Do we need bone mineral density to estimate osteoporotic fracture risk? A 10-year prospective multicentre validation study

A systematic review on the performance of fracture risk assessment tools: FRAX, DeFRA, FRA-HS

PURPOSE

Preventing fragility fractures by treating osteoporosis may reduce disability and mortality worldwide. Algorithms combining clinical risk factors with bone mineral density have been developed to better estimate fracture risk and possible treatment thresholds. This systematic review supported panel members of the Italian Fragility Fracture Guidelines in recommending the use of best-performant tool. The clinical performance of the three most used fracture risk assessment tools (DeFRA, FRAX, and FRA-HS) was assessed in at-risk patients.

METHODS

PubMed, Embase, and Cochrane Library were searched till December 2020 for studies investigating risk assessment tools for predicting major osteoporotic or hip fractures in patients with osteoporosis or fragility fractures. Sensitivity (Sn), specificity (Sp), and areas under the curve (AUCs) were evaluated for all tools at different thresholds. Quality assessment was performed using the Quality Assessment of Diagnostic Accuracy Studies-2; certainty of evidence (CoE) was evaluated using the Grading of Recommendations Assessment, Development and Evaluation approach.

RESULTS

Forty-three articles were considered (40, 1, and 2 for FRAX, FRA-HS, and DeFRA, respectively), with the CoE ranging from very low to high quality. A reduction of Sn and increase of Sp for major osteoporotic fractures were observed among women and the entire population with cut-off augmentation. No significant differences were found on comparing FRAX to DeFRA in women (AUC 59-88% vs. 74%) and diabetics (AUC 73% vs. 89%). FRAX demonstrated non-significantly better discriminatory power than FRA-HS among men.

CONCLUSION

The task force formulated appropriate recommendations on the use of any fracture risk assessment tools in patients with or at risk of fragility fractures, since no statistically significant differences emerged across different prediction tools.

Screening for the primary prevention of fragility fractures among adults aged 40 years and older in primary care: systematic reviews of the effects and acceptability of screening and treatment, and the accuracy of risk prediction tools

BACKGROUND

To inform recommendations by the Canadian Task Force on Preventive Health Care, we reviewed evidence on the benefits, harms, and acceptability of screening and treatment, and on the accuracy of risk prediction tools for the primary prevention of fragility fractures among adults aged 40 years and older in primary care.

METHODS

For screening effectiveness, accuracy of risk prediction tools, and treatment benefits, our search methods involved integrating studies published up to 2016 from an existing systematic review. Then, to locate more recent studies and any evidence relating to acceptability and treatment harms, we searched online databases (2016 to April 4, 2022 [screening] or to June 1, 2021 [predictive accuracy]; 1995 to June 1, 2021, for acceptability; 2016 to March 2, 2020, for treatment benefits; 2015 to June 24, 2020, for treatment harms), trial registries and gray literature, and hand-searched reviews, guidelines, and the included studies. Two reviewers selected studies, extracted results, and appraised risk of bias, with disagreements resolved by consensus or a third reviewer. The overview of reviews on treatment harms relied on one reviewer, with verification of data by another reviewer to correct errors and omissions. When appropriate, study results were pooled using random effects meta-analysis; otherwise, findings were described narratively. Evidence certainty was rated according to the GRADE approach.

RESULTS

We included 4 randomized controlled trials (RCTs) and 1 controlled clinical trial (CCT) for the benefits and harms of screening, 1 RCT for comparative benefits and harms of different screening strategies, 32 validation cohort studies for the calibration of risk prediction tools (26 of these reporting on the Fracture Risk Assessment Tool without [i.e., clinical FRAX], or with the inclusion of bone mineral density (BMD) results [i.e., FRAX + BMD]), 27 RCTs for the benefits of treatment, 10 systematic reviews for the harms of treatment, and 12 studies for the acceptability of screening or initiating treatment. In females aged 65 years and older who are willing to independently complete a mailed fracture risk questionnaire (referred to as "selected population"), 2-step screening using a risk assessment tool with or without measurement of BMD probably (moderate certainty) reduces the risk of hip fractures (3 RCTs and 1 CCT, n = 43,736, absolute risk reduction [ARD] = 6.2 fewer in 1000, 95% CI 9.0-2.8 fewer, number needed to screen [NNS] = 161) and clinical fragility fractures (3 RCTs, n = 42,009, ARD = 5.9 fewer in 1000, 95% CI 10.9-0.8 fewer, NNS = 169). It probably does not reduce all-cause mortality (2 RCTs and 1 CCT, n = 26,511, ARD = no difference in 1000, 95% CI 7.1 fewer to 5.3 more) and may (low certainty) not affect health-related quality of life. Benefits for fracture outcomes were not replicated in an offer-to-screen population where the rate of response to mailed screening questionnaires was low. For females aged 68-80 years, population screening may not reduce the risk of hip fractures (1 RCT, n = 34,229, ARD = 0.3 fewer in 1000, 95% CI 4.2 fewer to 3.9 more) or clinical fragility fractures (1 RCT, n = 34,229, ARD = 1.0 fewer in 1000, 95% CI 8.0 fewer to 6.0 more) over 5 years of follow-up. The evidence for serious adverse events among all patients and for all outcomes among males and younger females (<65 years) is very uncertain. We defined overdiagnosis as the identification of high risk in individuals who, if not screened, would never have known that they were at risk and would never have experienced a fragility fracture. This was not directly reported in any of the trials. Estimates using data available in the trials suggest that among "selected" females offered screening, 12% of those meeting age-specific treatment thresholds based on clinical FRAX 10-year hip fracture risk, and 19% of those meeting thresholds based on clinical FRAX 10-year major osteoporotic fracture risk, may be overdiagnosed as being at high risk of fracture. Of those identified as being at high clinical FRAX 10-year hip fracture risk and who were referred for BMD assessment, 24% may be overdiagnosed. One RCT (n = 9268) provided evidence comparing 1-step to 2-step screening among postmenopausal females, but the evidence from this trial was very uncertain. For the calibration of risk prediction tools, evidence from three Canadian studies (n = 67,611) without serious risk of bias concerns indicates that clinical FRAX-Canada may be well calibrated for the 10-year prediction of hip fractures (observed-to-expected fracture ratio [O:E] = 1.13, 95% CI 0.74-1.72, I² = 89.2%), and is probably well calibrated for the 10-year prediction of clinical fragility fractures (O:E = 1.10, 95% CI 1.01-1.20, I² = 50.4%), both leading to some underestimation of the observed risk. Data from these same studies (n = 61,156) showed that FRAX-Canada with BMD may perform poorly to estimate 10-year hip fracture risk (O:E = 1.31, 95% CI 0.91-2.13, I² = 92.7%), but is probably well calibrated for the 10-year prediction of clinical fragility fractures, with some underestimation of the observed risk (O:E 1.16, 95% CI 1.12-1.20, I² = 0%). The Canadian Association of Radiologists and Osteoporosis Canada Risk Assessment (CAROC) tool may be well calibrated to predict a category of risk for 10-year clinical fractures (low, moderate, or high risk; 1 study, n = 34,060). The evidence for most other tools was limited, or in the case of FRAX tools calibrated for countries other than Canada, very uncertain due to serious risk of bias concerns and large inconsistency in findings across studies. Postmenopausal females in a primary prevention population defined as <50% prevalence of prior fragility fracture (median 16.9%, range 0 to 48% when reported in the trials) and at risk of fragility fracture, treatment with bisphosphonates as a class (median 2 years, range 1-6 years) probably reduces the risk of clinical fragility fractures (19 RCTs, n = 22,482, ARD = 11.1 fewer in 1000, 95% CI 15.0-6.6 fewer, [number needed to treat for an additional beneficial outcome] NNT = 90), and may reduce the risk of hip fractures (14 RCTs, n = 21,038, ARD = 2.9 fewer in 1000, 95% CI 4.6-0.9 fewer, NNT = 345) and clinical vertebral fractures (11 RCTs, n = 8921, ARD = 10.0 fewer in 1000, 95% CI 14.0-3.9 fewer, NNT = 100); it may not reduce all-cause mortality. There is low certainty evidence of little-to-no reduction in hip fractures with any individual bisphosphonate, but all provided evidence of decreased risk of clinical fragility fractures (moderate certainty for alendronate [NNT=68] and zoledronic acid [NNT=50], low certainty for risedronate [NNT=128]) among postmenopausal females. Evidence for an impact on risk of clinical vertebral fractures is very uncertain for alendronate and risedronate; zoledronic acid may reduce the risk of this outcome (4 RCTs, n = 2367, ARD = 18.7 fewer in 1000, 95% CI 25.6-6.6 fewer, NNT = 54) for postmenopausal females. Denosumab probably reduces the risk of clinical fragility fractures (6 RCTs, n = 9473, ARD = 9.1 fewer in 1000, 95% CI 12.1-5.6 fewer, NNT = 110) and clinical vertebral fractures (4 RCTs, n = 8639, ARD = 16.0 fewer in 1000, 95% CI 18.6-12.1 fewer, NNT=62), but may make little-to-no difference in the risk of hip fractures among postmenopausal females. Denosumab probably makes little-to-no difference in the risk of all-cause mortality or health-related quality of life among postmenopausal females. Evidence in males is limited to two trials (1 zoledronic acid, 1 denosumab); in this population, zoledronic acid may make little-to-no difference in the risk of hip or clinical fragility fractures, and evidence for all-cause mortality is very uncertain. The evidence for treatment with denosumab in males is very uncertain for all fracture outcomes (hip, clinical fragility, clinical vertebral) and all-cause mortality. There is moderate certainty evidence that treatment causes a small number of patients to experience a non-serious adverse event, notably non-serious gastrointestinal events (e.g., abdominal pain, reflux) with alendronate (50 RCTs, n = 22,549, ARD = 16.3 more in 1000, 95% CI 2.4-31.3 more, [number needed to treat for an additional harmful outcome] NNH = 61) but not with risedronate; influenza-like symptoms with zoledronic acid (5 RCTs, n = 10,695, ARD = 142.5 more in 1000, 95% CI 105.5-188.5 more, NNH = 7); and non-serious gastrointestinal adverse events (3 RCTs, n = 8454, ARD = 64.5 more in 1000, 95% CI 26.4-13.3 more, NNH = 16), dermatologic adverse events (3 RCTs, n = 8454, ARD = 15.6 more in 1000, 95% CI 7.6-27.0 more, NNH = 64), and infections (any severity; 4 RCTs, n = 8691, ARD = 1.8 more in 1000, 95% CI 0.1-4.0 more, NNH = 556) with denosumab. For serious adverse events overall and specific to stroke and myocardial infarction, treatment with bisphosphonates probably makes little-to-no difference; evidence for other specific serious harms was less certain or not available. There was low certainty evidence for an increased risk for the rare occurrence of atypical femoral fractures (0.06 to 0.08 more in 1000) and osteonecrosis of the jaw (0.22 more in 1000) with bisphosphonates (most evidence for alendronate). The evidence for these rare outcomes and for rebound fractures with denosumab was very uncertain. Younger (lower risk) females have high willingness to be screened. A minority of postmenopausal females at increased risk for fracture may accept treatment. Further, there is large heterogeneity in the level of risk at which patients may be accepting of initiating treatment, and treatment effects appear to be overestimated.

CONCLUSION

An offer of 2-step screening with risk assessment and BMD measurement to selected postmenopausal females with low prevalence of prior fracture probably results in a small reduction in the risk of clinical fragility fracture and hip fracture compared to no screening. These findings were most applicable to the use of clinical FRAX for risk assessment and were not replicated in the offer-to-screen population where the rate of response to mailed screening questionnaires was low. Limited direct evidence on harms of screening were available; using study data to provide estimates, there may be a moderate degree of overdiagnosis of high risk for fracture to consider. The evidence for younger females and males is very limited. The benefits of screening and treatment need to be weighed against the potential for harm; patient views on the acceptability of treatment are highly variable.

SYSTEMATIC REVIEW REGISTRATION

International Prospective Register of Systematic Reviews (PROSPERO): CRD42019123767.

Discrepancies Between Osteoporotic Fracture Evaluations in Men Based on German (DVO) Osteoporosis Guidelines or the FRAX Score

INTRODUCTION

Established scores estimate 10-year fracture risk in osteoporosis to assist with treatment recommendations. This study compared the risk probabilities of major osteoporotic and hip fractures calculated by the FRAX tool with those of the DVO score, established in German-speaking countries.

MATERIAL AND METHODS

This seven-year retrospective study analyzed data of 125 male patients (mean age: 59.2±10.7 years) evaluated for osteoporosis. For the DVO score, the therapy threshold of>30% for vertebral and hip fractures suggested by DVO guidelines was implemented. We calculated fracture risks based on FRAX scores with aBMD and applied a common therapy threshold of≥3% for hip fracture and subsequently determined the "DVO-equivalent risk level" for FRAX-based assessment that would identify as many male patients as identified by the DVO score.

RESULTS

Based on DVO score, 60.0% of patients had a 10-year risk of hip and vertebral fractures>30%. The recommendations for individuals based on FRAX scores for hip fracture with aBMD with risk≥3% overlapped with those based on DVO score in 36% of patients. Patients identified for treatment only by DVO score presented a higher percentage of spine fractures (65 vs. 41%). The thresholds for this "DVO-equivalent risk level" for 'FRAX with aBMD' was estimated to be≥6.7% for major osteoporotic fracture and≥2.1% for hip fracture.This study demonstrates that the DVO score was more sensitive than the FRAX score for patients with prevalent spinal fractures. We suggest considering the appropriate score and therapy threshold carefully in the daily care of male patients.

Executive summary: Italian guidelines for diagnosis, risk stratification, and care continuity of fragility fractures 2021

Background

Fragility fractures are a major public health concern owing to their worrying and growing burden and their onerous burden upon health systems. There is now a substantial body of evidence that individuals who have already suffered a fragility fracture are at a greater risk for further fractures, thus suggesting the potential for secondary prevention in this field.

Purpose

This guideline aims to provide evidence-based recommendations for recognizing, stratifying the risk, treating, and managing patients with fragility fracture. This is a summary version of the full Italian guideline.

Methods

The Italian Fragility Fracture Team appointed by the Italian National Health Institute was employed from January 2020 to February 2021 to (i) identify previously published systematic reviews and guidelines on the field, (ii) formulate relevant clinical questions, (iii) systematically review literature and summarize evidence, (iv) draft the Evidence to Decision Framework, and (v) formulate recommendations.

Results

Overall, 351 original papers were included in our systematic review to answer six clinical questions. Recommendations were categorized into issues concerning (i) frailty recognition as the cause of bone fracture, (ii) (re)fracture risk assessment, for prioritizing interventions, and (iii) treatment and management of patients experiencing fragility fractures. Six recommendations were overall developed, of which one, four, and one were of high, moderate, and low quality, respectively.

Conclusions

The current guidelines provide guidance to support individualized management of patients experiencing non-traumatic bone fracture to benefit from secondary prevention of (re)fracture. Although our recommendations are based on the best available evidence, questionable quality evidence is still available for some relevant clinical questions, so future research has the potential to reduce uncertainty about the effects of intervention and the reasons for doing so at a reasonable cost.

The role and place of the FRAX calculator in initiation osteoporosis treatment: an analysis of the osteoporosis center registry

Background: The growing frequency of fractures associated with osteoporosis, the significant costs of their treatment, disability and increased mortality make it an important and urgent task to optimize the diagnosis and treatment of osteoporosis in the Russian Federation.

Aim: The aim of this study was analyzed of using modern diagnostic criteria for osteoporosis by specialists when they making a clinical decision to initiate treatment for osteoporosis, including an estimate of the 10-year probability of fractures according to FRAX.

Materials and methods: The study was conducted in the city consultative and diagnostic center for the prevention of osteoporosis, St. Petersburg. The register of the osteoporosis center for 2018–2021 was used to select patients for the study. Based on the analysis of registry data, a sample of 362 patients with newly diagnosed osteoporosis was obtained. In the resulting sample, the existing FRAX value was assessed on the therapeutic intervention threshold graph, all of them analyzed the primary medical documentation, as well as the available DXA densitometry data.

Results: In this study, we assessed the place of FRAX 10-year risk of major osteoporotic fractures in the clinical decision of an osteoporosis specialist to start anti-osteoporosis therapy, in this case taken as the «gold standard». The study found that a positive FRAX score had a high predictive value of 100%. In contrast, the negative predictive value was very low (19.5%): a FRAX value below the intervention threshold did not guarantee a truly low fracture risk and no need to start osteoporosis treatment.

Conclusion: Despite the fact that both densitometry and FRAX have significant limitations in use, and cannot identify all patients with a high risk of fractures, their combined use increases the prognostic value of the methods. FRAX technology in routine practice allows, in addition to clinical and instrumental methods for diagnosing high-risk fractures, to identify candidates for the treatment of osteoporosis, and should be used in accordance with clinical recommendations.

Update of the fracture risk prediction tool FRAX: a systematic review of potential cohorts and analysis plan

We describe the collection of cohorts together with the analysis plan for an update of the fracture risk prediction tool FRAX with respect to current and novel risk factors. The resource comprises 2,138,428 participants with a follow-up of approximately 20 million person-years and 116,117 documented incident major osteoporotic fractures.

INTRODUCTION

The availability of the fracture risk assessment tool FRAX® has substantially enhanced the targeting of treatment to those at high risk of fracture with FRAX now incorporated into more than 100 clinical osteoporosis guidelines worldwide. The aim of this study is to determine whether the current algorithms can be further optimised with respect to current and novel risk factors.

METHODS

A computerised literature search was performed in PubMed from inception until May 17, 2019, to identify eligible cohorts for updating the FRAX coefficients. Additionally, we searched the abstracts of conference proceedings of the American Society for Bone and Mineral Research, European Calcified Tissue Society and World Congress of Osteoporosis. Prospective cohort studies with data on baseline clinical risk factors and incident fractures were eligible.

RESULTS

Of the 836 records retrieved, 53 were selected for full-text assessment after screening on title and abstract. Twelve cohorts were deemed eligible and of these, 4 novel cohorts were identified. These cohorts, together with 60 previously identified cohorts, will provide the resource for constructing an updated version of FRAX comprising 2,138,428 participants with a follow-up of approximately 20 million person-years and 116,117 documented incident major osteoporotic fractures. For each known and candidate risk factor, multivariate hazard functions for hip fracture, major osteoporotic fracture and death will be tested using extended Poisson regression. Sex- and/or ethnicity-specific differences in the weights of the risk factors will be investigated. After meta-analyses of the cohort-specific beta coefficients for each risk factor, models comprising 10-year probability of hip and major osteoporotic fracture, with or without femoral neck bone mineral density, will be computed.

CONCLUSIONS

These assembled cohorts and described models will provide the framework for an updated FRAX tool enabling enhanced assessment of fracture risk (PROSPERO (CRD42021227266)).

Risk of osteoporotic fracture in women using the FRAX tool with and without bone mineral density score in patients followed at a tertiary outpatient clinic ‒ An observational study

OBJECTIVES

Fragility fractures increase morbidity and mortality. Adding assessment of clinical risk factors independently or as a previous step to Bone Densitometry (BD) should provide better accuracy in fracture risk prediction. FRAX tool might be used to stratify patients in order to rationalize the need for BD and risk classification. The primary objective of this study is to describe and perform comparisons between the estimated risk of fractures in 10 years using the FRAX calculator based on clinical factors with and without BD results for women aged 40 or more with clinical diseases monitored in tertiary care service in internal medicine.

METHODS

Cross-sectional. Women over 40 years with BD in the previous year. After medical chart review, identification of risk factors and risk estimations using FRAX-BRAZIL with (FRAX BDI) and without (FRAX BDNI) the inclusion of T-score.

RESULTS

239 women. Age 65 ± 10.35 years. BMI 29.68 ± 6.27kg/m2.

RISK FACTORS

32(13.4%) previous fractures; 23 (9.6%) current smoking; 78 (32.6%) corticosteroids use; 44 (18.4%) rheumatoid arthritis; 38 (15.9%) secondary causes; FRAX scores were higher when BD was not included. Spearman correlation coefficients between FRAX BDNI and FRAX BDI for major fractures r = 0.793 (95% CI 0.7388‒0.836). For hip fractures r = 0.6922 (95% CI 0.6174‒0.75446) CONCLUSION: Using FRAX to estimate 10-year fracture risk without BD data might be a reliable tool for screening, even for patients with a high prevalence of risk factors, improving accessibility and equity in health systems. The present study's data suggest an overestimation of fracture risk with FRAX BDNI, suggesting that it is safe to be widely used as a screening tool.

Evaluating the performance of the Charlson Comorbidity Index (CCI) in fracture risk prediction and developing a new Charlson Fracture Index (CFI): a register-based cohort study

The Charlson Comorbidity Index (CCI) may be applicable for predicting fracture risk since several diagnoses from the index are predictors of fracture. Main results were that the CCI was updated to predict risk of hip fracture with fair precision and that the index could be useful in detecting high-risk individuals.

PURPOSE

Several of the Charlson Comorbidity Index (CCI) diagnoses are validated predictors of fracture. The purpose of this study was to evaluate the performance of the CCI 1987 by Charlson et al. and of the CCI 2011 by Quan et al. in predicting major osteoporotic fracture (MOF) and hip fracture (HF). Furthermore, it was examined whether the index could be modified to improve fracture risk prediction.

METHODS

The study population included the entire Danish population aged 45 + years as per January 1, 2018. The cohort was split randomly 50/50 into a development and a validation cohort. CCI diagnoses and fracture outcomes were identified from hospital diagnoses. The weighting of diagnoses was updated in a new Charlson Fracture Index (CFI) using multivariable logistic regression. Predictive capabilities of the CCI 1987, the updated CCI 2011 and the new Charlson Fracture index were evaluated in the validation cohort by receiver operating characteristics (ROC) curves and area under the curve (AUC).

RESULTS

In the validation cohort, the 1987 and 2011 CCIs resulted in AUCs below or around 0.7 in prediction of MOF and HF in both sexes. The CFI resulted in AUCs < 0.7 in prediction of MOF in both sexes. In prediction of HF, the CFI resulted in AUC of 0.755 (95% CI 0.749; 0.761) in women and 0.782 (95% CI 0.772; 0.793) in men.

CONCLUSION

The 1987 and 2011 CCIs showed overall poor accuracy in fracture risk prediction. The CFI showed fair accuracy in prediction of HF in women and in men.

Role of calcium and phosphorous concentration as an intrinsic factor in the development of skull fracture following road traffic accidents

INTRODUCTION

Traumatic brain injury (TBI) or head injury is one of the leading causes of morbidity and mortality globally. TBI includes a fractured skull as an indicator of insult which can affect the treatment outcome as well. The development of any fracture depends on a combination of factors defining the intrinsic properties of the bone and the extrinsic factors related to the impact. A decrease in bone mass secondary to deficiency of calcium (Ca) and phosphorus (P) can be a significant factor intrinsic to the skull bone, which can modulate the outcome of the impact by increasing the susceptibility of bones towards fractures. We undertook this research to find out whether or not the Ca and P concentration in skull bone has a role to play as an intrinsic factor, in the development of skull fracture following Road Traffic Accidents (RTAs).

METHODOLOGY

In this case-control study conducted for two years, we collected 94 bone samples, i.e. 47 each, from skull bones with head injuries following RTA, with (case) and without (control) fracture of the skull. The elemental analyses for the bony concentration of Ca and P in both the groups were then compared using energy dispersive X-ray (EDX). Unpaired t-test and Fisher's exact test was used for statistical analysis.

RESULTS

The elemental analysis of bones provided evidence that suggests that whilst; Ca is the only mineral that appears to have a significant correlation with the development of fracture skull, the overall Ca: P ratio of less than 1.99 increases the chances of skull fracture by 3.9 times.

CONCLUSIONS

Both individual bony Ca concentration and Ca: P ratio can be regarded as important intrinsic factors for the development of skull fracture.

Fracture Risk Assessment Tool May Not Indicate Bone Fragility in Women With Type 2 Diabetes

BACKGROUND

Diabetes carries a known risk of bone fracture despite high bone mineral density (BMD). The fracture risk assessment tool (FRAX) predicts the 10-year major osteoporotic fracture risk and hip fracture risk. We investigated the effects of clinical parameters on the FRAX score and evaluated the validity of FRAX for evaluating current bone fragility in diabetes subjects.

MATERIALS AND METHODS

Forty-seven thousand, three hundred eighty-nine Japanese women participated in the Chiba bone survey, a population-based, multicenter, cross-sectional study of postmenopausal osteoporosis; we estimated FRAX scores without BMD and compared scores between subjects with and without type 2 diabetes.

RESULTS

Mean FRAX major osteoporotic fracture risk was significantly higher in the diabetes group. A multiple regression model demonstrated some clinical parameters that affected the FRAX score and, after adjusting for such parameters, the FRAX score was not significantly different between the diabetes and nondiabetes groups, although the type 2 diabetes rate was significantly higher in subjects with a fracture in the past 5 years, which reflected current bone fragility. After adjusting for clinical parameters, the diabetes rate remained significantly higher in subjects with a fracture in the past 5 years, confirming that type 2 diabetes influences current bone fragility. Our study demonstrated that type 2 diabetes truly carries a risk of bone fracture, but adjusted FRAX major osteoporotic fracture risk is not significantly different between subjects with and without type 2 diabetes.

CONCLUSIONS

The FRAX major osteoporotic fracture risk without BMD does not correctly indicate current bone fragility in Japanese middle-aged women with type 2 diabetes.

Are blood lipids risk factors for fracture? Integrative evidence from instrumental variable causal inference and mediation analysis using genetic data

BACKGROUND

The relationship between lipids and the risk of fracture is currently controversial and whether such association is causal remains elusive.

METHODS

We performed two-sample inverse variance weighted (IVW) Mendelian randomization (MR) analyses to evaluate causal effects of four lipids (i.e. high-density lipoprotein cholesterol [HDL], low-density lipoprotein cholesterol [LDL], total cholesterol [TC] and triglyceride [TG]) on fracture or bone mineral density (BMD) with summary statistics from large scale genome-wide association studies (up to ~190,000 for lipids, ~66,628 for BMD and ~53,000 for fracture). We validated our MR results with extensive sensitive analyses including MR-PRESSO and MR-Egger regression. Multivariable analyses were implemented to investigate whether other lipids (i.e. LDL and TG) may confound the causal effect of HDL on fracture and mediation analyses were conducted to assess indirect effects of lipids on fracture mediated by BMD.

RESULTS

The IVW MR showed there existed a statistically significant association between HDL and fracture, with the odd ratio (OR) per standard deviation change of HDL on fracture being 1.12 (95% CI: 1.02-1.22, p = 1.20E-02). HDL was also detected to be causally associated with BMD (beta = -0.116; 95% CI: -0.182 ~ -0.050, p = 5.47E-04). These associations were further confirmed by the weighted median and maximum likelihood methods, with the MR-Egger regression removing the possibility of pleiotropy and the multivariable analysis excluding the confounding effect of other lipids on HDL. Negative associations of HDL with BMD among the elderly and with BMD at the lumbar spine were also discovered. However, no causal associations were detected between other lipids (OR = 0.87, 95% CI: 0.74-1.03, p = .107 for LDL; OR = 1.03; 95% CI: 0.88-1.21, p = .696 for TC and OR = 1.04; 95% CI: 0.90-1.20, p = .610 for TG) and fracture; whereas TG was positively associated BMD (beta = 0.184; 95% CI: 0.048-0.319, p = 7.93E-03). Finally, the mediation effect of BMD was estimated to be -0.116 (95% CI: -0.182 to -0.05, p = 5.47E-04) for HDL or 0.184 (95% CI: 0.048-0.319, p = 7.93E-03) for TG, implying HDL and TG could be indirectly associated with fracture risk via the pathway of BMD.

CONCLUSION

Our study is supportive of the causal relationship between HDL and fracture but offers little direct evidence for causal associations between other lipids and fracture, and further reveals HDL and TG may have an indirect influence on fracture mediated by BMD.

Elevated Serum 25-Hydroxyvitamin D Levels Are Associated with Improved Bone Formation and Micro-Structural Measures in Elderly Hip Fracture Patients

Vitamin D, along with calcium, is generally considered necessary for bone health and reduction of fractures. However, he effects of improving vitamin D status have not always been observed to improve bone mineral density (BMD). We have investigated whether varying vitamin D status in humans, as measured by serum 25(OH)D levels, relate to micro-structural and histomorphetric measures of bone quality and quantity, rather than density. Intertrochanteric trabecular bone biopsies and serum samples were collected from patients undergoing hip arthroplasty (65 females, 38 males, mean age 84.8 ± 8.3 years) at Royal Adelaide Hospital. Estimated GFR, serum ionized calcium, alkaline phosphatase, albumin, supplement and medication intake prior to surgery were taken from patient case records. Serum 25(OH)D, 1,25(OH)2D, and parathyroid hormone (PTH) levels were measured by immunoassays. Trabecular bone structural indices were determined by high-resolution micro-CT. Mean wall thickness (MWT) was measured on toluidine blue-stained histological sections. Bone mRNA levels for vitamin D metabolising enzymes CYP27B1 and CYP24A1 were measured by qRT-PCR. While serum 25(OH)D levels did not associate with bone volume/tissue volume (BV/TV%), serum 25(OH)D levels were strongly and independently associated with MWT (r = 0.81 p < 0.0001) with values significantly greater in patients with higher serum 25(OH)D levels. Furthermore, serum 25(OH)D levels were negatively associated with Bone Surface/Bone Volume (BS/BV) (r = −0.206, p < 0.05) and together with bone CYP27B1 and CYP24A1 mRNA accounted for 10% of the variability of BS/BV (p = 0.001). These data demonstrate that serum 25(OH)D is an independent positive predictor of micro-structural and bone formation measures and may be dependent, in part, on its metabolism within the bone.

Effects of Hip Structure Analysis Variables on Hip Fracture: A Propensity Score Matching Study

The purpose of this retrospective study was to compare the hip structural analysis (HSA) levels of patients with those of a hip fracture group. All patients with an initial hip fracture who were older than or equal to 65 years old and admitted to our hospital between March 2018 and January 2019 were eligible for this study. During the study period, 134 hip fracture patients aged 65 years and older were admitted to the study institution, and a total of 51 hip fracture patients were ultimately assigned to the patient group. Age, sex, body mass index (BMI), skeletal muscle index (SMI), and vitamin D were matched in the two groups (hip fracture (HF) group vs. non-hip fracture group) using propensity score matching (PSM) without any statistical differences. Following propensity score matching, 51 patients in the HF group and 51 patients in the non-HF group were included in the study, respectively. Hip axis length (p = 0.031), neck-shaft angle (p = 0.043), width of intertrochanter (p = 0.005), and femur shaft (p = 0.01) were found to be significantly higher in the HF group (107.31 (mean) ± 9.55 (standard deviation, SD), 131.11 ± 5.29, 5.57 ± 0.58, and 3.05 ± 0.23, respectively) than in the non-HF group (102.07 ± 14.15, 128.85 ± 5.81, 5.29 ± 0.38, and 2.92 ± 0.23, respectively). However, cross-sectional area (CSA) of femur neck (p = 0.005) and femur shaft (p = 0.01) as well as cortical thickness (CT) of femur neck (p = 0.031) and femur shaft (p = 0.031) were found to be significantly lower in the HF group (1.93 ± 0.44, 3.18 ± 0.83, 0.11 ± 0.02, and 0.38 ± 0.09, respectively) than in the non-HF group (2.12 ± 0.46, 3.57 ± 0.78, 0.13 ± 0.03, and 0.47 ± 0.11, respectively). The HSA showed excellent sensitivity (82.4% to 90.2%). HSA is an important factor in predicting the occurrence of hip fracture. Therefore, not only should bone mineral density (BMD) be considered clinically, but it is also important to look closely at HSA for risk of hip fracture.

New Insights Into Monogenic Causes of Osteoporosis

Osteoporosis, characterized by deteriorated bone microarchitecture and low bone mineral density, is a chronic skeletal disease with high worldwide prevalence. Osteoporosis related to aging is the most common form and causes significant morbidity and mortality. Rare, monogenic forms of osteoporosis have their onset usually in childhood or young adulthood and have specific phenotypic features and clinical course depending on the underlying cause. The most common form is osteogenesis imperfecta linked to mutations in COL1A1 and COL1A2, the two genes encoding type I collagen. However, in the past years, remarkable advancements in bone research have expanded our understanding of the intricacies behind bone metabolism and identified novel molecular mechanisms contributing to skeletal health and disease. Especially high-throughput sequencing techniques have made family-based studies an efficient way to identify single genes causative of rare monogenic forms of osteoporosis and these have yielded several novel genes that encode proteins partaking in type I collagen modification or regulating bone cell function directly. New forms of monogenic osteoporosis, such as autosomal dominant osteoporosis caused by WNT1 mutations or X-linked osteoporosis due to PLS3 mutations, have revealed previously unidentified bone-regulating proteins and clarified specific roles of bone cells, expanded our understanding of possible inheritance mechanisms and paces of disease progression, and highlighted the potential of monogenic bone diseases to extend beyond the skeletal tissue. The novel gene discoveries have introduced new challenges to the classification and diagnosis of monogenic osteoporosis, but also provided promising new molecular targets for development of pharmacotherapies. In this article we give an overview of the recent discoveries in the area of monogenic forms of osteoporosis, describing the key cellular mechanisms leading to skeletal fragility, the major recent research findings and the essential challenges and avenues in future diagnostics and treatments.

Does bone mineral density improve the predictive accuracy of fracture risk assessment? A prospective cohort study in Northern Denmark

OBJECTIVE

To evaluate the added predictive accuracy of bone mineral density (BMD) to fracture risk assessment.

DESIGN

Prospective cohort study using data between 01 January 2010 and 31 December 2012.

SETTING

North Denmark Osteoporosis Clinic of referred patients presenting with at least one fracture risk factor to the referring doctor.

PARTICIPANTS

Patients aged 40-90 years; had BMD T-score recorded at the hip and not taking osteoporotic preventing drugs for more than 1 year prior to baseline.

MAIN OUTCOME MEASURES

Incident diagnoses of osteoporotic fractures (hip, spine, forearm, humerus and pelvis) were identified using the National Patient Registry of Denmark during 01 January 2012-01 January 2014. Cox regression was used to develop a fracture model based on predictors in the Fracture Risk Assessment Tool (FRAX®), with and without, binary and continuous BMD. Change in Harrell's C-Index and Reclassification tables were used to describe the added statistical value of BMD.

RESULTS

Adjusting for predictors included in FRAX®, patients with osteoporosis (T-score ≤-2.5) had 75% higher hazard of a fracture compared with patients with higher BMD (HR: 1.75 (95% CI 1.28 to 2.38)). Forty per cent lower hazard was found per unit increase in continuous BMD T-score (HR: 0.60 (95% CI 0.52 to 0.69)).Accuracy improved marginally, and Harrell's C-Index increased by 1.2% when adding continuous BMD (0.76 to 0.77). Reclassification tables showed continuous BMD shifted 529 patients into different risk categories; 292 of these were reclassified correctly (57%; 95% CI 55% to 64%). Adding binary BMD however no improvement: Harrell's C-Index decreased by 0.6%.

CONCLUSIONS

Continuous BMD marginally improves fracture risk assessment. Importantly, this was only found when using continuous BMD measurement for osteoporosis. It is suggested that future focus should be on evaluation of this risk factor using routinely collected data and on the development of more clinically relevant methodology to assess the added value of a new risk factor.