Ten-year absolute risk of osteoporotic fractures according to BMD T score at menopause: the Danish Osteoporosis Prevention Study

Hormone-Related and Drug-Induced Osteoporosis: A Cellular and Molecular Overview

Osteoporosis resulting from an imbalance of bone turnover between resorption and formation is a critical health issue worldwide. Estrogen deficiency following a nature aging process is the leading cause of hormone-related osteoporosis for postmenopausal women, while glucocorticoid-induced osteoporosis remains the most common in drug-induced osteoporosis. Other medications and medical conditions related to secondary osteoporosis include proton pump inhibitors, hypogonadism, selective serotonin receptor inhibitors, chemotherapies, and medroxyprogesterone acetate. This review is a summary of the cellular and molecular mechanisms of bone turnover, the pathophysiology of osteoporosis, and their treatment. Nuclear factor-κβ ligand (RANKL) appears to be the critical uncoupling factor that enhances osteoclastogenesis. In contrast, osteoprotegerin (OPG) is a RANKL antagonist secreted by osteoblast lineage cells. Estrogen promotes apoptosis of osteoclasts and inhibits osteoclastogenesis by stimulating the production of OPG and reducing osteoclast differentiation after suppression of IL-1 and TNF, and subsequent M-CSF, RANKL, and IL-6 release. It can also activate the Wnt signaling pathway to increase osteogenesis, and upregulate BMP signaling to promote mesenchymal stem cell differentiation from pre-osteoblasts to osteoblasts rather than adipocytes. Estrogen deficiency leads to the uncoupling of bone resorption and formation; therefore, resulting in greater bone loss. Excessive glucocorticoids increase PPAR-2 production, upregulate the expression of Dickkopf-1 (DKK1) in osteoblasts, and inhibit the Wnt signaling pathway, thus decreasing osteoblast differentiation. They promote osteoclast survival by enhancing RANKL expression and inhibiting OPG expression. Appropriate estrogen supplement and avoiding excessive glucocorticoid use are deemed the primary treatment for hormone-related and glucocorticoid-induced osteoporosis. Additionally, current pharmacological treatment includes bisphosphonates, teriparatide (PTH), and RANKL inhibitors (such as denosumab). However, many detailed cellular and molecular mechanisms underlying osteoporosis seem complicated and unexplored and warrant further investigation.

Osteoporosis Due to Hormone Imbalance: An Overview of the Effects of Estrogen Deficiency and Glucocorticoid Overuse on Bone Turnover

Osteoporosis is a serious health issue among aging postmenopausal women. The majority of postmenopausal women with osteoporosis have bone loss related to estrogen deficiency. The rapid bone loss results from an increase in bone turnover with an imbalance between bone resorption and bone formation. Osteoporosis can also result from excessive glucocorticoid usage, which induces bone demineralization with significant changes of spatial heterogeneities of bone at microscale, indicating potential risk of fracture. This review is a summary of current literature about the molecular mechanisms of actions, the risk factors, and treatment of estrogen deficiency related osteoporosis (EDOP) and glucocorticoid induced osteoporosis (GIOP). Estrogen binds with estrogen receptor to promote the expression of osteoprotegerin (OPG), and to suppress the action of nuclear factor-κβ ligand (RANKL), thus inhibiting osteoclast formation and bone resorptive activity. It can also activate Wnt/β-catenin signaling to increase osteogenesis, and upregulate BMP signaling to promote mesenchymal stem cell differentiation from pre-osteoblasts to osteoblasts, rather than adipocytes. The lack of estrogen will alter the expression of estrogen target genes, increasing the secretion of IL-1, IL-6, and tumor necrosis factor (TNF). On the other hand, excessive glucocorticoids interfere the canonical BMP pathway and inhibit Wnt protein production, causing mesenchymal progenitor cells to differentiate toward adipocytes rather than osteoblasts. It can also increase RANKL/OPG ratio to promote bone resorption by enhancing the maturation and activation of osteoclast. Moreover, excess glucocorticoids are associated with osteoblast and osteocyte apoptosis, resulting in declined bone formation. The main focuses of treatment for EDOP and GIOP are somewhat different. Avoiding excessive glucocorticoid use is mandatory in patients with GIOP. In contrast, appropriate estrogen supplement is deemed the primary treatment for females with EDOP of various causes. Other pharmacological treatments include bisphosphonate, teriparatide, and RANKL inhibitors. Nevertheless, more detailed actions of EDOP and GIOP along with the safety and effectiveness of medications for treating osteoporosis warrant further investigation.

[Menopause, menopause hormone therapy and osteoporosis. Postmenopausal women management: CNGOF and GEMVi clinical practice guidelines]

Postmenopausal osteoporosis is a frequent clinical condition, which affects nearly 1 in 3 women. Estrogen deficiency leads to rapid bone loss, which is maximal within the first years after the menopause transition and can be prevented by menopause hormone therapy (MHT). Assessment of the individual risk of osteoporosis is primarily based on the measurement of bone mineral density (BMD) at the spine and femur by DXA. Clinical risk factors (CRFs) for fractures taken either alone or in combination in the FRAX score were shown not to reliably predict fractures and/or osteoporosis (as defined by a T-score<-2.5) in early postmenopausal women. If DXA measurement is indicated in all women with CRFs for fractures, it can be proposed on a case-by-case basis, when knowledge of BMD is likely to condition the management of women at the beginning of menopause, particularly the benefit-risk balance of MHT. MHT prevents both bone loss and degradation of the bone microarchitecture in early menopause. It significantly reduces the risk of fracture at all bone sites by 20 to 40% regardless of basal level of risk with an estrogen-dependent dose-effect. Given the inter-individual variability in bone response, individual monitoring of the bone effect of MHT is warranted when prescribed for the prevention of osteoporosis. This monitoring is based on repeated measurement of lumbar and femoral BMD (on the same DXA measurement system) after 2years of MHT, the response criterion being no significant bone loss. Discontinuation of treatment is associated with a resumption of transient bone loss although there is a large variability in the rate of bone loss among women. Basically, there is a return to the level of fracture risk comparable to that of in untreated woman of the same age within 2 to 5years. Therefore, when MHT is prescribed for the prevention of osteoporosis in women with an increased risk at the beginning of menopause, measurement of BMD is recommended when MHT is stopped in order to consider further management of the risk of fracture whenever necessary (with possibly another anti-osteoporotic treatment).

Identification of Critical Functional Modules and Signaling Pathways in Osteoporosis

Background:

Osteoporosis is the most common bone metabolic disease. Abnormal osteoclast formation and resorption play a fundamental role in osteoporosis pathogenesis. Recent researches have greatly broadened our understanding of molecular mechanisms of osteoporosis. However, the molecular mechanisms leading to osteoporosis are still not entirely clear.

Objective:

The purpose of this work is to study the critical regulatory genes, functional modules, and signaling pathways.

Methods:

Differential expression analysis, network topology-based analysis, and overrepresentation enrichment analysis (ORA) were used to identify differentially expressed genes (DEGs), gene subnetworks, and signaling pathways related to osteoporosis, respectively.

Results:

Differential expression analysis identified DEGs, such as POGLUT1, DAPK3 and NFKBIA, associated with osteoclastogenesis, which highlighted Notch, apoptosis and NF-kB signaling pathways. Network topology-based analysis identified the upregulated subnetwork characterized by EXOSC8 and DIS3L from the RNA exosome complex, and the downregulated subnetwork composed of histone deacetylases and the cofactors, MORF4L1 and JDP2. Furthermore, the overrepresentation enrichment analysis highlighted that corticotrophin-releasing hormone signaling pathway might affect osteoclastogenesis through its component NR4A1, and suppressing osteoclast differentiation and osteoclast bone resorption with urocortin (UCN).

Conclusion:

Our systematic analysis not only discovered novel molecular mechanisms but also proposed potential drug targets for osteoporosis.

The association between renal function and BMD response to bisphosphonate treatment: Real-world cohort study using linked national registers

BACKGROUND

Management of osteoporosis given reduced renal function is one of the largest challenges in the bone clinic.

OBJECTIVES

Identify the cut-off for renal function below which there would be no overall BMD benefit associated with bisphosphonate use. Track safety outcomes resulting in hospital encounters.

METHODS

Population-based, observational register-linked study of BMD trajectories in adults from the island of Funen (pop 465,000) as a function of estimated creatinine clearance (CKD-epi), treatment and adherence to oBP. One laboratory performed all the biochemical analyses for the area while all DXA scans were in a central facility. For inclusion, patients were required to have both a DXA scan and an eGFR measurement (CKD-EPI) within 1 year prior to their study index date. Medication Possession Ratio (MPR) was calculated from national data.

RESULTS

Out of 6176 incident BP users, 1789 had eGFR and DXA measurements at appropriate timepoints for the planned analysis, while this was the case for 3908 of 29,336 non-users. Users of oBPs exhibited progressively smaller gains in BMD with decreasing renal function. However, for CKD stage 3A and better, the annual change in BMD was significantly more positive than in the non-user group at similar levels of renal function. In non-users, the average annual change in BMD was negative but largely unaffected by renal function down to stage 3B. There were no new cases of acute renal injury, glomerulonephritis or dialysis. The rate of new kidney transplantation was zero in non-users and 0.26 per 1000 PY in the BP user population. Hypocalcaemia encounters did not differ significantly from that seen in non-users.

CONCLUSIONS

The BMD changes observed in real-world users of oBP in this population based single-clinic are consistent with those observed in the original RCTs of alendronate. We noted a gradual decrease in the absolute gains in BMD in oBP users with decreasing renal function though there was no significant interaction - largely explained by low numbers of treated patients with poor renal function - between CKD stage and adherence driven BMD change. There were no cases of acute renal injury resulting in hospital encounters. More data is needed on the efficacy and safety of bisphosphonates in CKD stage 3B to 5 and prescribers should reconsider the low use of DXA in patients with renal function impairment now that a wider range of treatment options are available.

Assessment and hormonal management of osteoporosis

Postmenopausal osteoporosis is a frequent health issue in women. Because osteoporosis-related fractures cause a significant increase in mortality and morbidity, it is clinically important to identify as soon as possible women at increased risk for future fracture so that preventive measures can be instituted. At the beginning of menopause, evaluation of the subsequent risk of fracture is not so easy. Most screening tools fail to accurately identify those women who will fracture within the next 10 years. A history of a prior fracture and low bone mineral density are the only major consistently found predictors for the risk of fracture. On the other hand, it is no longer a question whether menopause hormone therapy is efficient not only to prevent postmenopausal bone loss but also the incidence of fragility fracture. Over the last years, utility of menopause hormone therapy for the prevention of osteoporosis has been questioned due to safety concerns. In light of the most recent reports on a more favorable benefit/risk balance than was initially claimed in early postmenopausal women, this needs to be reconsidered. Prevention of bone loss in those women with a moderate or slightly high risk of fracture is likely a strategy to reduce fracture risk in older women. Menopause hormone therapy must be considered as a true primary preventive therapy more than an anti-fracture therapy at an age when the risk of fracture is likely much lower than later in life. Only thereafter should other anti-osteoporotic medications be discussed in women still at high risk for fracture.

Predicting Future Hip Fractures on Routine Abdominal CT Using Opportunistic Osteoporosis Screening Measures: A Matched Case-Control Study

OBJECTIVE

Hip fracture is a major consequence of low bone mineral density, which is treatable but underdiagnosed. The purpose of this case-control study is to determine whether lumbar vertebral trabecular attenuation, vertebral compression fractures, and femoral neck T scores readily derived from abdominopelvic CT scans obtained for various indications are associated with future hip fragility fracture.

MATERIALS AND METHODS

A cohort of 204 patients with hip fracture (130 women and 74 men; mean age, 74.3 years) who had undergone abdominopelvic CT before fracture occurred (mean interval, 24.8 months) was compared with an age- and sex-matched control cohort without hip fracture. L1 trabecular attenuation, vertebral compression fractures of grades 2 and 3, and femoral neck T scores derived from asynchronous quantitative CT were recorded. The presence of one or more clinical risk factor for fracture was also recorded. Multivariate logistic regression models were used to determine the association of each measurement with the occurrence of hip fracture.

RESULTS

The mean L1 trabecular attenuation value, the presence of one or more vertebral compression fracture, and CT-derived femoral neck T scores were all significantly different in patients with hip fracture versus control subjects (p < 0.01). Logistic regression models showed a significant association of all measurements with hip fracture outcome after adjustments were made for age, sex, and the presence of one or more clinical risk factor. L1 trabecular attenuation and CT-derived femoral neck T scores showed moderate accuracy in differentiating case and control patients (AUC, 0.70 and 0.78, respectively).

CONCLUSION

L1 trabecular attenuation, CT-derived femoral neck T scores, and the presence of at least one vertebral compression fracture on CT are all associated with future hip fragility fracture in adults undergoing routine abdominopelvic CT for a variety of conditions.

Low-trauma fractures without osteoporosis

In clinical practice, areal bone mineral density (aBMD) is usually measured using dual-energy X-ray absorptiometry (DXA) to assess bone status in patients with or without osteoporotic fracture. As BMD has a Gaussian distribution, it is difficult to define a cutoff for osteoporosis diagnosis. Based on epidemiological considerations, WHO defined a DXA-based osteoporosis diagnosis with a T-score <-2.5. However, the majority of individuals who have low-trauma fractures do not have osteoporosis with DXA (i.e., T-score <-2.5), and some of them have no decreased BMD at all. Some medical conditions (spondyloarthropathies, chronic kidney disease and mineral bone disorder, diabetes, obesity) or drugs (glucocorticoids, aromatase inhibitors) are more prone to cause fractures with subnormal BMD. In the situation of fragility fractures with subnormal or normal BMD, clinicians face a difficulty as almost all the pharmacologic treatments have proved their efficacy in patients with low BMD. However, some data are available in post hoc analyses in patients with T score >-2. Overall, in patients with a previous fragility fracture (especially vertebra or hip), treatments appear to be effective. Thus, the authors recommend treating some patients with a major fragility fracture even if areal BMD T score is above -2.5.

A systematic review of intervention thresholds based on FRAX : A report prepared for the National Osteoporosis Guideline Group and the International Osteoporosis Foundation

This systematic review identified assessment guidelines for osteoporosis that incorporate FRAX. The rationale for intervention thresholds is given in a minority of papers. Intervention thresholds (fixed or age-dependent) need to be country-specific.

INTRODUCTION

In most assessment guidelines, treatment for osteoporosis is recommended in individuals with prior fragility fractures, especially fractures at spine and hip. However, for those without prior fractures, the intervention thresholds can be derived using different methods. The aim of this report was to undertake a systematic review of the available information on the use of FRAX® in assessment guidelines, in particular the setting of thresholds and their validation.

METHODS

We identified 120 guidelines or academic papers that incorporated FRAX of which 38 provided no clear statement on how the fracture probabilities derived are to be used in decision-making in clinical practice. The remainder recommended a fixed intervention threshold (n = 58), most commonly as a component of more complex guidance (e.g. bone mineral density (BMD) thresholds) or an age-dependent threshold (n = 22). Two guidelines have adopted both age-dependent and fixed thresholds.

RESULTS

Fixed probability thresholds have ranged from 4 to 20 % for a major fracture and 1.3-5 % for hip fracture. More than one half (39) of the 58 publications identified utilised a threshold probability of 20 % for a major osteoporotic fracture, many of which also mention a hip fracture probability of 3 % as an alternative intervention threshold. In nearly all instances, no rationale is provided other than that this was the threshold used by the National Osteoporosis Foundation of the USA. Where undertaken, fixed probability thresholds have been determined from tests of discrimination (Hong Kong), health economic assessment (USA, Switzerland), to match the prevalence of osteoporosis (China) or to align with pre-existing guidelines or reimbursement criteria (Japan, Poland). Age-dependent intervention thresholds, first developed by the National Osteoporosis Guideline Group (NOGG), are based on the rationale that if a woman with a prior fragility fracture is eligible for treatment, then, at any given age, a man or woman with the same fracture probability but in the absence of a previous fracture (i.e. at the 'fracture threshold') should also be eligible. Under current NOGG guidelines, based on age-dependent probability thresholds, inequalities in access to therapy arise especially at older ages (≥70 years) depending on the presence or absence of a prior fracture. An alternative threshold using a hybrid model reduces this disparity.

CONCLUSION

The use of FRAX (fixed or age-dependent thresholds) as the gateway to assessment identifies individuals at high risk more effectively than the use of BMD. However, the setting of intervention thresholds needs to be country-specific.

The global burden attributable to low bone mineral density

INTRODUCTION

The Global Burden of Disease Study 2010 estimated the worldwide health burden of 291 diseases and injuries and 67 risk factors by calculating disability-adjusted life years (DALYs). Osteoporosis was not considered as a disease, and bone mineral density (BMD) was analysed as a risk factor for fractures, which formed part of the health burden due to falls.

OBJECTIVES

To calculate (1) the global distribution of BMD, (2) its population attributable fraction (PAF) for fractures and subsequently for falls, and (3) the number of DALYs due to BMD.

METHODS

A systematic review was performed seeking population-based studies in which BMD was measured by dual-energy X-ray absorptiometry at the femoral neck in people aged 50 years and over. Age- and sex-specific mean ± SD BMD values (g/cm(2)) were extracted from eligible studies. Comparative risk assessment methodology was used to calculate PAFs of BMD for fractures. The theoretical minimum risk exposure distribution was estimated as the age- and sex-specific 90th centile from the Third National Health and Nutrition Examination Survey (NHANES III). Relative risks of fractures were obtained from a previous meta-analysis. Hospital data were used to calculate the fraction of the health burden of falls that was due to fractures.

RESULTS

Global deaths and DALYs attributable to low BMD increased from 103 000 and 3 125 000 in 1990 to 188 000 and 5 216 000 in 2010, respectively. The percentage of low BMD in the total global burden almost doubled from 1990 (0.12%) to 2010 (0.21%). Around one-third of falls-related deaths were attributable to low BMD.

CONCLUSIONS

Low BMD is responsible for a growing global health burden, only partially representative of the real burden of osteoporosis.

Performance of risk assessment instruments for predicting osteoporotic fracture risk: a systematic review

We systematically reviewed the literature on the performance of osteoporosis absolute fracture risk assessment instruments. Relatively few studies have evaluated the calibration of instruments in populations separate from their development cohorts, and findings are mixed. Many studies had methodological limitations making susceptibility to bias a concern.

INTRODUCTION

The aim of this study was to systematically review the literature on the performance of osteoporosis clinical fracture risk assessment instruments for predicting absolute fracture risk, or calibration, in populations other than their derivation cohorts.

METHODS

We performed a systematic review, and MEDLINE, Embase, Cochrane Library, and multiple other literature sources were searched. Inclusion and exclusion criteria were applied and data extracted, including information about study participants, study design, potential sources of bias, and predicted and observed fracture probabilities.

RESULTS

A total of 19,949 unique records were identified for review. Fourteen studies met inclusion criteria. There was substantial heterogeneity among included studies. Six studies assessed the WHO's Fracture Risk Assessment (FRAX) instrument in five separate cohorts, and a variety of risk assessment instruments were evaluated in the remainder of the studies. Approximately half found good instrument calibration, with observed fracture probabilities being close to predicted probabilities for different risk categories. Studies that assessed the calibration of FRAX found mixed performance in different populations. A similar proportion of studies that evaluated simple risk assessment instruments (≤5 variables) found good calibration when compared with studies that assessed complex instruments (>5 variables). Many studies had methodological features making them susceptible to bias.

CONCLUSIONS

Few studies have evaluated the performance or calibration of osteoporosis fracture risk assessment instruments in populations separate from their development cohorts. Findings are mixed, and many studies had methodological limitations making susceptibility to bias a possibility, raising concerns about use of these tools outside of the original derivation cohorts. Further studies are needed to assess the calibration of instruments in different populations prior to widespread use.

[What patients need to know about the risk of bone fracture and its prevention]

Post-menopausal osteoporosis is one of the classic complications of prolonged estrogen deficiency associated with menopause. It is defined as a state of the skeleton characterized by decreased bone strength with an increased risk of fracture. The natural history of osteoporosis and, in particular, the rapid increase in fracture recurrence after a first major fracture should justify a priori an approach for early detection of women at higher risk from the early postmenopausal phase. It is more of a chronic disease that requires support in the long term, in the absence of a truly curative treatment. Indeed, currently available therapies can at best reduce the incidence of fractures by about 50%, especially at the vertebral site, but do not cancel the disease. Moreover, duration of treatment is currently recommended for 5 to 10 years, which does not allow to consider that a single molecule could be taken "for the whole life". The fracture risk assessment based on the combination of densitometric measurement by DXA and the search for clinical risk factors is a prerequisite to any therapy. The first choice of treatment is especially important for a relatively young woman with high fracture risk. In early menopause (generally within the first decade of post-menopausal) and in the absence of contraindication, menopausal hormone therapy should remain the preferred option for first-line whenever possible. Raloxifene is an interesting alternative, due to its mechanisms of action and multiplicity of targets with, in particular, its preventive effect on the risk of estrogen receptor-positive breast cancer. It is only when there are contraindications to one or the other of these two molecules, that other osteoporosis treatments can be discussed. They should nevertheless be considered only in women whose 10-year-fracture risk is significantly increased. Indeed, it is mainly in this high risk of fracture, particularly because of an age greater than 65 years and a history of vertebral fracture, that their antifracture efficacy has been validated. In addition, it is mostly beyond this age that the question of the prevention of hip fracture has to be considered.

Development and validation of a tool for identifying women with low bone mineral density and low-impact fractures: the São Paulo Osteoporosis Risk Index (SAPORI)

The performance of the São Paulo Osteoporosis Risk Index (SAPORI) was tested in 1,915 women from the original cohort, São Paulo Osteoporosis Study (SAPOS) (N = 4332). This new tool was able to identify women with low bone density (spine and hip) and low-impact fracture, with an area under the receiving operator curve (ROC) of 0.831, 0.724, and 0.689, respectively.

INTRODUCTION

A number of studies have demonstrated the clinical relevance of risk factors for identifying individuals at risk of fracture (Fx) and osteoporosis (OP). The SAPOS is an epidemiological study for the assessment of risk factors for Fx and low bone density in women from the community of the metropolitan area of São Paulo, Brazil. The aim of the present study was to develop and validate a tool for identifying women at higher risk for OP and low-impact Fx.

METHODS

A total of 4,332 pre-, peri-, and postmenopausal women were analyzed through a questionnaire addressing risk factors for OP and Fx. All of them performed bone densitometry at the lumbar spine and proximal femur (DPX NT, GE-Lunar). Following the identification of the main risk factors for OP and Fx through multivariate and logistic regression, respectively, the SAPORI was designed and subsequently validated on a second cohort of 1,915 women from the metropolitan community of São Paulo. The performance of this tool was assessed through ROC analysis.

RESULTS

The main and significant risk factors associated with low bone density and low-impact Fx were low body weight, advanced age, Caucasian ethnicity, family history of hip Fx, current smoking, and chronic use of glucocorticosteroids. Hormonal replacement therapy and regular physical activity in the previous year played a protective role (p < 0.05). After the statistical adjustments, the SAPORI was able to identify women with low bone density (T-score ≤ -2 standard deviations) in the femur, with 91.4% sensitivity, 52% specificity, and an area under the ROC of 0.831 (p < 0.001). At the lumbar spine, the performance was similar (81.5% sensitivity, 50% specificity, and area under ROC of 0.724; p < 0.001). Regarding the identification of low-impact Fx, the sensitivity was 71%, the specificity was 52%, and the area under the ROC was 0.689 (p < 0.001).

CONCLUSION

The SAPORI is a simple, useful, fast, practice, and valid tool for identifying women at higher risk for low bone density and osteoporotic fractures.

Pitfalls in the external validation of FRAX

SUMMARY

Recent studies have evaluated the performance of FRAX® in independent cohorts. The interpretation of most is problematic for reasons summarised in this perspective.

INTRODUCTION

FRAX is an extensively validated assessment tool for the prediction of fracture in men and women. The aim of this study was to review the methods used since the launch of FRAX to further evaluate this instrument.

METHODS

This covers a critical review of studies investigating the calibration of FRAX or assessing its performance characteristics in external cohorts.

RESULTS

Most studies used inappropriate methodologies to compare the performance characteristics of FRAX with other models. These included discordant parameters of risk (comparing incidence with probabilities), comparison with internally derived predictors and inappropriate use and interpretation of receiver operating characteristic curves. These deficits markedly impair interpretation of these studies.

CONCLUSION

Cohort studies that have evaluated the performance of FRAX need to be interpreted with caution and preferably re-evaluated.

Are spontaneous fractures possible? An example of clinical application for personalised, multiscale neuro-musculo-skeletal modelling

Elderly frequently present variable degrees of osteopenia, sarcopenia, and neuromotor control degradation. Severely osteoporotic patients sometime fracture their femoral neck when falling. Is it possible that such fractures might occur without any fall, but rather spontaneously while the patient is performing normal movements such as level walking? The aim of this study was to verify if such spontaneous fractures are biomechanically possible, and in such case, which conditions of osteoporosis, sarcopenia, and neuromotor degradation could produce them. To the purpose, a probabilistic multiscale body-organ model validated against controlled experiments was used to predict the risk of spontaneous fractures in a population of 80-years old women, with normal weight and musculoskeletal anatomy, and variable degree of osteopenia, sarcopenia, and neuromotor control degradation. A multi-body inverse dynamics sub-model, coupled to a probabilistic neuromuscular sub-model, and to a femur finite element sub-model, formed the multiscale model, which was run within a Monte Carlo stochastic scheme, where the various parameters were varied randomly according to well defined distributions. The model predicted that neither extreme osteoporosis, nor extreme neuromotor degradation alone are sufficient to predict spontaneous fractures. However, when the two factors are combined an incidence of 0.4% of spontaneous fractures is predicted for the simulated population, which is consistent with clinical reports. When the model represented only severely osteoporotic patients, the incidence of spontaneous fractures increased to 29%. Thus, is biomechanically possible that spontaneous femoral neck fractures occur during level walking, due to a combination of severe osteoporosis and severe neuromotor degradation.

Fracture risk prediction using BMD and clinical risk factors in early postmenopausal women: sensitivity of the WHO FRAX tool

The aim of this prospective study was (1) to identify significant and independent clinical risk factors (CRFs) for major osteoporotic (OP) fracture among peri- and early postmenopausal women, (2) to assess, in this population, the discriminatory capacity of FRAX and bone mineral density (BMD) for the identification of women at high risk of fracture, and (3) to assess whether adding risk factors to either FRAX or BMD would improve discriminatory capacity. The study population included 2651 peri- and early postmenopausal women [mean age (+/- SD): 54 +/- 4 years] with a mean follow-up period of 13.4 years (+/-1.4 years). At baseline, a large set of CRFs was recorded, and vertebral BMD was measured (Lunar, DPX) in all women. Femoral neck BMD also was measured in 1399 women in addition to spine BMD. Women with current or past OP treatment for more than 3 months at baseline (n = 454) were excluded from the analyses. Over the follow-up period, 415 women sustained a first low-energy fracture, including 145 major OP fractures (108 wrist, 44 spine, 20 proximal humerus, and 13 hip). In Cox multivariate regression models, only 3 CRFs were significant predictors of a major OP fracture independent of BMD and age: a personal history of fracture, three or more pregnancies, and current postmenopausal hormone therapy. In the subsample of women who had a hip BMD measurement and who were not receiving OP therapy (including hormone-replacement therapy) at baseline, mean FRAX value was 3.8% (+/-2.4%). The overall discriminative value for fracture, as measured by the area under the Receiver Operating Characteristic (ROC) curve (AUC), was equal to 0.63 [95% confidence interval (CI) 0.56-0.69] and 0.66 (95% CI 0.60-0.73), respectively, for FRAX and hip BMD. Sensitivity of both tools was low (ie, around 50% for 30% of the women classified as the highest risk). Adding parity to the predictive model including FRAX or using a simple risk score based on the best predictive model in our population did not significantly improve the discriminatory capacity over BMD alone. Only a limited number of clinical risk factors were found associated with the risk of major OP fracture in peri- and early postmenopausal women. In this population, the FRAX tool, like other risk scores combining CRFs to either BMD or FRAX, had a poor sensitivity for fracture prediction and did not significantly improve the discriminatory value of hip BMD alone.

Factors influencing the treatment of osteoporosis following fragility fracture

Treatment rates of osteoporosis after fracture are very low. Women who suffer a fragility fracture have a greater chance of receiving anti-fracture treatment if they had low bone mineral density (BMD), a fracture at the hip, femur or pelvis, administration of calcium and vitamin D supplements and/or an age > or =60 years.

INTRODUCTION

This investigation identifies the predictors of osteoporosis treatment 6 to 8 months following fragility fracture in women >50 years of age.

METHODS

In this prospective cohort study, women were recruited 0 to 16 weeks following fracture and classified as having experienced fragility or traumatic fractures (phase 1). Six to 8 months following fracture, women completed a questionnaire on demographic features, clinical characteristics and risk factors for osteoporosis (phase 2). Osteoporosis treatment was defined as initiating anti-fracture therapy (bisphosphonate, raloxifene, nasal calcitonin and teriparatide) after fracture in those previously untreated.

RESULTS

Of the 1,273 women completing phase 1, 1,001 (79%) sustained a fragility fracture, and of these women, 738 were untreated for osteoporosis at phase 1 and completed the phase 2 questionnaire. Significant predictors of treatment included BMD result, fracture site, administration of calcium and vitamin D supplements at the time of fracture and age > or =60 years. All other risk factors for osteoporosis, such as fracture history after the age of 40 years, family history of osteoporosis and comorbidities did not significantly influence the treatment rate.

CONCLUSIONS

Physicians largely based their decision to treat on BMD results and not on the clinical event-fragility fracture.

Remaining lifetime and absolute 10-year probabilities of osteoporotic fracture in Swiss men and women

SUMMARY

Remaining lifetime and absolute 10-year probabilities for osteoporotic fractures were determined by gender, age, and BMD values. Remaining lifetime probability at age 50 years was 20.2% in men and 51.3% in women and increased with advancing age and decreasing BMD. The study validates the elements required to populate a Swiss-specific FRAX model.

INTRODUCTION

Switzerland belongs to high-risk countries for osteoporosis. Based on demographic projections, burden will still increase. We assessed remaining lifetime and absolute 10-year probabilities for osteoporotic fractures by gender, age and BMD in order to populate FRAX algorithm for Switzerland.

METHODS

Osteoporotic fracture incidence was determined from national epidemiological data for hospitalised fractured patients from the Swiss Federal Office of Statistics in 2000 and results of a prospective Swiss cohort with almost 5,000 fractured patients in 2006. Validated BMD-associated fracture risk was used together with national death incidence and risk tables to determine remaining lifetime and absolute 10-year fracture probabilities for hip and major osteoporotic (hip, spine, distal radius, proximal humerus) fractures.

RESULTS

Major osteoporotic fractures incidence was 773 and 2,078 per 100,000 men and women aged 50 and older. Corresponding remaining lifetime probabilities at age 50 were 20.2% and 51.3%. Hospitalisation for clinical spine, distal radius, and proximal humerus fractures reached 25%, 30% and 50%, respectively. Absolute 10-year probability of osteoporotic fracture increased with advancing age and decreasing BMD and was higher in women than in men.

CONCLUSION

This study validates the elements required to populate a Swiss-specific FRAX model, a country at highest risk for osteoporotic fractures.

Correlation between bone markers and bone mineral density in postmenopausal women with osteoporosis

OBJECTIVE

To study the relationship between bone markers and bone mineral density (BMD) in an effort to identify their utility in postmenopausal women with osteoporosis.

METHODS

Eighty-two consecutive postmenopausal women with untreated osteoporosis were included in the study. Forearm, spinal, and femoral BMD by dual-energy x-ray absorptiometry and markers of bone formation (serum osteocalcin and bone-specific alkaline phosphatase) and bone resorption (urinary free deoxypyridinoline) were measured in all patients. Patients with low serum vitamin D levels, secondary osteoporosis, or clinically significant systemic disease were excluded from the study. The patients were classified on the basis of BMD of the lumbar spine into the following 3 groups: mild (n = 23) (T score -2.5 through -3), moderate (n = 42) (T score -3.1 through -4), or severe (n = 17) (T score <or=-4.1) osteoporosis. One-way analysis of variance and Pearson correlation were used for statistical analysis, with a P value <.05 being considered significant.

RESULTS

Serum osteocalcin was significantly different among the 3 study groups (4.1 +/- 2.7, 4.5 +/- 3.1, and 6.7 +/- 5.6 ng/mL, respectively; P = .0349) and had a significant negative correlation with BMD (r2 = -0.0779; P = .0168). Other bone markers such as bone-specific alkaline phosphatase and urinary free deoxypyridinoline did not correlate with the underlying BMD.

CONCLUSION

In our study, osteocalcin was significantly correlated with BMD in postmenopausal women with osteoporosis. Other bone markers did not correlate with BMD. Further large-scale population data and analyses are needed to confirm these findings.

Estimation of absolute fracture risk among middle-aged and older men and women: the EPIC-Norfolk population cohort study

While estimates of relative risks associated with risk factors such as age and bone mineral density (BMD) may be of interest for etiologic and comparative purposes, clinical questions such as who might benefit most from preventive interventions or BMD monitoring depend on estimates of absolute fracture risk. The European prospective investigation into cancer (EPIC)-Norfolk study included 25,311 participants (11,476 men) aged 4,079 years in 1993-1997. All participants were followed for osteoporotic fractures to March 2007. Ten-year absolute risk of fracture in men and women were calculated using the baseline survivor function in multivariable Cox proportional-hazards models adjusting for age, sex, history of fractures, body mass index, smoking, and alcohol intake. In comparison of those without history of fracture versus those with history of fracture, the 10-year absolute risk of any fracture in men ranged from 1.0 vs. 1.2% at age 40 years to 3.0 vs. 4.4% at age 75 years. The respective estimates in women ranged from 0.7 vs. 1.0% at age 40 years to 9.3 vs. 17.2% at age 75 years. Statistically significant interaction between age and sex was found (P < 0.001), which contributed to the differences in predicted absolute fracture risks for men and women at different ages. Our study shows the need for population-specific data to develop efficient well calibrated algorithms for assessment of fracture risk. The interaction observed between sex and age points to the need for further prospective studies among men.

Proximal femur specimens: automated 3D trabecular bone mineral density analysis at multidetector CT--correlation with biomechanical strength measurement

PURPOSE

To prospectively evaluate an automated volume of interest (VOI)-fitting algorithm for quantitative computed tomography (CT) of proximal femur specimens, correlate bone mineral density (BMD) with biomechanically determined bone strength in vitro, and compare that correlation with those observed at dual-energy x-ray absorptiometry (DXA) measurement of BMD.

MATERIALS AND METHODS

The study was compliant with institutional and legislative requirements; donors had dedicated their body for education and research before death. Multidetector CT and DXA scans were acquired in 178 proximal femur specimens harvested from human cadavers (91 women, 87 men; mean age at death, 79 years +/- 10.2; range, 52-100 years). An automated VOI-fitting algorithm was used to calculate BMD and bone mineral content (BMC) in the head, neck, and trochanter from CT findings and pixel distribution parameters. The femur failure load (FL) was determined by using a mechanical test. Quantitative CT BMD, quantitative CT pixel distribution parameters, DXA BMD, and FL were correlated at multiple regression analysis.

RESULTS

Mean precision errors in quantitative CT BMD measurements at segmentation with repositioning were 0.56%, 2.26%, and 0.61% for the head, neck, and trochanter, respectively. For the head, neck, and trochanter, respectively, r values were 0.77, 0.53, and 0.59 for the correlation between quantitative CT BMD and FL and 0.74, 0.55, and 0.65 for the correlation between quantitative CT BMC and FL (P < .001). Values ranged from 0.77 to 0.80 for correlations between DXA BMD and FL and from 0.73 to 0.82 for correlations between DXA BMC and FL (P < .001). In a multiple regression model that included quantitative CT pixel distributions, adjusted multivariate correlation coefficient values for correlations with FL increased to up to 0.88.

CONCLUSION

Regional BMD of the proximal femur can be determined in vitro from quantitative CT data with high precision by using an automated VOI-fitting algorithm. The best multiple regression model for predicting FL included DXA BMD and regional quantitative CT BMD measurements.

The importance of calculating absolute rather than relative fracture risk

The relation between fracture risk and bone mineral density (BMD) is commonly expressed as a multiplicative factor which is said to represent the increase in risk for each standard deviation fall in BMD. This practice assumes that risk increases multiplicatively with each unit fall in bone density, which is not correct. Although odds increase multiplicatively, absolute risk, which lies between 0 and 1, cannot do so though it can be derived from odds by the term Odds/(1+Odds). This concept is illustrated in a prospective study of 1098 women over age 69 followed for 6 years in a calcium trial in which hip BMD was measured in the second year. 304 Women (27.6%) had prevalent fractures and 198 (18.1%) incident fractures with a significant association between them (P 0.005). Age-adjusted hip BMD and T-score were significantly lower in those with prevalent fractures than in those without (P 0.003) and significantly lower in those with incident fractures than in those without (P 0.001). When the data were analysed by univariate logistic regression, the fracture odds at zero T-score were 0.130 and the rise in odds for each unit fall in hip T-score was 1.55. When these odds were converted to risks, there was a progressive divergence between odds and risk at T-scores below zero. Multiple logistic regression yielded significant odds ratios of 1.47 for each 5-year increase in age, 1.47 for prevalent fracture and 1.49 for each unit fall in hip T-score. Calcium therapy was not significant. Poisson regression, logistic regression and Cox's proportional hazards yielded very similar outcomes when converted into absolute risks. A nomogram was constructed to enable clinicians to estimate the approximate 6-year fracture risk from hip T-score, age and prevalent fracture which can probably be applied (with appropriate correction) to men as well as to women. We conclude that multiplicative factors can be applied to odds but not to risk and that multipliers of risk tend to overstate the effect of continuous variables, such as age and T-score, particularly towards the end of their ranges.

Simulation-based cost-utility analysis of population screening-based alendronate use in Switzerland

A simulation model adopting a health system perspective showed population-based screening with DXA, followed by alendronate treatment of persons with osteoporosis, or with anamnestic fracture and osteopenia, to be cost-effective in Swiss postmenopausal women from age 70, but not in men.

INTRODUCTION

We assessed the cost-effectiveness of a population-based screen-and-treat strategy for osteoporosis (DXA followed by alendronate treatment if osteoporotic, or osteopenic in the presence of fracture), compared to no intervention, from the perspective of the Swiss health care system.

METHODS

A published Markov model assessed by first-order Monte Carlo simulation was refined to reflect the diagnostic process and treatment effects. Women and men entered the model at age 50. Main screening ages were 65, 75, and 85 years. Age at bone densitometry was flexible for persons fracturing before the main screening age. Realistic assumptions were made with respect to persistence with intended 5 years of alendronate treatment. The main outcome was cost per quality-adjusted life year (QALY) gained.

RESULTS

In women, costs per QALY were Swiss francs (CHF) 71,000, CHF 35,000, and CHF 28,000 for the main screening ages of 65, 75, and 85 years. The threshold of CHF 50,000 per QALY was reached between main screening ages 65 and 75 years. Population-based screening was not cost-effective in men.

CONCLUSION

Population-based DXA screening, followed by alendronate treatment in the presence of osteoporosis, or of fracture and osteopenia, is a cost-effective option in Swiss postmenopausal women after age 70.

Adjuvant endocrine treatment of early breast cancer

Endocrine therapy plays a pivotal role in the early treatment of estrogen receptor (ER)-positive breast cancer. Although evidence suggests that chemotherapy may work partly through ovarian ablation in young women who have ER-positive tumors, combined chemotherapy and endocrine therapy are generally advocated. In postmenopausal women, aromatase inhibition has become the new "gold standard" of treatment. More research is needed to define optimal regimens (aromatase inhibitor monotherapy versus tamoxifen sequential application), optimal duration of therapy and potential advantages of particular compounds. The optimal use of estrogen suppression (ovarian ablation with or without aromatase inhibition) and tamoxifen (administered sequentially or in concert with ovarian ablation) in premenopausal women has yet to be defined.

Ten-year risk of osteoporotic fractures in postmenopausal Chinese women according to clinical risk factors and BMD T-scores: a prospective study

Independent risk factors for osteoporotic fracture were identified for a Southern Chinese postmenopausal population. Clinical risk factor assessment with or without BMD measurement was shown to be an effective predictor of 10-yr risk of osteoporotic fracture and provides a more accessible tool for patient evaluation.

INTRODUCTION

Asian-specific data on risk factors for osteoporosis remain sparse. However, risk factor assessment, in addition to BMD measurement, is increasingly recognized as a reliable predictor of absolute osteoporotic fracture risk. The purpose of this prospective study was to determine the specific independent risk factors for osteoporotic fracture and to predict the 10-yr risk of osteoporotic fracture in the postmenopausal Southern Chinese population.

MATERIALS AND METHODS

A total of 1435 community-dwelling, postmenopausal, treatment-naive women were recruited. Baseline demographic characteristics and clinical risk factors were obtained, and BMD at the spine and hip was measured. Subjects were followed for outcomes of incident low trauma fracture. Ten-year risk of osteoporotic fracture was predicted from the risk factor assessment and BMD measurement by Cox proportional hazards models.

RESULTS

The mean age of subjects was 63.4 +/- 8.3 yr. After 5.0 +/- 2.3 yr (range, 1.0-11.0 yr) of follow-up, 80 nontraumatic new fractures were reported during follow-up. Eight independent clinical risk factors identified at baseline were found to be significant predictors of osteoporotic fracture, with the most important being use of walking aids (RR, 4.2; 95% CI, 2.7-6.7; p < 0.001) and a history of fall (RR, 4.0; 95% CI, 2.5-6.2; p < 0.001). Other predictive factors included being homebound, calcium intake < 400 mg/d, age > 65 yr, history of fracture, and BMI < 19 kg/cm(2). Subjects with three to eight clinical risk factors had a predicted 10-year risk of osteoporotic fracture of 25%, which increased to 30% if they also had total hip BMD T-score <or= -2.5.

CONCLUSIONS

Clinical risk factor assessment, with or without BMD measurement, is a reliable predictor of 10-year risk of osteoporotic fracture and may be particularly useful in regions or primary care clinics without access to bone densitometry equipment.

The difference between hazard and risk in the relation between bone density and fracture

The relation between fracture risk and bone density is frequently defined in terms of a relative hazard derived from the Cox proportional hazards model. The relative hazard is a multiplicative factor representing the rise in hazard for each standard deviation fall in bone mineral density, which has a typical value of about 1.5. It is not generally appreciated that this hazard may only be equated with absolute risk when risk is very low; at higher risk and over long periods, it is inappropriate to apply a multiplicative factor to absolute risk because risk has a range of 0-1 and cannot exceed unity. Here, we show how "hazard" can be converted to risk and how misleading the current practice of equating relative hazards with relative risks can be.

Is treatment of early postmenopausal women with bisphosphonates justified?

The decision to treat women in the early postmenopausal period has come under scrutiny because of the low occurrence of fractures in this population and the possible lack of cost-effectiveness for individual patients. This article focuses on the potential use of bisphosphonates for the prevention and treatment of osteoporosis in the early postmenopausal period. Studies have determined that there is a relationship between bisphosphonate treatment and bone mineral density (BMD) gains, even in women in the early postmenopausal period without a diagnosis of osteoporosis. These patients receive benefit from treatment, including improvements in BMD levels and fracture protection. Using BMD scores, rates of bone turnover, and risk-based diagnostic criteria as part of the decision to initiate therapy may allow for the identification of an early postmenopausal patient population that would benefit from preventative therapy. This would improve the cost-effectiveness of using bisphosphonates for the prevention of osteoporosis in this population. The evaluation of women at risk for developing osteoporosis should include an assessment of both BMD scores and additional risk factors. Early postmenopausal women who are in a high-risk group should be considered candidates to receive bisphosphonate therapy.