BMD at multiple sites and risk of fracture of multiple types: long-term results from the Study of Osteoporotic Fractures

Bone texture analysis on direct digital radiographic images: precision study and relationship with bone mineral density at the os calcis

Assessment of bone microarchitecture in complement to bone mineral density (BMD) exam could improve prediction of osteoporotic fractures. A high-resolution X-ray prototype was developed to assess microarchitecture quality. Images were obtained on os calcis; then, three texture parameters were calculated on the same region of interest (ROI): a fractal parameter, a run-length parameter, and a co-occurrence parameter. This work describes the reproducibility of this method. We also examine the relationship between texture parameters and BMD at a site-matched ROI. Measurements on the left heel were performed on 30 healthy women, on the same day, with repositioning for short-term precision error. An additional measurement was done at 1 week to evaluate mid-term precision error on 14 subjects. Os calcis images from 10 healthy women were used to evaluate both intra- and interobserver reproducibility. Thirty other healthy patients were measured successively on two similar devices for interprototype comparison. BMD and texture analyses of the left heel were obtained from 57 women. Short-term precision errors ranged 1.16-1.24% according to the texture parameter. Mid-term precision error was slightly higher than short-term precision for the mean Hurst exponent parameter. Comparisons of texture parameters and BMD at a site-matched ROI on the os calcis showed no significant relationships. The results also show that the use of this high-resolution digital X-ray device improves the reproducibility of parameter measurement compared to the indirect digitization of radiologic films previously used.

Effectiveness of bone density measurement for predicting osteoporotic fractures in clinical practice

CONTEXT

Bone density measurement with dual-energy x-ray absorptiometry is widely used for fracture risk assessment. It has not been established that published gradients of fracture risk from study populations can be directly applied to clinical populations.

OBJECTIVE

The objective of the study was to assess osteoporotic fracture prediction with dual-energy x-ray absorptiometry in a large clinical cohort.

DESIGN

This was a historical cohort study (mean observation period 3.2 +/- 1.5 yr).

PATIENTS

The study population was drawn from the population-based database of the Manitoba Bone Density Program. Analyses were limited to women aged 50 yr or older at baseline (n = 16,505).

MAIN OUTCOME MEASURE

Each subject's longitudinal health service record was assessed for the presence of nontrauma fracture codes (hip, spine, wrist, and humerus) after bone density testing. Age-adjusted hazard ratios for fracture were derived from Cox proportional hazards models.

RESULTS

Site-specific and overall fracture rates were significantly associated with each site of bone density measurement (all P < 0.00001). The 95% confidence intervals overlapped those from a widely cited metaanalysis of fracture prediction from different sites. Although fracture prediction was not significantly different between the three hip measurement sites, each hip site was better than the lumbar spine for predicting overall fractures (nonoverlapping 95% confidence intervals). The manufacturer sd (equivalent to a unit change in T-score) resulted in a significantly smaller gradient of risk for the spine than when the population sd was used.

CONCLUSIONS

Bone density measurements are effective for predicting fractures in clinical practice. However, hip measurements were superior to the spine in overall osteoporotic fracture prediction.

Structural and remodeling indices in the cancellous bone of the proximal femur across adulthood

Fragility fractures, including fractures of the femoral neck, result from reductions in the amount, quality and architecture of bone. However, investigations of the underlying structural changes that might predispose to fracture have been largely limited to skeletal sites that do not fracture, such as the iliac crest (IC). The aim of this study was to use histomorphometry to map changes in the architecture and the static remodeling indices of cancellous bone, as a function of age and sex, in bone samples taken from the intertrochanteric (IT) region of the proximal femur at routine autopsy (18-88 years of age). Bone samples for histology were processed from 10-mm cubes of IT cancellous bone. Histomorphometry was performed using an ocular-mounted 10 x 10 graticule at a magnification of x100. An age-dependent decrease in trabecular bone volume was observed in both females and males, as expected (r=-0.75 and r=-0.63, p<0.001, respectively). The underlying mechanisms for bone turnover appeared to be different between males and females. Thus, while the static index of bone resorption (ES/BV) was positively age-dependent in males and females (p<0.001, p<0.03, respectively), the index of bone formation (OS/BV) correlated positively with age in the female group only (p<0.001 vs. NS). Perhaps reflecting an increase in bone formation in older females, the OS/ES ratio was greater in older females than younger females or males. Surprisingly, while resorption indices increased in older males compared with their younger counterparts, bone formation indices increased only in the older female cohort. The IT region in the proximal femur is adjacent to the site commonly involved in fragility fracture. With the limitation that these results describe cross-sectional data, they provide useful insights into changes in the cancellous bone structure and at the bone surface of females and males over the age range of 20-90 years, at a clinically relevant skeletal site.

Role of dual-energy X-ray absorptiometry in the diagnosis and treatment of osteoporosis

Dual energy X-ray absorptiometry (DXA) measurements of spine and hip bone mineral density (BMD) (referred to here as central DXA) have an important role as a clinical tool for the evaluation of individuals at risk of osteoporosis, and in helping clinicians give advice to patients about the appropriate use of antifracture treatment. Compared with alternative bone densitometry techniques such quantitative computed tomography (QCT), peripheral DXA (pDXA) and quantitative ultrasound (QUS), central DXA has a number of significant advantages that include a consensus that BMD results can be interpreted using the World Health Organization (WHO) T-score definition of osteoporosis, a proven ability to predict fracture risk, and proven effectiveness at targeting antifracture treatments. This review article discusses the evidence for these and other advantages of central DXA, including its role in the new WHO algorithm for treating patients on the basis of individual fracture risk.

Prediction and discrimination of osteoporotic hip fracture in postmenopausal women

Osteoporotic hip fractures increase dramatically with age and are responsible for considerable morbidity and mortality. Several treatments to prevent the occurrence of hip fracture have been validated in large randomized trials and the current challenge is to improve the identification of individuals at high risk of fracture who would benefit from therapeutic or preventive intervention. We have performed an exhaustive literature review on hip fracture predictors, focusing primarily on clinical risk factors, dual X-ray absorptiometry (DXA), quantitative ultrasound, and bone markers. This review is based on original articles and meta-analyses. We have selected studies that aim both to predict the risk of hip fracture and to discriminate individuals with or without fracture. We have included only postmenopausal women in our review. For studies involving both men and women, only results concerning women have been considered. Regarding clinical factors, only prospective studies have been taken into account. Predictive factors have been used as stand-alone tools to predict hip fracture or sequentially through successive selection processes or by combination into risk scores. There is still much debate as to whether or not the combination of these various parameters, as risk scores or as sequential or concurrent combinations, could help to better predict hip fracture. There are conflicting results on whether or not such combinations provide improvement over each method alone. Sequential combination of bone mineral density and ultrasound parameters might be cost-effective compared with DXA alone, because of fewer bone mineral density measurements. However, use of multiple techniques may increase costs. One problem that precludes comparison of most published studies is that they use either relative risk, or absolute risk, or sensitivity and specificity. The absolute risk of individuals given their risk factors and bone assessment results would be a more appropriate model for decision-making than relative risk. Currently, a group appointed by the World Health Organization and lead by Professor John Kanis is working on such a model. It will therefore be possible to further assess the best choice of threshold to optimize the number of women needed to screen for each country and each treatment.

Association between prior non-spine non-hip fractures or prevalent radiographic vertebral deformities known to be at least 10 years old and incident hip fracture

In this large cohort of elderly women, prior non-spine non-hip fractures and radiographic vertebral deformities >10 years old were modestly associated with incident hip fracture, but the excess risks of hip fracture attributable to those prior fractures and deformities seem to wane over time.

INTRODUCTION

Whereas prior clinical fractures and prevalent radiographic vertebral deformities are well-documented predictors of incident hip fracture, the excess risks of incident fractures attributable to those prior fractures and deformities may decrease over time. Current guidelines regarding the assessment of fracture risk do not consider elapsed time since prior fracture or ascertainment of radiographic vertebral deformity.

MATERIALS AND METHODS

We ascertained self-reported history of prior clinical fractures and calcaneal and total hip bone BMD and performed lateral spine radiographs in a cohort of 9516 community-dwelling elderly women who had not had a prior hip fracture. We prospectively followed them to assess incident hip fracture. Prevalent radiographic vertebral deformities were identified at baseline using morphometry, and incident hip fractures were confirmed by review of radiographic reports during three follow-up periods (0-5, >5-10, and >10 years after baseline exam).

RESULTS

Among women who survived for 10 or more years after the baseline exam without having had a hip fracture, a history of non-spine non-hip fracture since age 50 reported at the baseline study examination was associated with a 21% age- and calcaneal BMD-adjusted excess risk (hazard ratio [HR], 1.21; 95% CI, 1.01-1.45) for subsequent incident hip fracture. Baseline radiographic vertebral deformity was associated with a 41% age- and BMD-adjusted excess risk (HR, 1.41; 95% CI, 1.15-1.73) of hip fracture after 10 years of follow-up. In comparison, the age- and BMD-adjusted HRs of incident hip fracture during the first 5 years of follow-up associated with prior non-spine non-hip fractures reported at the baseline study exam and prevalent radiographic vertebral deformities were 1.70 (95% CI, 1.30-2.22) and 2.10 (95% CI, 1.58-2.78), respectively.

CONCLUSIONS

Self-reported prior non-spine non-hip fractures and prevalent radiographic vertebral deformities known to be at least 10 years old are modestly associated with incident hip fracture. The association between these predictor fractures and subsequent hip fractures seems to wane with increased time after ascertainment of the predictor fracture. Hip fracture risk assessment strategies incorporating prior fracture history should also consider elapsed time since those prior fractures.

Relationship between moderate to severe kidney disease and hip fracture in the United States

People with ESRD are at a high risk for hip fracture. However, the effect of moderate to severe chronic kidney disease (CKD) on hip fracture risk has not been well studied. As part of the Third National Health and Nutrition Examination Survey, information on both kidney function and history of hip fracture was obtained. This survey is a complex, multistage, probability sample of the US noninstitutionalized civilian population and was conducted between 1988 and 1994. A history of hip fracture was identified from the response to a questionnaire that was administered to all participants. There were 159 cases of hip fracture. There was a significantly increased likelihood of reporting a hip fracture in participants with estimated GFR <60 ml/min (odds ratio [OR] 2.12; 95% confidence interval [CI] 1.18 to 3.80). In younger participants (aged 50 to 74 yr), the prevalence of CKD was approximately three-fold higher in those with a history of hip fracture versus in those without a history of hip fracture (19.0 versus 6.2%, respectively; P = 0.04). In multivariate logistic regression analysis, only the presence of CKD (OR 2.32; 95% CI 1.13 to 4.74), a reported history of osteoporosis (OR 2.52; 95% CI 1.08 to 5.91), and low physical activity levels (OR 2.10; 95% CI 1.03 to 4.27) were associated with a history of hip fracture. There is a significant association between hip fracture and moderate to severe degrees of CKD, particularly in younger individuals, that is independent of traditional risk factors for hip fracture.

SULT1E1 genetic polymorphisms modified the association between phytoestrogen consumption and bone mineral density in healthy Korean women

Sulfotransferase 1E1 (SULT1E1) catalyze estrogen into sulfate conjugation and is involved in the metabolism of phytoestrogen. A community-based cross-sectional study was conducted on 397 Korean women, to evaluate the association between genetic polymorphisms of SULT1E1 and bone mineral density (BMD) and the combined effect of the genetic polymorphism and phytoestrogen intake for BMD in Korean women. BMDs of the distal radius and the calcaneus were measured by dual-energy X-ray absorptiometry. Genotypes of SULT1E1 IVS1-447 C>A, IVS4-1653 T>C, and *959 G>A were determined by the 5'-nuclease assay (TaqMan). Phytoestrogen intake was estimated by a food-frequency questionnaire validated against multiple 24-hour recalls. Women with the SULT1E1 *959 GG genotype had a 4.5% lower BMD at the distal radius (P (trend )= 0.05) and a 7.9% lower BMD at the calcaneus compared to those with AA genotype (P (trend) < 0.01), whereas the SULT1E1 IVS1-447 CC genotype and IVS4-1653 TT genotype were not associated with BMD. There was no significant trend of BMD with the numbers of CTG-containing haplotypes, but calcaneal BMDs significantly differed between SULT1E1 CTA-CTA haplotype and CTG-CCA haplotype (P < 0.05). When stratified by SULT1E1 genotype, the correlation between phytoestrogen consumption and BMD at the calcaneus was noteworthy in women with SULT1E1 *959 GG genotype (r = 0.25, P = 0.01) or SULT1E1 IVS 4-1653 TT genotype (r = 0.15, P = 0.02). This trend remained significant only in postmenopausal women (r = 0.36, P = 0.01) after multiple testing was corrected by the false discovery rate method. In conclusion, the genetic polymorphism of SULT1E1 *959 G > A was associated with BMD at the distal radius and calcaneus, and the association between phytoestrogen consumption and calcaneal BMD might be modified by this genetic polymorphism.

Incidence and risk factors for vertebral fracture in women and men: 25-year follow-up results from the population-based Framingham study

This study evaluates baseline characteristics of 704 women and men in the Framingham Study with respect to long-term risk of incident vertebral fracture. Incidence was 24% in women and 10% in men. Few factors in middle-aged persons, except prevalent (moderate) fracture and alcohol consumption (in men), predicted long-term incidence of vertebral fracture.

INTRODUCTION

We studied potential risk factors in women and men in middle adult years to help identify individuals at increased long-term risk of vertebral fracture in advanced age.

MATERIALS AND METHODS

Participants included Framingham cohort members who underwent radiographic examinations at baseline in 1967-1969 (mean age, 53 years) and follow-up in 1992-1993. Semiquantitative methods were used to determine incident fracture, defined as any vertebral body graded normal at baseline and at least mildly deformed (20-25% reduction or more in any vertebral height) at follow-up. Information on potential risk factors was obtained from examinations conducted at or before baseline radiography.

RESULTS

Prevalence of vertebral fracture was similar (14%) in women and men, although incidence was greater in women (24%) than men (10%). Alcohol consumption increased fracture risk in men. Multivariable-adjusted ORs increased from 1.78 in men who consumed 1-3 oz of alcohol per week in middle-age years to 4.61 in those with intakes of > or =4 oz/week (trend, P = 0.0099). Age, height, weight, grip strength, physical activity, metacarpal cortical area, and estrogen use (in women) had little or no influence on cumulative incidence of vertebral fracture. Results were similar when fracture was restricted to (at least) moderate severity; however, participants with moderate to severe fracture prevalent at baseline had five times the incidence of moderate to severe fracture during follow-up compared with those without moderately to severe prevalent fractures.

CONCLUSIONS

Few factors in middle-aged persons, except prevalent fracture and alcohol consumption (in men), predict long-term incidence of vertebral fracture. The explanation underlying this finding is not readily apparent, however, risk factors for vertebral fracture may be more relevant to older individuals, with respect to short-term fracture risk, than to middle-aged adults in relation to long-term risk with aging.

Prevention and treatment of osteoporosis in inflammatory bowel disease

The following are guidelines for evaluation and consideration for treatment of patients with inflammatory bone disease (IBD) after bone mineral density (BMD) measurements. The Crohn's & Colitis Foundation of America (CCFA) has indicated that its recommendations are intended to serve as reference points for clinical decision-making, not as rigid standards, limits, or rules. They should not be interpreted as quality standards.

Identification of a quantitative trait locus on rat chromosome 4 that is strongly linked to femoral neck structure and strength

Risk factors for osteoporotic hip fracture include reduced bone mineral density and poor structure of the femoral neck, both of which are heritable traits. Previously, we showed that despite similar body size, Fischer 344 (F344) rats have significantly different skeletal traits compared with Lewis (LEW) rats. To identify a gene or genes regulating fracture risk at the femoral neck, we mapped quantitative trait loci (QTL) for femoral neck density and structure phenotypes using a 595 F2 progeny derived from the inbred F344 and LEW strains of rats. Femoral neck phenotypes included volumetric bone mineral density (vBMD), neck width, femoral neck cross-sectional area and polar moment of inertia (Ip). A 20-cM genome-wide scan was performed using 118 microsatellite markers and linkage analysis was conducted to identify chromosomal regions harbor QTL for femoral neck phenotypes. Strong evidence of linkage (P<0.01) to femoral neck vBMD was observed on chromosomes (Chrs) 1, 2, 4, 5, 7, 10 and 15. QTL affecting femoral neck structure and biomechanical properties were detected only on Chr 4 where the F344 alleles were shown to improve femoral neck structure, whereas these alleles had no effect on bone measurements at the lumbar spine and only modest effects at the femoral midshaft. In contrast, QTL on Chrs 1, 2 and 10 affected multiple skeletal sites. Several QTL regions in this study are homologous to human chromosomal regions, where linkage to femoral neck and related phenotypes has been reported previously. These findings represent an important first step in localizing and identifying genes that influence hip fragility.

[Secondary screening for osteoporosis in patients admitted for hip fracture to a rehabilitation center. Results of a survey]

GOALS

To determine prevalence, risk factors and treatment of osteoporosis in patients with hip fracture observed in a rehabilitation ward.

BACKGROUND

Hip fractures are associated with up to 20% excess mortality in the first year after fracture and cause functional disability in most survivors. Despite available risk indices and physician information, osteoporosis is still underdiagnosed and undertreated.

METHOD

We obtained history, clinical and biological data, and bone density (BD) data in 41 patients admitted with hip fracture to a rehabilitation care centre.

RESULTS

Only 3 patients had known osteoporosis. Although 50% had at least 1 clinical risk factor, all patients showed osteopenic BD scores and 68% had osteoporotic scores; only one was correctly treated.

DISCUSSION

As with international studies, our study shows that osteoporosis is underdiagnosed. Risk assessment tools allow for routine screening and preventive measures incorporated into standard care practice. The prevention of osteoporotic fracture can be promoted in rehabilitation centres.

The DXL Calscan heel densitometer: evaluation and diagnostic thresholds

The DXL Calscan (Demetech AB) is a new dual energy X-ray absorptiometry device for determining heel bone mineral density (BMD). The system is based on the standard technique of dual energy X-ray absorptiometry (DXA), using a fan beam configuration, but introduces an additional laser measurement of heel thickness intended to improve accuracy. We have examined the utility, in vitro and in vivo performance of the DXL Calscan and established triage thresholds based on the UK's National Osteoporosis Society guidelines on peripheral densitometry. The Calscan proved convenient, easy to use and was stable over time and within a range of operating temperatures. Short-term in vitro precision as %CV, with phantom repositioning, was 0.75% and long term precision 0.73%. Precision in vivo, determined from duplicate right heel scans of 67 subjects, was 1.19%. Effective radiation dose to the patient was <0.1 microSv per scan. 140 white females (70 osteoporotic and 70 non-osteoporotic), aged 55-70 years underwent scans of both heels. Subjects were defined as osteoporotic or non-osteoporotic on the basis of axial DXA (spine L2-L4 and total hip). Triage thresholds for reassurance-referral or referral-treatment were 0.391 g cm(-2) and 0.306 g cm(-2) for non-dominant and 0.395 g cm(-2), 0.294 g cm(-2) for dominant heel, respectively. The non-dominant heel proved slightly superior to the dominant for triage purposes. Of the seven non-osteoporotic subjects misclassified as osteoporotic by Calscan of either heel, six had severe axial osteopenia. If operated by trained personnel and used in appropriate populations exhibiting risk factors, the Calscan is well suited for use in the management of post-menopausal osteoporosis.

Calcium and vitamin D in the prevention and treatment of osteoporosis - a clinical update

Combined calcium and vitamin D supplementation is an essential component of the management of osteoporosis, supported by a strong scientific rationale. The types of individuals who should receive calcium and vitamin D supplements are those: (i) patients with documented osteoporosis receiving antiresorptive or anabolic treatment; (ii) patients receiving glucocorticoids; and (iii) individuals with or at high risk of calcium and/or vitamin D insufficiencies, in particular older women and men. This article describes the evidence base that supports targeting these groups. Benefits are most apparent when 800 IU day(-1) vitamin D is complemented with a dose of 1000-1200 mg day(-1) elemental calcium. Compliance is also key to optimizing clinical efficacy.

Addressing the musculoskeletal components of fracture risk with calcium and vitamin D: a review of the evidence

Osteoporotic fractures are an extremely common and serious health problem in the elderly. This article presents the rationale for calcium and vitamin D supplementation in the prevention and treatment of osteoporotic fractures and reviews the literature evidence on the efficacy of this strategy. Two musculoskeletal risk factors are implicated in osteoporotic fractures in the elderly: the loss of bone mass due to secondary hyperparathyroidism and the increased propensity to falls. Calcium and vitamin D reverse secondary hyperparathyroidism with resultant beneficial effects on bone mineral density (BMD). Additionally, calcium and vitamin D supplementation significantly improves body sway and lower extremity strength, reducing the risk of falls. The effects of combined calcium and vitamin D on parathyroid function and BMD provide a strong rationale for the use of this therapy in the prevention and treatment of osteoporosis and osteoporotic fractures. There is general agreement that, in patients with documented osteoporosis, calcium and vitamin D supplementation should be an integral component of the management strategy, along with antiresorptive or anabolic treatment. Frail elderly individuals constitute another major target population for calcium and vitamin D because evidence from randomized studies in institutionalized elderly subjects demonstrates that these supplements reduce osteoporotic fracture risk, particularly in the presence of dietary deficiencies. However, the results of trials in community-dwelling subjects have been equivocal. Within the primary-care setting, further research is required to establish appropriate target subgroups for calcium and vitamin D supplementation; overall, the data are consistent with a benefit individuals with insufficient calcium and/or vitamin D, although patients with documented osteoporosis will derive further benefit in terms of fracture prevention from the addition of an antiresorptive agent.

Management of osteoporosis in postmenopausal women

OBJECTIVE

To update the evidence-based position statement published by The North American Menopause Society (NAMS) in 2002 regarding the management of osteoporosis in postmenopausal women.

DESIGN

NAMS followed the general principles established for evidence-based guidelines to create this updated document. A panel of clinicians and researchers expert in the field of metabolic bone diseases and/or women's health were enlisted to review the 2002 NAMS position statement, compile supporting statements, and reach consensus on recommendations. The panel's recommendations were reviewed and approved by the NAMS Board of Trustees.

RESULTS

Osteoporosis, whose prevalence is especially high among elderly postmenopausal women, increases the risk of fractures. Hip and spine fractures are associated with particularly high morbidity and mortality in this population. Given the health implications of osteoporotic fractures, the primary goal of osteoporosis therapy is to prevent fractures, which is accomplished by slowing or stopping bone loss, maintaining bone strength, and minimizing or eliminating factors that may contribute to fractures. The evaluation of postmenopausal women for osteoporosis risk requires a medical history, physical examination, and diagnostic tests. Major risk factors for postmenopausal osteoporosis (as defined by bone mineral density) include advanced age, genetics, lifestyle factors (such as low calcium and vitamin D intake, smoking), thinness, and menopause status. The most common risk factors for osteoporotic fracture are advanced age, low bone mineral density, and previous fracture as an adult. Management focuses first on nonpharmacologic measures, such as a balanced diet, adequate calcium and vitamin D intake, adequate exercise, smoking cessation, avoidance of excessive alcohol intake, and fall prevention. If pharmacologic therapy is indicated, government-approved options are bisphosphonates, a selective estrogen-receptor modulator, parathyroid hormone, estrogens, and calcitonin.

CONCLUSIONS

Management strategies for postmenopausal women involve identifying those at risk of low bone density and fracture, followed by instituting measures that focus on reducing modifiable risk factors through lifestyle changes and, if indicated, pharmacologic therapy.

Half the burden of fragility fractures in the community occur in women without osteoporosis. When is fracture prevention cost-effective?

To determine the age- and BMD-specific burden of fractures in the community and the cost-effectiveness of targeted drug therapy, we studied a demographically well-categorized population with a single main health provider. Of 1224 women over 50 years of age sustaining fractures during 2 years, the distribution of all fractures was 11%, 20%, 33%, and 36% in those aged 50-59, 60-69, 70-79, and 80+ years, respectively. Osteoporosis (T score < -2.5) was present in 20%, 46%, 59%, and 69% in the respective age groups. Based on this sample and census data for the whole country, treating all women over 50 years of age in Australia with a drug that halves fracture risk in osteoporotic women and reduces fractures in those without osteoporosis by 20%, was estimated to prevent 18,000 or 36% of the 50,000 fractures per year at a total cost of $573 million (AUD). Screening using a bone mineral density of T score of -2.5 as a cutoff, misses 80%, 54%, 41%, and 31% of fractures in women in the respective age groups. An analysis of cost per averted fracture by age group suggests that treating women in the 50- to 59-year age group with osteoporosis alone costs $156,400 per averted fracture. However, in women aged over 80 years, the cost per averted fracture is $28,500. We infer that treating all women over 50 years of age is not feasible. Using osteoporosis and age (>60 years) as criteria for intervention reduces the population burden of fractures by 28% and is cost-effective but solutions to the prevention of the remaining 72% of fragility fractures remain unavailable.

Vertebral fracture risk reduction with strontium ranelate in women with postmenopausal osteoporosis is independent of baseline risk factors

Strontium ranelate (2 g/day) was studied in 5082 postmenopausal women. A reduction in incident vertebral fracture risk by 40% was shown after 3 years. This effect was independent of age, initial BMD, and prevalent vertebral fractures.

INTRODUCTION

Strontium ranelate is an orally active treatment able to decrease the risk of vertebral and hip fractures in osteoporotic postmenopausal women. The aim of this study was to assess the efficacy of strontium ranelate according to the main determinants of vertebral fracture risk: age, baseline BMD, prevalent fractures, family history of osteoporosis, baseline BMI, and addiction to smoking.

MATERIALS AND METHODS

We pooled data of two large multinational randomized double-blind studies with a population of 5082 (2536 receiving strontium ranelate 2 g/day and 2546 receiving a placebo), 74 years of age on average, and a 3-year follow-up. An intention-to-treat principle was used, as well as a Cox model for comparison and relative risks.

RESULTS

The treatment decreased the risk of both vertebral (relative risk [RR] = 0.60 [0.53-0.69] p < 0.001) and nonvertebral (RR = 0.85 [0.74-0.99] p = 0.03) fractures. The decrease in risk of vertebral fractures was 37% (p = 0.003) in women <70 years, 42% (p < 0.001) for those 70-80 years of age, and 32% (p = 0.013) for those > or = 80 years. The RR of vertebral fracture was 0.28 (0.07-0.99) in osteopenic and 0.61 (0.53-0.70) in osteoporotic women, and baseline BMD was not a determinant of efficacy. The incidence of vertebral fractures in the placebo group increased with the number of prevalent vertebral fractures, but this was not a determinant of the effect of strontium ranelate. In 2605 patients, the risk of experiencing a first vertebral fracture was reduced by 48% (p < 0.001). The risk of experiencing a second vertebral fracture was reduced by 45% (p < 0.001; 1100 patients). Moreover, the risk of experiencing more than two vertebral fractures was reduced by 33% (p < 0.001; 1365 patients). Family history of osteoporosis, baseline BMI, and addiction to smoking were not determinants of efficacy.

CONCLUSIONS

This study shows that a 3-year treatment with strontium ranelate leads to antivertebral fracture efficacy in postmenopausal women independently of baseline osteoporotic risk factors.

Genome-wide scan identified QTLs underlying femoral neck cross-sectional geometry that are novel studied risk factors of osteoporosis

A genome-wide screen was conducted using a large white sample to identify QTLs for FNCS geometry. We found significant linkage of FNCS parameters to 20q12 and Xq25, plus significant epistatic interactions and sex-specific QTLs influencing FNCS geometry variation.

INTRODUCTION

Bone geometry, a highly heritable trait, is a critical component of bone strength that significantly determines osteoporotic fracture risk. Specifically, femoral neck cross-sectional (FNCS) geometry is significantly associated with hip fracture risk as well as genetic factors. However, genetic research in this respect is still in its infancy.

MATERIALS AND METHODS

To identify the underlying genomic regions influencing FNCS variables, we performed a remarkably large-scale whole genome linkage scan involving 3998 individuals from 434 pedigrees for four FNCS geometry parameters, namely buckling ratio (BR), cross-sectional area (CSA), cortical thickness (CT), and section modulus (Z). The major statistical approach adopted is the variance component method implemented in SOLAR.

RESULTS

Significant linkage evidence (threshold LOD = 3.72 after correction for tests of multiple phenotypes) was found in the regions of 20q12 and Xq25 for CT (LOD = 4.28 and 3.90, respectively). We also identified eight suggestive linkage signals (threshold LOD = 2.31 after correction for multiple tests) for the respective geometry traits. The above findings were supported by principal component linkage analysis. Of them, 20q12 was of particular interest because it was linked to multiple FNCS geometry traits and significantly interacted with five other genomic loci to influence CSA variation. The effects of 20q12 on FNCS geometry were present in both male and female subgroups. Subgroup analysis also revealed the presence of sex-specific quantitative trait loci (QTLs) for FNCS traits in the regions such as 2p14, 3q26, 7q21 and 15q21.

CONCLUSIONS

Our findings laid a foundation for further replication and fine-mapping studies as well as for positional and functional candidate gene studies, aiming at eventually finding the causal genetic variants and hidden mechanisms concerning FNCS geometry variation and the associated hip fractures.

What is the role of DXA, QUS and bone markers in fracture prediction, treatment allocation and monitoring?

There is evidence that treatment can decrease the risk of fractures in osteoporotic patients, and screening of these patients is therefore relevant. Diagnosis of osteoporosis is based on the T-score calculated from bone mineral density (BMD) measurements. BMD measurements have been widely used for the management of osteoporosis, and a low BMD is a strong risk factor for fractures. But BMD measurement has several limitations in both diagnosis, prediction of fracture risk, and treatment follow-up. Quantitative ultrasound (QUS) parameters, an alternative to BMD in the assessment of bone, are independent risk factors for osteoporotic fracture. However, the use of QUS cannot be recommended for both allocation and monitoring of treatment. Biochemical markers of bone remodelling can be useful for both prediction of fracture risk and monitoring of treatment if sources of variability are controlled.

Hyperechoic plaque: an ultrasound marker for osteoporosis in acute stroke patients with carotid disease

BACKGROUND

Osteoporosis is a significant complication of stroke, and hip fracture after a stroke is a frequent problem. Moreover, growing evidence links vascular and bone diseases, in the form of osteoporosis associated with both atherosclerosis and vascular calcification. The aim of our study is to detect bone change in the acute phase of ischemic stroke in patients with carotid disease and to verify the correlation with carotid echogenic plaques.

PATIENTS AND METHOD

Out of 245 subjects consecutively admitted to our Stroke Unit for their first ischemic stroke, we selected 49 patients with a first-ever stroke due to carotid atherosclerosis without a previous diagnosis of bone disease. We assessed risk factors for cerebrovascular disease as well as for osteoporosis, the degree of neurological deficit and disability, and bone mineral density that was quantified by bilateral hip dual energy X-ray absorbimetry. Osteoporosis was defined as a T score below -2.5. Carotid ultrasound was used to classify plaques in non-hyperechoic (grade 1) and hyperechoic plaque (grade 2).

RESULTS

We found a high prevalence of low bone mass density (BMD) in our patients (18 out of 49=36.7%), without relationship to the side of paresis. According to univariate analysis evidence of osteoporosis was correlated with age (p=0.05), score of Scandinavian Stroke Scale (p=0.01) and grade 2 plaque (p=0.01). According to multivariate analysis, there was a significant positive correlation between grade 2 plaques and osteoporosis (OR=6.58; 95% CI=1.57-27.54; p=0.01), which was stronger in women (OR=18.15; 95% CI=1.80-182.83; p=0.01). The percentage of intraplaque hyperechogenicity was inversely correlated with BMD (r=-0.411, p=0.016).

CONCLUSION

Osteoporosis is highly prevalent in acute atherosclerotic stroke patients. Carotid hyperechoic plaque is an independent marker of osteoporosis.

Pretreatment levels of bone turnover and the antifracture efficacy of alendronate: the fracture intervention trial

The influence of pretreatment bone turnover on alendronate efficacy is not known. In the FIT, we examined the effect of pretreatment bone turnover on the antifracture efficacy of daily alendronate given to postmenopausal women. The nonspine fracture efficacy of alendronate was significantly greater among both osteoporotic and nonosteoporotic women with higher baseline levels of the bone formation marker PINP.

INTRODUCTION

Previous trials have shown that high bone turnover is associated with greater increases in BMD among bisphosphonate-treated women. The influence of pretreatment bone turnover levels on antifracture efficacy has not been well studied.

MATERIALS AND METHODS

We randomized women 55-80 years of age with femoral neck BMD T scores < or = -1.6 to alendronate (ALN), 5-10 mg/day (n = 3105), or placebo (PBO; n = 3081). At baseline, 3495 women were osteoporotic (femoral neck BMD T score < or = -2.5 or prevalent vertebral fracture), and 2689 were not osteoporotic (BMD T score > -2.5 and no prevalent vertebral fracture). Pretreatment levels of bone-specific alkaline phosphatase (BSALP), N-terminal propeptide of type 1 collagen (PINP), and C-terminal cross-linked telopeptide of type 1 collagen (sCTx) were measured in all participants using archived serum (20% fasting). The risk of incident spine and nonspine fracture was compared in ALN- and PBO-treated subjects stratified into tertiles of baseline bone marker level.

RESULTS AND CONCLUSIONS

During a mean follow-up of 3.2 years, 492 nonspine and 294 morphometric vertebral fractures were documented. Compared with placebo, the reduction in nonspine fractures with ALN treatment differed significantly among those with low, intermediate, and high pretreatment levels of PINP levels (p = 0.03 for trend). For example, among osteoporotic women in the lowest tertile of pretreatment PINP (<41.6 ng/ml), the ALN versus PBO relative hazard for nonspine fracture was 0.88 (95% CI: 0.65, 1.21) compared with a relative hazard of 0.54 (95% CI: 0.39, 0.74) among those in the highest tertile of PINP (>56.8 ng/ml). Results were similar among women without osteoporosis at baseline. Although they did not reach statistical significance, similar trends were observed with baseline levels of BSALP. Conversely, spine fracture treatment efficacy among osteoporotic women did not differ significantly according to pretreatment marker levels. Spine fracture treatment efficacy among nonosteoporotic women was related to baseline BSALP (p = 0.05 for trend). In summary, alendronate nonspine fracture efficacy is greater among both osteoporotic and nonosteoporotic women with high pretreatment PINP. If confirmed in other studies, these findings suggest that bisphosphonate treatment may be most effective in women with elevated bone turnover.

Cost-effectiveness Strategies to Treat Osteoporosis in Elderly Women

BACKGROUND

Comparing the cost-effectiveness of various antiosteoporotic drugs has not been defined.

METHODS

We determined the cost-effectiveness of calcitonin, raloxifene, bisphosphates and PTH in a base-case cohort of women aged 65 or older with osteoporosis. After bone densitometry, women were stratified into groups of treatment or no treatment. Our outcome goal was a value of dollars 100,000 or less per quality-adjusted life years (QALY). A sensitivity analysis varied nonvertebral fracture reduction and compliance between the two most effective strategies to test various cost per QALY thresholds.

RESULTS

Bisphosphonates displayed the most favorable incremental cost saving and prevented more fractures in our base-case analysis. In a sensitivity analysis, virtually all values of bisphosphonates were under dollars 100,000 per QALY and parathyroid hormone (PTH) was between dollars 100,000 and dollars 200,000 per QALY.

CONCLUSIONS

Only bisphosphonates are cost-effective for fracture prevention in osteoporotic women aged 65 or older and this economic advantage is also maintained in subsets who have a lower relative risk of future fracture.

Application of the 1994 WHO classification to populations other than postmenopausal Caucasian women: the 2005 ISCD Official Positions

In 2003, the International Society for Clinical Densitometry (ISCD) developed Official Positions regarding the applicability of the World Health Organization (WHO) classification of bone mineral density to populations other than postmenopausal women. However, these prior Official Positions do not fully address bone mineral density reporting in females prior to menopause, men, and non-whites. During the 2005 ISCD Position Development Conference, members of the ISCD Expert Panel in conjunction with the ISCD Scientific Advisory Committee re-addressed these topics and, based upon stringent reviews of best available data, developed ISCD Official Positions that provide greater specificity and clarification with respect to the following: (1) the utility of the term 'osteopenia'; (2) utilization of T- and Z-scores for bone mineral density reporting; (3) when to apply the WHO densitometric classification; and (4) which normative database(s) should be used for non-white individuals. Briefly, the term "osteopenia" is retained, but 'low bone mass' or 'low bone density' is preferred. Z-scores, not T-scores, are preferred in females prior to menopause and males under age 50. In these individuals, a Z-score of -2.0 or lower is defined as "below the expected range for age" and a Z-score above -2.0 is "within the expected range for age." T-scores are preferred and the WHO classification is applicable for postmenopausal women and men age 50 and older. These Official Positions, rationale and evidence are discussed in the following report.

The interaction of ethnicity and chronic disease as risk factors for osteoporotic fractures: a comparison in Canadian Aboriginals and non-Aboriginals

INTRODUCTION

Efforts to develop global methods for absolute fracture risk prediction are currently limited by uncertainty over the validity of these models in non-White populations. Aboriginal Canadians have higher fractures rates than non-Aboriginals. This analysis examined the interaction of ethnicity with diabetes mellitus, disease comorbidity and substance abuse as possible explanatory variables.

METHODS

A retrospective, population-based matched cohort study of fracture rates was performed using Manitoba administrative health data (1984-2003). The study cohort consisted of 27,952 registered Aboriginal adults (aged 20 years or older) and 83,856 non-Aboriginal controls (matched three to one for year of birth and gender). Diabetes mellitus, number of ambulatory disease groups (ADGs), substance abuse and incident fractures were based upon validated definitions. Poisson regression analyses of fracture rates modelled the explanatory variables as main effects and two-way interactions with ethnicity.

RESULTS

Osteoporotic fracture rates were approximately twofold higher in the Aboriginal cohort (p<0.0001). Diabetes, greater number of ADGs and substance abuse were all more common in the Aboriginal cohort (all p<0.0001). These factors were associated with increased fracture rates (all p<0.0001) and significantly higher population attributable risk percent in the Aboriginal cohort (all p<0.0001). However, no significant interactions between the risk factors and ethnicity were observed (p>0.1 for all interaction effects).

CONCLUSION

Greater prevalence of diabetes, comorbidity and substance abuse contributes to higher rates of fracture. The relative risk of fracture for these factors is similar for both Aboriginal and non-Aboriginals despite large differences in absolute fracture risk and risk factor prevalence.

Long-term recreational gymnastics provides a clear benefit in age-related functional decline and bone loss. A prospective 6-year study

INTRODUCTION

Bone fragility and decreased functional performance are risk factors for osteoporotic fractures. The influence of long-term recreational gymnastics on the maintenance of bone rigidity and physical performance was evaluated.

METHODS

One hundred and seven gymnasts and 110 referents (93% of the original sample) participated in this 6-year prospective study. Analysis of covariance (ANCOVA) was used to estimate the between-group differences and changes by time, and regression analyses to find predictors for changes.

RESULTS

In both groups agility and leg extensor power decreased by over 3% and 10%, respectively, but the original between-group differences, favoring the gymnasts, persisted. Proximal femur bone mineral content (BMC) decreased approximately 0.5% per year in both groups, and femoral neck section modulus decreased. Trabecular density of the distal tibia declined only marginally, and cortical area of the tibial midshaft remained unchanged, while cortical density decreased about 2% in both groups. After adjustment by age, height, weight, change in weight, and follow-up time, antiresorptive medication and high calcium intake accounted most for the maintenance of bone rigidity.

CONCLUSIONS

In spite of similar rates of decline in bone characteristics and physical performance, the recreational gymnasts' overall physical condition was comparable to the level that their less active referents had shown approximately 5 years earlier.

The fracture risk index and bone mineral density as predictors of vertebral structural failure

Structural failure becomes increasingly likely as the load on bone approximates or exceeds the bone's ability to withstand it. The vertebral fracture risk index (FRI) expresses the risk for structural failure as a ratio of compressive stress (load per unit area) to estimated failure stress, and so should be a more sensitive and specific predictor of vertebral fracture than spine areal BMD (aBMD) or volumetric BMD (vBMD), surrogates of bone strength alone. To address this issue, we analyzed the results of a case-control study of 89 postmenopausal women with vertebral fractures and 306 controls in Melbourne, Australia, and a 10-year community-based prospective study in which 30 postmenopausal women who had incident vertebral fractures were compared with 150 controls in Lyon, France. The FRI and vBMD of the third lumbar vertebral body and spine aBMD were derived using dual X-ray absorptiometry. In the cross-sectional analysis, each SD increase in FRI was associated with 2.1-fold (95% confidence interval [CI], 1.55-2.73) increased vertebral fracture risk, while each SD decrease in aBMD or vBMD was associated with 4.0-fold (95% CI, 2.69-6.18 and 2.65-6.94, respectively) increase in risk. Using receiver operating characteristic (ROC) analysis, the FRI was less sensitive and specific than aBMD in discriminating cases and controls (area under ROC, 0.76 vs 0.84, p<0.01). The area under ROC curve did not differ between FRI and vBMD (0.76 vs 0.79, NS). In the prospective data set, the FRI was not predictive [hazard ratio, HR, 1.20 (95% CI, 0.9-1.7)] and was in contrast to aBMD [HR, 2.4 (95% CI, 1.5-3.8)] and vBMD [HR, 2.1 (95% CI, 1.39-3.17)]. There was also lower sensitivity using a cutoff value of FRI>or=1 compared with aBMD T-score of -2.5 SD in both studies. There was poor agreement (kappa=0.13-0.18) between FRI and aBMD T -scores in detecting fractures; each method only identified around 50% of fractured cases. Within the constraints of the sample size, we concluded that applying a biomechanical index such as FRI at the spine is no better in discriminating fracture cases and controls than conventional aBMD or vBMD. The FRI may not predict incident vertebral fractures.

Predicting the risk of fracture at any site in the skeleton: are all bone mineral density measurement sites equally effective?

The ability to assess a patient's risk of fracture is fundamental to the clinical role of bone densitometry. Fracture discrimination is quantified by the relative risk (RR), defined as the increased risk of fracture for a 1 standard deviation decrease in bone mineral density (BMD). The larger the value of RR, the more effective measurements are at identifying patients at risk of fracture. Epidemiological studies show that RR values for predicting the risk of any fracture are approximately the same for all BMD measurement sites. In this study, we show theoretically that this interesting observation is predictable and a consequence of two related observations: (1) that fracture prediction by BMD measurement sites distant from the fracture site is quantitatively explained by the correlation of BMD measurements and (2) that all correlation coefficients between distant BMD sites are comparable, with values in the range r = 0.55-0.65. The first of these conditions (referred to as the correlation hypothesis) is important because it sets a lower limit on the RR values at distant BMD sites on the assumption that measurements at these sites contain no independent information about fracture risk over and above that provided by their correlation with the fracture site BMD. If the correlation hypothesis is true, the present study points to the importance of the correlation coefficient between BMD sites as a key index that is indicative of the ability of different types of measurement to predict fracture risk. If, on the contrary, the correlation hypothesis is not valid, there is scope to improve bone densitometry by further studies to better identify those measurements that do provide independent information about fracture risk and how best to integrate this information with existing techniques to improve decision making.

Cross-calibration and minimum precision standards for dual-energy X-ray absorptiometry: the 2005 ISCD Official Positions

The International Society for Clinical Densitometry (ISCD) Committee on Standards of Bone Measurement (CSBM) consists of experts in technical aspects of bone densitometry. The CSBM recently reviewed the scientific literature on cross-calibration and precision assessment. A report with recommendations was presented at the 2005 ISCD Position Development Conference (PDC). Based on a thorough review of the data by the ISCD Expert Panel during the conference, the ISCD adopted Official Positions with respect to (1) cross-calibration when changing or replacing hardware; (2) the approach to cross-calibration when an entire system is changed to one made by either the same or a different manufacturer; (3) when no cross-calibration study or bone mineral density (BMD) comparison is done between facilities; and (4) the minimum acceptable precision for an individual technologist. We present here the ISCD Official Positions on these topics that were established as a result of the 2005 PDC, together with the associated rationales and supportive evidence.

Association analysis of estrogen receptor alpha gene polymorphisms with cross-sectional geometry of the femoral neck in Caucasian nuclear families

Bone geometry is a key factor in bone strength, which is the ultimate intrinsic determinant of fracture risk. Though the heritability of bone geometry is high, little effort has been spent on searching for the underlying genes. In this study, employing a sample of 1,873 subjects from 405 Caucasian nuclear families, we studied seven single nucleotide polymorphisms (SNPs) and their haplotypes of the ER-alpha gene for association with six hip geometric variables, namely, cross-sectional area (CSA), cortical thickness (CT), endocortical diameter (ED), subperiosteal width (W), sectional modulus (Z) and buckling ratio (BR). The major method used was the quantitative transmission disequilibrium test (QTDT). Our major findings were summarized below. The within-family association between SNP4 (rs1801132) in exon 4 with endocortical diameter and subperiosteal width was detected in single locus analyses (P=0.008 and 0.021, respectively) and verified in haplotype analyses (P=0.034 and 0.058, respectively). The total association of SNP4 with these two diameters was also observed in both single locus and haplotype analyses (P=0.005 and 0.031 for ED, plus P=0.003 and 0.070 for W). In addition, the total association between SNP5 (rs932477) in intron 4 with cortical thickness and buckling ratio was detected (single locus analyses: P=0.035 and 0.041, respectively). Haplotype analyses further supported the above association (P=0.010 and 0.004, respectively). Similar patterns of associations with the studied SNPs and their haplotypes were present in subsamples stratified by sex, too. However, after permutation tests, the empirical significance level was set as P<0.011, which renders most associations insignificant. Therefore, we concluded that polymorphisms in the ER-alpha gene were nominally associated with femoral neck (FN) geometry variables estimated from DXA. Such genetic effects on hip geometry were not sex specific.

A list of device-specific thresholds for the clinical interpretation of peripheral x-ray absorptiometry examinations

The UK National Osteoporosis Society (NOS) has recently issued new guidelines on the use of peripheral x-ray absorptiometry (pDXA) devices in managing osteoporosis. The NOS guidelines recommend a triage approach in which patients' bone mineral density (BMD) measurements are interpreted using upper and lower thresholds specific to each type of pDXA device. The thresholds are defined so that patients with osteoporosis at the hip or spine are identified with 90% sensitivity and 90% specificity. Patients with a pDXA result below the lower threshold are likely to have osteoporosis at the hip or spine, patients with a result above the upper threshold are unlikely to have osteoporosis, while those between the two thresholds require a hip and spine BMD examination for a definitive diagnosis. This report presents data from a multicenter study to establish the triage thresholds for a range of pDXA devices in use in the UK. The subjects were white female patients aged 55-70 years who met the normal referral criteria for a BMD examination. For each device, at least 70 women with osteoporosis at the hip or spine and 70 women without osteoporosis were enrolled. All women had hip and spine BMD measurements using axial DXA systems that were interpreted using the National Health and Nutrition Examination Survey (NHANES) reference range for the hip and the manufacturers' reference ranges for the spine. Data are presented for five different devices: the Osteometer DTX-200 (forearm BMD), the Schick AccuDEXA (hand BMD), the GE Lunar PIXI (heel BMD), the Alara MetriScan (hand BMD), and the Demetech Calscan (heel BMD). The clinical measurements were supplemented by theoretical modeling to estimate the age dependence of the triage thresholds and the effect of the correlation coefficient between pDXA and axial BMD on the percentage of women referred for an axial BMD examination. In summary, this study provides thresholds for implementing the new NOS guidelines for managing osteoporosis using pDXA devices. The figures reported apply to postmenopausal white women aged 55-70 years who meet the conventional criteria for a BMD examination. The results confirm that the thresholds are specific to each type of pDXA device and that the NOS triage algorithm requires 40% of women to have an axial DXA examination.

Fracture Reduction Affects Medicare Economics (FRAME): impact of increased osteoporosis diagnosis and treatment

Osteoporosis is a common, debilitating disease affecting US Medicare beneficiaries, yet diagnosis and treatment lag behind medical advances. We estimated the cost of fractures to the Medicare program and the impact of increasing osteoporosis diagnosis and treatment. A Markov model was used to predict fracture incidence and costs in postmenopausal women aged 65 years and older, over 3 years (2001-2003). Only 1.80 million women were estimated to receive a Medicare-reimbursed bone mineral density (BMD) test in 2001. We evaluated the budget impact of testing an additional 1 million women from Medicare and patient perspectives. These women were stratified into high-risk (osteoporotic with prevalent vertebral fracture) and moderate-risk (without prevalent vertebral fracture) groups. During 2001-2003, an estimated 2.39 million fractures occurred among the 5.11 million women aged 65+ with osteoporosis, at a cost to Medicare of 12.96 billion dollars. We projected that BMD testing of an additional 1 million women in 2001 would result in treatment of 440,000 new patients with a bone-specific medication, preventing over 35,000 fractures over the 3 years. The decrease in fractures would produce a net discounted savings to the Medicare budget of 77.86 million dollars. Medicare's hospital inpatient cost would decrease by 115.41 million dollars and long-term care cost by 43.51 million dollars, more than offsetting incremental outpatient cost of 81.07 million dollars. Patients would benefit from fracture avoidance, but their out-of-pocket medical costs would increase by 63.49 million dollars during 2001-2003, or 1,771 dollars per fracture avoided. Sensitivity analyses showed that savings to the Medicare program varied in proportion to the unit cost of fractures, fracture risk of the populations tested, treatment rate, and adherence to therapy. Increased osteoporosis diagnosis may produce savings for the Medicare program if interventions are targeted to women at elevated risk for fracture and may be budget neutral if all older women are screened.

The discriminative ability of peripheral and axial bone measurements to identify proximal femoral, vertebral, distal forearm and proximal humeral fractures: a case control study

Previous studies evaluating peripheral bone measurement devices have often used discontinued technologies, compared single devices, only evaluated a single fracture syndrome or failed to make a comparison with central densitometry, which is currently the gold standard for fracture discrimination. We have used a case control study to evaluate the ability of different peripheral and central bone techniques to discriminate between fracture cases and controls, determine the impact of different measurement sites, evaluate the role of measuring the cortical or trabecular envelopes using quantitative computed tomography (QCT) and determine the impact of using combinations of sites and techniques on fracture discrimination. We recruited postmenopausal women with proximal femoral (n=53), vertebral (n=73), distal forearm (n=78) or proximal humeral (n=75) fractures, and 500 population-based women (age 55-80 years). All subjects had measurements of the spine, total hip and distal forearm with dual-energy X-ray absorptiometry (DXA), distal forearm QCT and quantitative ultrasound (QUS) of the heel (four devices), finger (two devices), radius and metatarsal. The association of each device with fracture was expressed as the age-adjusted standardized odds ratios (sOR) per 1-SD decrease of population variance. The association of bone measurements with fracture was site-specific. We found the hip (sOR up to 3.40) and vertebral (sOR up to 4.67) fractures were more closely associated with central bone measurements than upper limb fractures (sOR 1.96 and 2.05). The performance of heel broadband ultrasound attenuation (sOR 2.09-2.41), heel speed of sound (sOR 1.79-2.28) and peripheral BMD (sOR 2.07 and 2.24) was comparable with total hip (sOR 2.46) and lumbar spine DXA (sOR 2.31) in discriminating all types of osteoporotic fracture. In general, measuring cortical or trabecular envelopes did not increase sOR. However, combining different measurement sites or technologies provided additional information, which was independent of total hip BMD. The ability of different bone measurements to discriminate between fracture cases and controls is device- and site-specific, with additional information obtained by combining measurement sites and technologies.

Subclinical hypervitaminosis A in rat: measurements of bone mineral density (BMD) do not reveal adverse skeletal changes

We have previously shown that subclinical hypervitaminosis A in rats causes fragile bones. To begin to investigate possible mechanisms for Vitamin A action we extended our previous study. Forty-five mature female Sprague-Dawley rats were divided into three groups, each with 15 animals. They were fed a standard diet containing 12IU Vitamin A per g pellet (control, C), or a standard diet supplemented with 120 IU ("10xC") or 600 IU ("50xC") Vitamin A/g pellet for 12 weeks. At the end of the study, serum retinyl esters were elevated 4- and 20-fold. Although neither average food intake nor final body weights were significantly different between groups, a dose-dependent reduction in serum levels of Vitamin D and E, but not Vitamin K, was found. In the 50xC-group the length of the humerus was the same as in controls, but the diameter was reduced (-4.1%, p<0.05). Peripheral quantitative computed tomography (pQCT) at the diaphysis showed that bone mineral density (BMD) was unchanged and that periosteal circumference had decreased significantly (-3.7%, p<0.05). Ash weight of the humerus was not affected, but since bone volume decreased, volumetric BMD, as measured by the bone ash method, even increased (+2.5%, p<0.05). In conclusion, interference with other fat-soluble Vitamins is a possible indirect mechanism of Vitamin A action. Moreover, BMD measurements do not reveal early adverse skeletal changes induced by moderate excesses of Vitamin A in rats. Since the WHO criterium for osteoporosis is based on BMD, further studies are warranted to examine whether this is also true in humans.

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

BMD is a major determinant of the risk of fragility fractures, but the role of the rate of postmenopausal bone loss is still unclear. In 671 postmenopausal women from the OFELY cohort, we found that the rate of bone loss was significantly associated with fracture risk independently of other well-known predictors including BMD and previous fractures.

INTRODUCTION

The level of BMD is a major determinant of the risk of fragility fractures, but the role of the rate of postmenopausal bone loss is still unclear.

MATERIALS AND METHODS

In the OFELY study, we analyzed the risk of fracture in 671 postmenopausal women (mean age, 62.2 +/- 9 years), according to the rate of bone loss. BMD was measured annually by DXA at the forearm, with a mean number of measurements of 10.3 +/- 2.6. Peripheral fractures, all confirmed by radiographs, were prospectively registered, and vertebral fractures were evaluated with spine radiographs every 4 years.

RESULTS

During a median (interquartile range [IQ]) of 11.2 years (11-12.3 years) of follow-up, 183 incident fragility fractures including 53 vertebral and 130 nonvertebral fractures were recorded in 134 women. The annual median +/- IQ rate of bone loss, calculated from the slope, was -0.30 +/- 0.76% at the mid-radius, -0.55 +/- 0.79% at the distal radius, and -0.40 +/- 0.96% at the ultradistal radius. Women with incident fracture had a rate of bone loss (before fracture) higher by 38-53% than those without fracture (p = 0.0003-0.016). Using multivariate Cox regression models, we found that bone loss in the highest tertile at the mid-radius, distal radius, and ultradistal radius was associated with a significant increased risk of all fractures with an hazard ratio from 1.45 to 1.70 (p = 0.02 to p = 0.009 after adjusting for age, previous fractures, maternal history of fracture, physical activity, grip strength, falls, and baseline BMD).

CONCLUSIONS

The rate of bone loss in postmenopausal women is significantly associated with fracture risk independently of other well-known predictors such as BMD and history of fractures.

High prevalence of vertebral deformity in premenopausal systemic lupus erythematosus patients

In this paper we searched for vertebral deformities in a group of 70 premenopausal systemic lupus erythematosus (SLE) patients (31.8 +/- 8.1 years old) and compared them to a matched control group of 22 healthy women (32.0 +/- 8.9 years old). Patients and controls performed spine X-ray (XR) morphometry and lumbar spine and femoral neck bone mineral density (BMD). Clinical data was obtained by a questionnaire and charts review. Thoracic or lumbar spine fracture was observed in 15 (21.4%) SLE patients, while no deformities were found in the control group (P = 0.018). BMD was not different amongst SLE patients and controls and between SLE patients with or without deformities. Although BMD could not predict what patient have deformity, seven patients (46.6%) with deformity had a lumbar spine or femoral neck Z-score less than - 1 SD [median = -0.59 (-3.72 to +0.88) and -0.20 (-4.05 to + 1.87)] respectively. In addition, we found a negative correlation between number of fracture per patient and lumbar spine and femoral neck BMD (R = 0.58, P = 0.04 and R = 0.84, P = <0.0001 respectively). No significant correlation was found between number of deformities and clinical data. This is the first study to search for vertebral deformities in SLE patients and to demonstrate a high prevalence of deformities in a relative young SLE population. These findings bring up the necessity to look for spine deformities in this group of women regardless the BMD.

Diet and exercise during growth have site-specific skeletal effects: a co-twin control study

Exercise and improved nutrition offer safe, low-cost and widely applicable approaches to potentially reduce the burden of fractures. We conducted a cross-sectional study of 30 monozygotic and 26 dizygotic male twin pairs, aged 7-20 years to test the following hypotheses: (1) Associations between bone mass and dimensions and exercise are greater than between bone mass and dimensions and protein or calcium intakes; (2) exercise or nutrient intake are associated with appendicular bone mass before puberty and axial bone mass during and after puberty. Total body and posteroanterior (PA) lumbar spine bone mineral content (BMC) and mid-femoral shaft dimensions were measured using dual energy X-ray absorptometry (DEXA). Relationships between within-pair differences in nutrient intake (determined by weighed-food diaries) or exercise duration (determined by questionnaire) and within-pair differences in BMC and bone dimensions were tested using linear regression analysis. In multivariate analyses, within-pair differences in exercise duration were associated with within-pair differences in total body, leg and spine BMC, and cortical thickness. Every-hour-per-week difference in exercise was associated with a 31-g (1.2%) difference in total body BMC, a 10-g (1.4%) difference in leg BMC, a 0.5-g difference in spine BMC and a 0.1-mm difference in cortical thickness ( p <0.01- p <0.1). A 1-g difference in protein intake was associated with a 0.8-g (0.4%) difference in arm BMC ( p <0.05). These relationships were present in peri-pubertal and post-pubertal pairs but not in pre-pubertal pairs. Exercise during growth appears to have greater skeletal benefits than variations in protein or calcium intakes, with the site-specific effects evident in more mature twins.

Elevated serum fluoride concentrations in women are not related to fractures and bone mineral density

Epidemiologic studies of the relations between drinking-water fluoride levels and bone mineral density (BMD) and fracture are characterized by disparate conclusions and an absence of information about individual circulating fluoride levels. This study relates serum fluoride concentrations, which reflect individual fluoride exposures, to BMD and bone fractures. Data are from 1300 female residents of 3 small communities in which the water fluoride concentrations were 52.6 or 210.4 micromol/L. Circulating serum fluoride concentrations were assessed by ion-specific electrode. Fluoride intake was estimated from interviews describing water and water-based beverage consumption and duration of residence in the community. BMD was measured by dual-energy X-ray densitometry and single-photon densitometry. Self-reported fractures were confirmed by medical record abstraction. The mean serum fluoride concentration in the high-fluoride community, 2.11 +/- 0.05 micromol/L, was significantly higher than serum fluoride concentrations in the control and high-calcium communities with water fluoridation to 52.6 micromol/L. The mean serum fluoride concentrations in these latter 2 communities were 1.6 +/- 0.04 and 1.22 +/- 0.05 micromol/L, respectively. Serum fluoride was not significantly related to BMD after adjusting for covariates including age and body size. The mean distal radius BMD, however, was significantly higher in the high-fluoride community. Serum fluoride concentrations were not related to incident osteoporotic fractures with 4 y of observation. Serum fluoride concentrations were not associated with BMD or osteoporotic fractures among female residents of communities with water fluoride concentrations of 52.6 or 210.4 micromol/L.

Genetic polymorphisms of OPG, RANK, and ESR1 and bone mineral density in Korean postmenopausal women

To evaluate the effects of genetic polymorphisms of OPG, RANK, and ESR1, which regulate osteoclastogenesis, on bone mineral density (BMD), a cross-sectional study was conducted in 650 Korean postmenopausal women. BMDs of the distal radius and the calcaneus were measured by dual energy X-ray absorptiometry (DXA). Genetic polymorphisms of OPG 163 A > G, 1181 G > C; RANK 421 C > T, 575 T > C; and ESR1 1335 C > T, 2142 G > A were determined by matrix-assisted laser desorption/ionization-time of flight (MALDI-ToF) mass spectrometry. The differences between the BMDs of the genotypes of OPG, RANK, and ESR1 were analyzed by multiple linear regression model adjusted for age and body mass index. Women with the OPG 1181 CC genotype had higher BMDs at the distal radius (7%) and calcaneus (10%) than those with the GG genotype; and these differences were statistically significant (P = 0.001 and P = 0.007, respectively). A significant association was also observed between RANK 575 T > C and calcaneus BMD (P for trend = 0.017). No significant association was observed between BMDs and the polymorphisms of ESR1. The association between OPG 1181 G > C and BMD was profound in subjects with the RANK 575 TT or ESR1 2142 GG genotypes; women with OPG 1181 CC had higher BMDs at the distal radius (11%) and calcaneus (11%) than those with OPG 1181 GG only in women with RANK 575 TT genotype (P = 0.002 and P = 0.021, respectively). These results suggest that OPG genetic polymorphisms, especially with the RANK 575 TT or ESR1 2142 GG genotypes, are related to low BMD in postmenopausal Korean women.

Trabecular rod buckling index in thoraco-lumbar vertebral bone†

The need for improved mechanistic understanding of cancellous bone failure is at the core of important clinical problems such as osteoporosis, as well as basic biological issues such as bone formation and adaptation. Three-dimensional (3D) anaglyphs were produced from 15 T12 and L1 vertebral bodies, which encompass the adult life span in both sexes. The anaglyphs were viewed with red-green stereo glasses, using an image analyzer, and trabecular thickness and trabecular length were measured. From biomechanical principles, the strength of individual trabeculae can be estimated from measurement of trabecular rod thickness and trabecular rod length as the load to buckling index. The distribution of the load to buckling index was best described by a log normal curve. Trabecular rod thickness, trabecular rod length, and load to buckling index for males were consistently greater than for females. With aging, trabecular rod thickness, and the load to buckling index decrease for males while trabecular rod length increases for females. In this study, the load to buckling index for thoraco-lumbar vertebral trabecular rods potentially quantifies a greater risk of vertebral fracture for females. Decreased trabecular rod thickness or increased trabecular rod length result in the strength of trabeculae shifting closer to a putative fracture threshold. The corollary being that there is a reduced safety margin for resistance to mechanical loads for the vertebral bodies. The 3D anaglyph technique for measuring trabecular dimensions provides an accurate and precise methodology by which these morphological studies can be undertaken.

Bone and Mineral Metabolism

Although bones are normally thought of as supporting structures that fracture when one falls, bone is actually a very active metabolic organ. It is vital in the regulation of calcium and phosphate metabolism, magnesium storage, and in buffering metabolic acido-sis. Bone and mineral metabolism and some of their disorders are presented in this article.

Infrared analysis of bone in health and disease

Infrared spectroscopy, microspectroscopy, and microspectroscopic imaging have been used to probe the composition and physicochemical status of mineral and matrix of bone in normal and diseased tissues using a series of validated parameters that reflect quantitative and qualitative properties. In this review, emphasis is placed on changes in bone's composition and physiochemical status during osteoporosis and the impact of currently used therapeutics on these parameters, although the impact of infrared microscopy in other pathological states is briefly discussed.

Fracture prediction by bone density measurements at sites other than the fracture site: the contribution of BMD correlation

It is widely believed that the most reliable BMD measurement for predicting fracture risk at any given skeletal site is one made at the fracture site itself. This study examines the hypothesis that the ability of BMD measurements at other distant sites in the skeleton remote from the fracture site to predict fracture risk is due to their correlation with the BMD measurements at the fracture site. We refer to this assumption as the correlation hypothesis. We show that the correlation hypothesis predicts the relationship betadist = rbetafrac, where beta is the gradient of the exponential relationship between fracture risk and Z-score, betafrac is the beta-value for the fracture site, betadist the beta-value for the distant BMD site, and r is the correlation coefficient between the Z-scores at the two sites. In practice it is important to consider the effect of BMD measurement errors on the (r, beta) relationship. We show that the effect of errors at the distant site is to reduce betadist and r in a way that preserves their original relationship. When errors at the fracture site are taken into account the effect on the (r, beta) plot is for the point representing the fracture site to fall below the extrapolation of the straight-line relationship predicted for the points representing the distant BMD sites. We tested the correlation hypothesis by using data from the Study of Osteoporotic Fractures to examine the (r, beta) plots for hip, spine and forearm fractures. For the hip the data are consistent with a straight-line relationship and suggest that measurements made at other sites provide no additional information about fracture risk over and above that provided by hip BMD itself. For spine and forearm fractures the data show that distant sites do provide additional information about fracture risk in a way that is quantitatively consistent with the BMD measurement errors reported in cadaver studies. It is clear that random BMD errors at the fracture site cause loss of information about fracture risk and that some of this lost information is recoverable from measurements made at other sites in the skeleton. Overall, this study points to BMD correlation as an important factor in explaining the ability of measurements made at distant sites to predict fracture risk.

Simple Computer Model for Calculating and Reporting 5-Year Osteoporotic Fracture Risk in Postmenopausal Women

PURPOSE

To devise, validate, and test a software model that improves how clinicians calculate individual risk for osteoporotic fracture and expected treatment benefit.

METHODS

We developed a simple model of seven easily ascertained items plus bone mineral density (BMD) that calculates absolute fracture risk and expected absolute risk reduction after treatment. Baseline clinical variables and longitudinal fracture data from two large osteoporosis cohort studies validated the model's accuracy in predicting fracture risk. We then surveyed 298 clinicians to evaluate the likelihood they would prescribe alendronate in three hypothetical cases, first given the clinical data alone and then with model-derived data on fracture risk and expected treatment benefit.

RESULTS

We found a strong linear relationship with the model's predicted fracture risk and observed fracture rates in two large observational cohorts but the model overestimated risk 2-3 fold. The model predicted a 1:200 5-year risk for spinal fracture and a 1:40 risk for nonspinal fracture in an index case of a younger, thin, osteopenic woman. Given this hypothetical history with BMD t-scores, 26% of clinicians were likely to prescribe alendronate; when also given model-calculated 5-year fracture risks with or without treatment, only 13% were likely to prescribe alendronate (p < 0.001). For 2 other osteoporosis patients in whom risk was much higher, further information on fracture risk and expected treatment benefit did not alter prescribing.

CONCLUSIONS

Reporting absolute fracture risk with and without treatment promises to be most useful in women with osteopenia, a common clinical dilemma in younger postmenopausal women.

Longitudinal progression of fracture prevalence through a population of postmenopausal women with osteoporosis

AIM

To determine the longitudinal progression of fractures through a population of osteoporotic women with no existing vertebral fractures.

METHODS

The probability of having one or more vertebral fractures in the next year given a current status of 0-13 existing vertebral fractures was estimated using data from control patients of an osteoporosis clinical trial program. Fracture probabilities were used to form a transition matrix that models the change in fracture state from one year to the next. A Markov model was used to show the distribution of fracture prevalence over time for a population of women with osteoporosis but, initially, with no existing vertebral fractures.

RESULTS

An osteoporotic woman without existing vertebral fractures has a 7.7% chance (95% CI, 5.8% to 9.9%) of having a vertebral fracture within 1 year. After 5 years, 33% (95% CI, 25% to 41%) will have developed vertebral fractures, of which 11% (95% CI, 8% to 16%) will have > or =2 fractures. After 10 years, 55% (95% CI, 44% to 65%) will have developed vertebral fractures, of which 29% (95% CI, 22% 37%) will have > or =2 fractures. Each 1% absolute reduction in the annual first-fracture risk corresponds to an approximate 4% reduction in the 5-year fracture incidence. Therefore, reducing the risk of first fracture from 8% to 2% reduces the 5-year fracture incidence from approximately 34% to approximately 10%.

CONCLUSIONS

Fracture prevalence rapidly increases over time in a population of osteoporotic women despite treatment with calcium and vitamin D supplements. Identifying and treating patients at risk of fracture, but who have not yet sustained a fracture, will substantially reduce the long-term burden of osteoporosis.

Demographic risk factors for fracture in First Nations people

BACKGROUND

Recently, First Nations people were shown to be at high fracture risk compared with the general population. However, factors contributing to this risk have not been examined. This analysis focusses on geographic area of residence, income level, and diabetes mellitus as possible explanatory variables since they have been implicated in the fracture rates observed in other populations.

METHODS

A retrospective, population-based matched cohort study of fracture rates was performed using the Manitoba administrative health data (1987-1999). The First Nations cohort included all Registered First Nations adults (20 years or older) as indicated in either federal and/or provincial files (n = 32,692). Controls (up to three for each First Nations subject) were matched by year of birth, sex and geographic area of residence. After exclusion of unmatched subjects, analysis was based upon 31,557 First Nations subjects and 79,720 controls.

RESULTS

Overall and site-specific fracture rates were significantly higher in the First Nations cohort. Income quintile, geographic area of residence, and diabetes were fracture determinants but the excess fracture risk of First Nations ethnicity persisted even after adjustment for these factors.

CONCLUSION

First Nations people are at high risk for fracture but the causal factors contributing to this are unclear. Further research is needed to evaluate the importance of other potential explanatory variables.