits are due to reduced peak bone mass, trabecular bone loss, cortical bone loss, or varying combinations of these mechanisms remains to be established.

Hip and calcaneal bone loss increase with advancing age: longitudinal results from the study of osteoporotic fractures

It is uncertain whether or how rapidly elderly women continue to lose bone with advancing age. To determine rates of change in bone mass at the hip and at the calcaneus in elderly women and to compare these rates of change among estrogen users and nonusers, we prospectively measured rates of change in bone mineral density (BMD) at the total hip and its four subregions (mean +/- SD, 3.55 +/- 0.29 years between examinations) and at the calcaneus (mean +/- SD, 5.69 +/- 0.33 years between examinations) in 5689 community-dwelling white women aged 65 years or older at the baseline examination. The rate of decline in total hip BMD steadily increased from 2.5 mg/cm 2/year (95% confidence interval 2.0 to 2.9) in women 67-69 years old to 10.4 mg/cm 2/year in those aged 85 or older (95% confidence interval 8.4 to 12.4). The rate of bone loss also increased with aging at all subregions of the hip and at the calcaneus. The average loss of bone from the total hip is sufficient to increase the risk of hip fracture by 21% per 5 years in women aged 80 years or older. Compared with nonusers, current estrogen users had a 33% lower age-adjusted mean rate of loss at the total hip (2.9 vs 4.3 mg/cm 2/year, p < or = 0.0001) and a 35% lower age-adjusted mean rate of loss at the calcaneus (3.9 vs 6.0 mg/cm 2/year, p < or = 0.0001). The rate of bone loss in the hip and calcaneus steadily increases with advancing age in older women. Estrogen therapy may significantly decrease this loss. Efforts to understand and prevent bone loss should include elderly women.

Present and future of osteoporosis therapy

In the 50-year "modern" history of osteoporosis, there have been about 17 antifracture studies with sufficient attention to design to allow inference regarding efficacy. Antivertebral fracture efficacy has been reported with etidronate, estrogen patch, calcitonin, and 1,25-dihydroxyvitamin D. Two studies using fluoride were positive, and two were negative. Hip fractures have been neglected. One study showed efficacy of hip protectors, one showed efficacy of vitamin D and calcium in nursing home dwellers. The source of most hip fractures is the community. One community based antihip fracture efficacy study using annual injections of vitamin D was positive. There have been no antivertebral or antihip fracture studies in men, or in corticosteroid-related osteoporosis in men or women. Lack of independently repeated demonstration of efficacy, small fracture numbers, and data pooling in some of these (the best) studies leave great uncertainty. Estrogen and bisphosphonates appear to be the best options at this time. New data suggest that calcium supplementation is likely to reduce the rate of bone loss and perhaps reduce fracture rates. The challenge is to maintain and restore the constituents of bone mineral density (BMD), that is: to promote periosteal and endosteal bone formation; reduce endosteal bone resorption and cortical porosity; and increase trabecular thickness, number, and connectivity. There are many opportunities, for instance, intermittent parathyroid hormone (PTH) increases bone strength and, with estrogen, may increase connectivity. The anabolic effects of PTH may be partly mediated by IGF-1. IGF-1 increases periosteal, endosteal, and trabecular bone formation, cortical and trabecular width, and trabecular and endocortical connectivity.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevention and treatment of osteoporosis

Because the lifetime risk of fragility fracture for a 50-year-old Caucasian woman is about 40 per cent, a whole-life strategy of osteoporosis prevention is necessary. In childhood, primary prevention of osteoporosis is based on exercise and adequate dietary calcium. In women undergoing menopause, hormone replacement therapy administered for at least ten years remains the preventive treatment of choice, and is associated with a substantial reduction in vertebral and non-vertebral fractures. Intranasal salmon calcitonin and bisphosphonates are effective alternatives, but their effects on fracture rate and their long-term safety require further evaluation. Regarding the prevention of the late bone loss leading to senile osteoporosis, there is now evidence that the reduction of the secondary hyperparathyroidism induced by calcium and vitamin D insufficiencies through the administration of calcium and vitamin D supplements significantly decreases the hip fracture incidence. There is no general consensus about the efficacy of treatment for established osteoporosis with fractures. Fluoride salts have proven their direct stimulating effects on bone formation; dosage must be moderate, and the duration of treatment should be limited to 2-3 years in order not to impair the quality of the new bone. Cyclical therapy with etidronate induces beneficial effects on bone mass in the spine, but its effect on the vertebral fracture rate is not yet established. The new bisphosphonates seem to be promising for the management of osteoporosis. Several other agents such as growth factors, silicon derivatives and strontium salts are in various stages of testing. The new definition of osteoporosis proposed by a WHO study group, no longer based on the fracture but on a low bone mass, is of major interest, because it should make possible to have a more effective therapeutic approach, before the occurrence of an irreversible degree of bone loss.

The contribution of vitamin D receptor gene alleles to the determination of bone mineral density in normal and osteoporotic women

Bone mass and its mineral content are under genetic control. The vitamin D receptor (VDR) gene has been shown to be a major locus for genetic effects on bone mineral density (BMD), and polymorphisms in this gene accounted for a large proportion of genetic variance in BMD in an Australian population. In this study, we investigated whether similar associations are present in a North American population. We studied 139 normal healthy women (age 53.2 +/- 14.5, mean +/- SD) and 43 severely osteoporotic postmenopausal women (age 65.8 +/- 5.9). In the 127 of them with complete genetic studies, the distribution of genotypes, determined by polymerase chain reaction on leukocyte DNA samples, agreed closely with that in the Australian population. BMD was strongly related to age and weight, and, thus was adjusted for these parameters prior to genetic analysis. We found that age modulated the effect of VDR genotypes on femoral neck BMD (FN-BMD) (TaqI, p = 0.036; BsmI, p = 0.118; ApaI, p = 0.041) such that the effect of genotype was greatest among younger (premenopausal) women and declined with age so that there was no discernible difference by age 70. Among the younger women, a high FN-BMD was associated with the TT (or aa or bb) genotype while low FN-BMD was associated with the tt (or AA or BB) genotype.(ABSTRACT TRUNCATED AT 250 WORDS)

Efficacy of treatment of osteoporotic fractures

The efficacy of osteoporosis therapy can be considered at several different levels, ranging from the overall community to the individual patient. Efficacy has different connotations for each group within the community and for the individual, in whom life expectancy--among other parameters--is an important consideration. Some of the questions addressed in this article are the scope of the osteoporosis problem, how many people must be treated for prevention of one further fracture, whether there is a role for targeting likely high risk/high response groups, and what exactly is a successful outcome. Clearly, there are no ideal therapies as yet for osteoporosis, in the context of either prevention or treatment. Moreover, most studies have been performed in selected groups within the community, and the extrapolation to wider clinical subsets is not straightforward. For example, data are almost nonexistent for men or premenopausal women; also it is not clear whether studies on carefully selected healthy elderly women can be simply extrapolated to their less healthy cohorts. Similarly, studies using vertebral deformities as the primary endpoint may be difficult to relate to symptomatic vertebral fractures, and other peripheral fractures including proximal femur. Lastly, the efficacy of some treatments must be related to the risk of further fractures. Thus, many years of therapy may relate to prevention of perhaps only one symptomatic event, with equivocal cost-benefit for the individual. As new therapies are under development, these questions need to be addressed for the efficacy of osteoporosis therapy to be considered.

The dilemma of osteoporosis in men

Hip fractures in men account for one third of all hip fractures and have a higher mortality than in women. The age-specific incidence of hip fractures is increasing so that the public health burden will increase out of proportion to the burden imposed by the increase in the numbers of elderly men in the community. Vertebral fractures are a public health problem of lesser magnitude in terms of morbidity, mortality, and cost, but they are debilitating and are seen commonly in clinical practice. (Forearm fractures should probably not be regarded as a public health problem.) The pattern of earlier gain/later loss of bone during ageing in healthy men is well documented. Peak bone mass is higher in men than women because men have bigger bones. Peak bone density is the same. The absolute amount of trabecular bone lost at the spine and iliac crest during ageing is similar in men and women. Cortical bone loss is less in men. It is less because endocortical resorption is less, and periosteal formation is greater, in men. Bone loss may accelerate in elderly men and women (rather than decelerate), perhaps because endocortical resorption and increasing cortical porosity increase the effective surface available for resorption in cortical bone. Thus, bone fragility is less in men because (a) the cross-sectional surface of the vertebral body is larger; (b) trabecular bone loss is less as a percentage of the higher peak bone mass; (c) trabecular bone loss occurs by thinning rather than perforation; and (d) periosteal appositional growth compensates for endocortical resorption by maintaining the bending strength of bone. Reduced bone density in men with fractures may be due to reduced peak bone density and bone loss. As found in women with spine fractures, men with fractures have smaller bone size. Bone loss occurs by reduced bone formation and increased bone resorption. Loss of connectivity appears to predominate in men with vertebral fractures; trabecular thinning appears to predominate in men with hip fractures. Whether men with fractures have increased bone fragility due to reduced periosteal appositional growth during ageing is unknown. The age-related decline in testosterone, adrenal androgens, growth hormone, and insulin-like growth factor 1 may be concomitants of ageing or may contribute to reduced bone-formation and bone loss. Men with vertebral fractures may be more deficient in growth hormone and insulin-like growth factor 1. Thy often have illness, hypogonadism, or illnesses associated with hypogonadism that should be sought with a high index of suspicion.(ABSTRACT TRUNCATED AT 400 WORDS)