Prospective identification of postmenopausal osteoporotic women at high vertebral fracture risk by radiography, bone densitometry, quantitative ultrasound, and laboratory findings: results from the PIOS study

Current and Emerging Diagnostic Imaging-Based Techniques for Assessment of Osteoporosis and Fracture Risk

Osteoporosis is a metabolic bone disorder characterized by low bone mass, degradation of bone microarchitecture, and susceptibility to fracture. It is a growing major health concern across the world, especially in the elderly population. Osteoporosis can cause hip or spinal fractures that may lead to high morbidity and socio-economic burden. Therefore, there is a need for early diagnosis of osteoporosis and prediction of fragility fracture risk. In this review, state of the art and recent advances in imaging techniques for diagnosis of osteoporosis and fracture risk assessment have been explored. Segmentation methods used to segment the regions of interest and texture analysis methods used for classification of healthy and osteoporotic subjects are also presented. Furthermore, challenges posed by the current diagnostic tools have been studied and feasible solutions to circumvent the limitations are discussed. Early diagnosis of osteoporosis and prediction of fracture risk require the development of highly precise and accurate low-cost diagnostic techniques that would help the elderly population in low economies.

Epidemiology of Vertebral Fractures

Vertebral fractures are one of the most common fractures associated with skeletal fragility and can cause as much morbidity as hip fractures. However, the epidemiology of vertebral fractures differs from that of osteoporotic fractures at other skeletal sites in important ways, largely because only one quarter to one-third of vertebral fractures are recognized clinically at the time of their occurrence and otherwise require lateral spine imaging to be recognized. This article first reviews the prevalence and incidence of clinical and radiographic vertebral fractures in populations across the globe and secular trends in the incidence of vertebral fracture over time. Next, associations of vertebral fractures with measures of bone mineral density and bone microarchitecture are reviewed followed by associations of vertebral fracture with various textural measures of trabecular bone, including trabecular bone score. Finally, the article reviews clinical risk factors for vertebral fracture and the association of vertebral fractures with morbidity, mortality, and other subsequent adverse health outcomes.

Management of severe osteoporosis

INTRODUCTION

Severe osteoporosis represents a disease of high mortality and morbidity. Recognition of what constitutes and causes severe osteoporosis and aggressive intervention with pharmacological agents with evidence to reduce fracture risk are outlined in this review.

AREAS COVERED

This review is a blend of evidence obtained from literature searches from PubMed and The National Library of Medicine (USA), clinical experience and the author's opinions. The review covers the recognition of what constitutes severe osteoporosis, and provides up-to-date references on this sub-set of high risk patients.

EXPERT OPINION

Severe osteoporosis can be classified by using measurements of bone densitometry, identification of prevalent fractures, and, knowledge of what additional risk factors contribute to high fracture risk. Once recognized, the potential consequences of severe osteoporosis can be mitigated by appropriate selection of pharmacological therapies and modalities to reduce the risk for falling.

Influence of obesity on vertebral fracture prevalence and vitamin D status in postmenopausal women

Background

It is well established that weight is an important determinant of bone health. Whereas obesity is associated with increased mortality and morbidity from diabetes and cardiovascular diseases, high body weight is widely believed to be associated to hypovitaminosis D and protective against the development of osteoporosis and fracture risk. The objective of the study was to evaluate the effect of BMI on vitamin D status and on densitometric vertebral fractures (VFs) in a large series of asymptomatic women aged over 50 who had a VFA examination during their bone mineral density (BMD) testing.

Methods

We enrolled 429 postmenopausal women (mean age, weight and BMI of 59.5 ± 8.3 (50 to 83) years, 75.8 ± 13.3 (35 to 165) kgs and 29.9 ± 5.2 (14.6 to 50.8) kg/m², respectively. Lateral VFA images and scans of the lumbar spine and proximal femur were obtained using a Lunar Prodigy densitometer. VFs were defined using the Genant semiquantitative (SQ) approach. Clinical risk factors of osteoporosis were collected and 25-hydroxivitamin D was measured using electrochimiluminescence (Roche).

Results

Prevalence of osteoporosis and hypovitaminosis D (<20 ng/ml) was 21.0 % and 78.1 % respectively. VFs grade 2/3were identified in 76 (17.7 %). Comparison between women according to their BMI showed that obese women had a higher BMD and less proportion of women with osteoporosis and VFs grade 2/3 than lean and overweight women. The prevalence of VFs globally increased with age and as BMI and BMD declined. Stepwise regression analysis showed that the presence of osteoporosis was independently related to BMI and history of fractures while the presence of grade 2/3 VFs was independently related to age, hypovitaminosis D and years of menopause.

Conclusion

Obese women had a higher BMD and lower prevalence of VFs. VFs were significantly related to age, hypovitaminosis D and years since menopause. However, among obese women, prevalence of VFs was increased in osteoporotic women.

Dual-energy X-ray absorptiometry of human metatarsals: precision, least significant change and association to ex vivo fracture force

BACKGROUND

Fractures are common in foot bones, but clinicians lack adequate indices of bone strength.

OBJECTIVES

We used dual-energy X-ray absorptiometry (DXA) to measure bone mineral density (BMD) and content (BMC) of excised human metatarsals, determined intra- and inter-rater measurement precision, and assessed associations between BMD/BMC and ex vivo bone fracture strength.

METHODS

Two raters each made two measurements of whole-bone and sub-regional BMD and BMC in both second and third metatarsals from 10 cadavers. Variance components analysis was used to assess variability attributable to repeat measurements, raters, sub-regions, bones, sides, and cadavers. Root-mean-square standard deviation (RMS-SD) and least-significant change (LSC) were used to assess rater precision and ultimate forces during 3-point bending were tested for correlations with BMD and BMC.

RESULTS

Variation due to repeat measurements and rater was low (<1% combined) for BMD and BMC. RMS-SD for whole metatarsal BMD of both metatarsals ranged from 0.004 to 0.010 g/cm(2) and 0.062 to 0.086 g for BMC. Whole metatarsal and sub-region BMD and BMC were strongly correlated to ex vivo fracture force (r(2)=0.67-0.93).

CONCLUSIONS

DXA measurements of BMD and BMC have high intra- and inter-rater precision and are strongly correlated to ex vivo bone strength.

Systematic vertebral fracture assessment in asymptomatic postmenopausal women

INTRODUCTION

Recognition of vertebral fractures (VFs) changes the patient's diagnostic classification, estimation of fracture risk, and threshold for pharmacological intervention. Vertebral fracture assessment (VFA) enables the detection of VFs in the same session as bone mineral density (BMD) testing.

OBJECTIVE

To study prevalence and risk factors of VFs using VFA in asymptomatic women and measure its effect on treatment recommendations.

METHODS

We enrolled 908 postmenopausal women (mean age, weight and BMI of 60.9 ± 7.7 (50-91) years, 73.2 ± 13.2 (35-150) kg and 29.8 ± 5.3 (14.5-50.8) kg/m(2), respectively. Lateral VFA images and scans of the lumbar spine and proximal femur were obtained using a GE Healthcare Lunar Prodigy densitometer. VFs were defined using a combination of Genant semiquantitative (SQ) approach and morphometry.

RESULTS

VFs were identified in 382 patients (42.0%): 203 (22.3%) had grade 1 and 179 (19.7%) had grade 2 or 3. The prevalence of VFA-detected fractures globally increased significantly with age and as BMI and BMD declined. A fracture was identified on VFA in 63 (28.3%) women with normal BMD (8.5% had grade 2/3 VFs) and in 145 (38.5%) with osteopenia (15.7% had grade 2/3 VFs). Stepwise regression analysis showed that presence of VFs was independently related to age, BMI, number of parity, history of peripheral fracture and lumbar spine BMD.

CONCLUSION

A high proportion of women with asymptomatic VFs would not receive treatment if screening were based only on BMD evaluation. Our results support the recommendation to enlarge the indications of VFA in the presence of risk factors such as age over 60, multiparity, history of peripheral traumatic fractures and low BMI.

Vertebral fracture assessment in asymptomatic men and its impact on management

INTRODUCTION

Recognition of vertebral fractures (VFs) change the patient's diagnostic classification, estimation of fracture risk, and threshold for pharmacological intervention. Vertebral fracture assessment (VFA) enables the detection of VFs in the same session as bone mineral density (BMD) testing.

OBJECTIVE

To study prevalence and risk factors of VFs using VFA in asymptomatic men and measure its impact on patients' management.

METHODS

We enrolled 791 men aged between 45 and 89 (mean age, weight and BMI of 62.4±8.6) (45 to 89) years, 74.9±12.7 (40 to 163) and 26.3±4.0 (16.6 to 43.8) kg/m(2), respectively. Lateral VFA images and scans of the lumbar spine and proximal femur were obtained using a GE Healthcare Lunar Prodigy densitometer. VFs were defined using a combination of Genant semiquantitative (SQ) approach and morphometry.

RESULTS

VFs were identified in 318 (40.3%): 206 (26.0%) had grade 1 and 112 (14.2%) had grade 2 or 3. As would be expected, the prevalence of VFA-detected fractures globally increased significantly with age and as BMI and BMD declined. A fracture was identified on VFA in 85 (32.4%) of men with normal BMD (6.9% had grade 2/3 VFs) and in 144 (35.8%) with osteopenia (11.7% had grade 2/3 VFs). Stepwise regression analysis showed that presence of VFs was independently related to the osteoporotic status (OR=4.761, 95%CI [2.956-7.668]; p<0.0001) and current smoking (OR=1.717, 95%CI [1.268-2.323]; p=0.002).

CONCLUSION

Our results support the recommendation to enlarge the indications of VFA to all the men referred for DXA measurement.

Quantitative ultrasound of the heel and fracture risk assessment: an updated meta-analysis

Meta-analysis of prospective studies shows that quantitative ultrasound of the heel using validated devices predicts risk of different types of fracture with similar performance across different devices and in elderly men and women. These predictions are independent of the risk estimates from hip DXA measures.

INTRODUCTION

Clinical utilisation of heel quantitative ultrasound (QUS) depends on its power to predict clinical fractures. This is particularly important in settings that have no access to DXA-derived bone density measurements. We aimed to assess the predictive power of heel QUS for fractures using a meta-analysis approach.

METHODS

We conducted an inverse variance random effects meta-analysis of prospective studies with heel QUS measures at baseline and fracture outcomes in their follow-up. Relative risks (RR) per standard deviation (SD) of different QUS parameters (broadband ultrasound attenuation [BUA], speed of sound [SOS], stiffness index [SI], and quantitative ultrasound index [QUI]) for various fracture outcomes (hip, vertebral, any clinical, any osteoporotic and major osteoporotic fractures) were reported based on study questions.

RESULTS

Twenty-one studies including 55,164 women and 13,742 men were included in the meta-analysis with a total follow-up of 279,124 person-years. All four QUS parameters were associated with risk of different fracture. For instance, RR of hip fracture for 1 SD decrease of BUA was 1.69 (95% CI 1.43-2.00), SOS was 1.96 (95% CI 1.64-2.34), SI was 2.26 (95%CI 1.71-2.99) and QUI was 1.99 (95% CI 1.49-2.67). There was marked heterogeneity among studies on hip and any clinical fractures but no evidence of publication bias amongst them. Validated devices from different manufacturers predicted fracture risks with similar performance (meta-regression p values > 0.05 for difference of devices). QUS measures predicted fracture with a similar performance in men and women. Meta-analysis of studies with QUS measures adjusted for hip BMD showed a significant and independent association with fracture risk (RR/SD for BUA = 1.34 [95%CI 1.22-1.49]).

CONCLUSIONS

This study confirms that heel QUS, using validated devices, predicts risk of different fracture outcomes in elderly men and women. Further research is needed for more widespread utilisation of the heel QUS in clinical settings across the world.

Quantitative ultrasound normative reference data for community-dwelling white and black females in the United States

Quantitative ultrasound (QUS) race-specific normative reference data are not available for accurate calculation of Z-scores. The primary aims of this study were (1) to develop a race-specific QUS reference database for white and black females and to compare estimated fracture risk between these 2 racial groups and (2) to compare stiffness index (SI) values of white females in this study to manufacturer-obtained values. Subjects included 1111 females (31% black), aged 20-85 yr (52 ± 19 yr), with a mean SI score of 93.7 ± 20.1. White females, aged 20-39 yr (n=213), were used to calculate T-scores, whereas Z-scores were age and race specific. Black females had significantly higher SI scores than white females (p<0.001). White females aged 50+ yr in this study had significantly higher SI scores compared with manufacturer-derived values. Results highlight the need for population- and race-specific normative data when using QUS as a screening tool for identifying high fracture risk.

Combining bone resorption markers and heel quantitative ultrasound to discriminate between fracture cases and controls

SUMMARY

This nested case-control analysis of a Swiss ambulatory cohort of elderly women assessed the discriminatory power of urinary markers of bone resorption and heel quantitative ultrasound for non-vertebral fractures. The tests all discriminated between cases and controls, but combining the two strategies yielded no additional relevant information.

INTRODUCTION

Data are limited regarding the combination of bone resorption markers and heel quantitative bone ultrasound (QUS) in the detection of women at risk for fracture.

METHODS

In a nested case-control analysis, we studied 368 women (mean age 76.2 +/- 3.2 years), 195 with low-trauma non-vertebral fractures and 173 without, matched for age, BMI, medical center, and follow-up duration, from a prospective study designed to predict fractures. Urinary total pyridinolines (PYD) and deoxypyridinolines (DPD) were measured by high performance liquid chromatography. All women underwent bone evaluations using Achilles+ and Sahara heel QUS.

RESULTS

Areas under the receiver operating-characteristic curve (AUC) for discriminative models of the fracture group, with 95% confidence intervals, were 0.62 (0.56-0.68) and 0.59 (0.53-0.65) for PYD and DPD, and 0.64 (0.58-0.69) and 0.65 (0.59-0.71) for Achilles+ and Sahara QUS, respectively. The combination of resorption markers and QUS added no significant discriminatory information to either measurement alone with an AUC of 0.66 (0.60-0.71) for Achilles+ with PYD and 0.68 (0.62-0.73) for Sahara with PYD.

CONCLUSIONS

Urinary bone resorption markers and QUS are equally discriminatory between non-vertebral fracture patients and controls. However, the combination of bone resorption markers and QUS is not better than either test used alone.

Quantitative ultrasound of the calcaneus in greek women: normative data are different from the manufacturer's normal range

Quantitative ultrasound (QUS) is considered a useful method in evaluating bone status. The aim of the present study was to establish the reference data for the QUS measurements of the calcaneus in a Greek population. We measured a QUS parameter, stiffness index (SI), at the right calcaneus in 1500 women using the Achilles express Ultrasonometer (GE Lunar, Madison, WI). Participants were divided into 7 groups according to their age with a 10-yr span in each group. A progressive decline was found in the SI values after the age of 39 yr in the current study. When the SI values were compared between the age groups, high statistically significant differences were obvious, especially between 20-29 and 50- to 59-yr age groups and 60-69 and 70- to 79-yr age groups (p < 0.0005). Additionally, in the Greek normal range (GNR), the SI values of those aged 60-69 and 70-79 yr were significantly higher (81.84+/-16.14 and 77.45+/-17.65, respectively) than those in the manufacturer's normal range (MNR; 75.84+/-16.14 and 69.10+/-17.65, p < 0.005, respectively). Using the manufacturer's values, significantly fewer women were classified as normal (48% vs 67.3%), although those with T-score < or =-2.5 were more (15.7%) compared with our Greek value (1.5%), and classification of subjects into risk-of-fracture categories was significantly different (kappa: 0.459, 66.2%, p < 0.0005). Multiple regression analysis showed that weight was the most significant predictor for SI in the age groups 30-39 (beta = 0.280, p < 0.05), 40-49, 60-69, and 70-79 yr (beta = 0.185, p < 0.005; beta = 0.329, p < 0.0005; beta = 0.494, p<0.0005, respectively). Using conventional categories of risk, we report a different classification of our subjects from those proposed by the manufacturer, supporting the concept that data specific to the Greek population are necessary.

Quantitative ultrasound in the management of osteoporosis: the 2007 ISCD Official Positions

Dual-energy X-ray absorptiometry (DXA) is commonly used in the care of patients for diagnostic classification of osteoporosis, low bone mass (osteopenia), or normal bone density; assessment of fracture risk; and monitoring changes in bone density over time. The development of other technologies for the evaluation of skeletal health has been associated with uncertainties regarding their applications in clinical practice. Quantitative ultrasound (QUS), a technology for measuring properties of bone at peripheral skeletal sites, is more portable and less expensive than DXA, without the use of ionizing radiation. The proliferation of QUS devices that are technologically diverse, measuring and reporting variable bone parameters in different ways, examining different skeletal sites, and having differing levels of validating data for association with DXA-measured bone density and fracture risk, has created many challenges in applying QUS for use in clinical practice. The International Society for Clinical Densitometry (ISCD) 2007 Position Development Conference (PDC) addressed clinical applications of QUS for fracture risk assessment, diagnosis of osteoporosis, treatment initiation, monitoring of treatment, and quality assurance/quality control. The ISCD Official Positions on QUS resulting from this PDC, the rationale for their establishment, and recommendations for further study are presented here.

Vertebral fracture assessment in healthy men: prevalence and risk factors

INTRODUCTION

Vertebral fracture assessment (VFA) is a technology that can reliably and accurately diagnose vertebral fractures with greater patient convenience, less radiation exposure, and lower cost than standard spine radiography.

OBJECTIVE

To study prevalence and risk factors of vertebral fractures using VFA in healthy men.

METHODS

The study cohort consists of a population of 216 healthy men aged between 50 and 79 (mean age, weight and BMI of 63.8 years, 73.3 kg and 25.7 kg/m2, respectively). Lateral VFA images and scans of the lumbar spine and proximal femur were obtained by two technologists using a GE Healthcare Lunar Prodigy densitometer. Vertebral fractures were defined using a combination of Genant semiquantitative (SQ) approach and morphometry.

RESULTS

Ninety-three percent of vertebrae from T4-L4 and 98% from T8-L4 were adequately visualized on VFA. Vertebral fractures were detected in 29.6% (64/216) of these men: 34/216 (15.7%) had grade 1 and 30/216 (13.8%) had grades 2 or 3. Twenty one of men with VFA-identified fracture (32.8%) had only a single vertebral fracture, while the other 67.2% had two or more. Fractures were most common in the mid-thoracic spine and at the thoraco-lumbar junction. As would be expected, the prevalence of VFA-detected fractures increased with age and as BMD declined. This group of men had a statistically significant lower weight, height, calcium consumption and T-score than those without a VFA-identified vertebral fracture. Regression analysis showed that presence of vertebral fracture was mainly related to the osteoporotic status (OR: 9.0; 95% CI: 3.5-22.8).

CONCLUSION

VFA allows evaluation of the majority of vertebral bodies in men. Vertebral fractures are common in healthy men and are related to low BMD.

The clinical use of quantitative ultrasound (QUS) in the detection and management of osteoporosis

For the detection and management of osteoporosis and osteoporosis-related fractures, quantitative ultrasound (QUS) is emerging as a relatively low-cost and readily accessible alternative to dual-energy X-ray absorptiometry (DXA) measurement of bone mineral density (BMD) in certain circumstances. The following is a brief, but thorough review of the existing literature with respect to the use of QUS in 6 settings: 1) assessing fragility fracture risk; 2) diagnosing osteoporosis; 3) initiating osteoporosis treatment; 4) monitoring osteoporosis treatment; 5) osteoporosis case finding; and 6) quality assurance and control. Many QUS devices exist that are quite different with respect to the parameters they measure and the strength of empirical evidence supporting their use. In general, heel QUS appears to be most tested and most effective. Overall, some, but not all, heel QUS devices are effective assessing fracture risk in some, but not all, populations, the evidence being strongest for Caucasian females over 55 years old. Otherwise, the evidence is fair with respect to certain devices allowing for the accurate diagnosis of likelihood of osteoporosis, and generally fair to poor in terms of QUS use when initiating or monitoring osteoporosis treatment. A reasonable protocol is proposed herein for case-finding purposes, which relies on a combined assessment of clinical risk factors (CR.F) and heel QUS. Finally, several recommendations are made for quality assurance and control.

Quantitative bone ultrasound at phalanges and calcaneus in osteoporotic postmenopausal women: influence of age and measurement site

Phalangeal and calcaneal quantitative ultrasound (QUS) measurements were tested in a postmenopausal osteoporotic population of a wide age range to assess their ability to identify subjects with vertebral fractures in a population of postmenopausal women with osteoporosis. A group of 127 osteoporotic women aged from 50 to 85 y, who had been postmenopausal for at least 5 y, were enrolled. All subjects underwent phalangeal and calcaneal QUS measurements, femoral neck and lumbar spine dual energy X-ray absorptiometry (DXA) measurements and lateral thoracic and lumbar spine radiography. Osteoporosis was defined on the basis of femoral neck or lumbar spine bone mineral density (BMD) T-score lower than -2.5 SD or of the presence of one or more vertebral atraumatic fractures, independently of BMD values. Fifty-two women had one or more vertebral fractures, while the remaining 75 had no evidence of previous fracture. Both QUS techniques were able to discriminate between fractured and nonfractured subjects in the whole group (p < 0.05). When patients aged <70 y (n = 43) and patients aged > or = 70 y (n = 84) were considered separately, phalangeal QUS and lumbar spine BMD were able to discriminate vertebral fractures in the younger group (p < 0.05), whereas calcaneal QUS was able to discriminate vertebral fractures in the older one (p < 0.05). The results of this study raise an issue of the optimal use of different QUS techniques and different skeletal sites in the management of osteoporosis in early or late postmenopausal life.

Quantitative Ultrasound--it is time to focus research efforts

Quantitative Ultrasound (QUS) methods show great potential for refined assessment of bone strength. However, for widespread clinical acceptance, three issues have to be resolved: Will patients with low QUS readings benefit from approved osteoporosis medications? How can we ensure good quality of QUS measurements in daily clinical practice? How much added value does QUS bring to risk factor based case-finding strategies? When addressing these issues, differences among QUS approaches need to be recognized and vague and misleading terminology, e.g., regarding bone quality assessment, needs to be avoided. Innovations including assessment of material or micro-structural properties and direct QUS measurements at the proximal femur are likely to spark additional interest in pursuing QUS research.