Quantitative ultrasound or clinical risk factors--which best identifies women at risk of osteoporosis?

Heel Ultrasound Scan in Detecting Osteoporosis in Low Trauma Fracture Patients

Osteoporosis is the most common metabolic disease with significant impact on the morbidity and mortality of affected patients. Osteoporosis has a significant impact on the economy worldwide. The aim of this study was to find out whether heel ultrasound is as good as central bone densitometry scanning in diagnosing osteoporosis in patients who are at high risk of osteoporosis. This was a prospective study of patients comparing heel ultrasound to central bone densitometry scanning (dual X-ray absorptiometry, DEXA) in patients. The recruited patients attended for a DEXA scan of the left hip and lumbar spine. All subjects had an ultrasound of the left heel using the quantitative heel ultrasound machine. The results of DEXA scan were blinded from the results of ultrasound and vice versa. There were 59 patients who took part in the study, 12 men and 47 women. The mean age was 66 years (SD 11.9) and mean weight was 62.5 kg (SD 10.7). The sensitivity and specificity of the ultrasound heel test to predict osteoporosis were 53% (95%CI: 29-77) and 86% (95%CI: 75-96) respectively. Specificity for predicting bone mineral density (BMD)-defined osteoporosis was high (86%), but sensitivity was low (53%). A heel ultrasound result in the osteoporotic range was highly predictive of BMD-defined osteoporosis. A positive ultrasound heel test in high risk patients is more useful in ruling in osteoporosis than a negative test to rule out osteoporosis.

Does low bone density influence symptoms and functional status in patients with fibromyalgia? Observations from rural South India

INTRODUCTION

The presence of more than one musculoskeletal disease has been found to impair quality of life (QoL). The influence of low bone mineral density (BMD) on symptoms and function in those with fibromyalgia syndrome (FMS) is unknown.

METHODOLOGY

A cross sectional study was carried out on 158 patients attending camps in rural South India. BMD was determined using quantitative ultrasound of the distal radius. Symptoms and function were assessed using a visual analogue scale (VAS) and the Fibromyalgia Impact Questionnaire (FIQ).

RESULTS

Low BMD was seen in 81.6% (129/158) of the persons screened. FMS was seen in 37/158 persons, of which 31/37 (83.7%) had low BMD.

CONCLUSION

FMS with low bone density leads to higher levels of pain and a poorer QoL compared to those without FMS. Coexisting musculoskeletal problems could also contribute to this. Therefore, medical practitioners and rehabilitation specialists should consider screening for bone density among those with FMS and should use this information to decide appropriate therapies to reduce pain and improve QoL.

Discriminative ability of heel quantitative ultrasound in postmenopausal women with prevalent low-trauma fractures: application of optimal threshold cutoff values using CART models

Quantitative ultrasound (QUS) of the heel has been proposed as a screening tool to evaluate the bone status and risk of osteoporotic fragility fractures. The aim of this study was to define threshold values of QUS that would maximize the predictive ability of this technique to discriminate subjects with fragility fractures. A cross-sectional analysis was made of a cohort of 1132 postmenopausal women with a mean age of 58 yr. A total of 361 women (31.9%) presented with a history of osteoporotic fracture. Most fractures (74.1%) were nonvertebral. For all patients, a questionnaire of osteoporosis risk factors and measurements of the heel QUS and bone mineral density at the lumbar spine and the proximal femur obtained by dual-energy X-ray absorptiometry (DXA) were assessed. Spinal radiographs were assessed for fractures and historical nonvertebral fragility fractures. Sensitivity, specificity, predictive values, likelihood ratios, and receiver operator characteristic (ROC) curve QUS values were calculated using the optimal threshold identified in the classification and regression trees (CART) models. Cutoff values calculated from the best CART model (i.e., a quantitative ultrasound index (QUI) greater than 88.5% in women aged 58 yr or older) yielded 88.8% (95% confidence interval [CI]: 81.4-93.5) for sensitivity, a negative predictive value of 93.8 (95% CI: 89.4-96.4), and 70.4% (95% CI: 64.6-75.7) for specificity. This cutoff value would obviate the need to perform DXA in 43.1% of the population. The area under the ROC curve of the best model was 0.8363 (95% CI: 0.8249-0.8477). In conclusion, QUS was shown to discriminate between women with and without a history of fragility fracture and constitutes a useful tool for assessing fracture risk. The application of decision trees (CART analyses) was helpful to define the optimal threshold QUS values.

α-Actinin-3 deficiency is associated with reduced bone mass in human and mouse

Bone mineral density (BMD) is a complex trait that is the single best predictor of the risk of osteoporotic fractures. Candidate gene and genome-wide association studies have identified genetic variations in approximately 30 genetic loci associated with BMD variation in humans. α-Actinin-3 (ACTN3) is highly expressed in fast skeletal muscle fibres. There is a common null-polymorphism R577X in human ACTN3 that results in complete deficiency of the α-actinin-3 protein in approximately 20% of Eurasians. Absence of α-actinin-3 does not cause any disease phenotypes in muscle because of compensation by α-actinin-2. However, α-actinin-3 deficiency has been shown to be detrimental to athletic sprint/power performance. In this report we reveal additional functions for α-actinin-3 in bone. α-Actinin-3 but not α-actinin-2 is expressed in osteoblasts. The Actn3(-/-) mouse displays significantly reduced bone mass, with reduced cortical bone volume (-14%) and trabecular number (-61%) seen by microCT. Dynamic histomorphometry indicated this was due to a reduction in bone formation. In a cohort of postmenopausal Australian women, ACTN3 577XX genotype was associated with lower BMD in an additive genetic model, with the R577X genotype contributing 1.1% of the variance in BMD. Microarray analysis of cultured osteoprogenitors from Actn3(-/-) mice showed alterations in expression of several genes regulating bone mass and osteoblast/osteoclast activity, including Enpp1, Opg and Wnt7b. Our studies suggest that ACTN3 likely contributes to the regulation of bone mass through alterations in bone turnover. Given the high frequency of R577X in the general population, the potential role of ACTN3 R577X as a factor influencing variations in BMD in elderly humans warrants further study.

Bone morphogenetic protein-2 activity is regulated by secreted phosphoprotein-24 kd, an extracellular pseudoreceptor, the gene for which maps to a region of the human genome important for bone quality

The material properties of bone are the sum of the complex and interrelated anabolic and catabolic processes that modulate formation and turnover. The 2q33-37 region of the human genome contains quantitative trait loci important in determining the broadband ultrasound attenuation (an index of trabecular microarchitecture, bone elasticity, and susceptibility to fracture) of the calcaneus, but no genes of significance to bone metabolism have been identified in this domain. Secreted phosphoprotein-24 kd (SPP24 or SPP2) is a novel and relatively poorly characterized growth hormone-regulated gene that maps to 2q37. The purpose of this review is to summarize the status of research related to spp24 and how it regulates bone morphogenetic protein (BMP) bioactivity in bone. SPP24 codes for an extracellular matrix protein that contains a high-affinity BMP-2-binding transforming growth factor-beta receptor II homology 1 loop similar to those identified in fetuin and the receptor itself. SPP24 is transcribed primarily in the liver and bone. High levels of spp24 (a hydroxyapatite-binding protein) are found in bone, and small amounts are found in fetuin-mineral complexes. Full-length secretory spp24 inhibits ectopic bone formation, and overexpression of spp24 reduces murine bone mass and density. Spp24 is extremely labile to proteolysis, a process that regulates its bioactivity in vivo. For example, an 18.5-kd degradation product of spp24, designated spp18.5, is pro-osteogenic. A synthetic cyclized Cys(1)-to-Cys(19) disulfide-bonded peptide (BMP binding peptide) corresponding to the transforming growth factor-beta receptor II homology 1 domain of spp24 and spp18.5 binds BMP-2 and increases the rate and magnitude of BMP-2-mediated ectopic bone formation. Thus, the mechanism of action of spp18.5 and spp24 may be to regulate the local bioavailability of BMP cytokines. SPP24 is regulated by growth hormone and 3 major families of transcription factors (nuclear factor of activated T cells, CCAAT/enhancer-binding protein, Cut/Cux/CCAAT displacement protein) that regulate mesenchymal cell proliferation, embryonic patterning, and terminal differentiation. The gene contains at least 2 single nucleotide polymorphisms. Given its mechanism of action and sequence variability, SPP24 may be an interesting candidate for future studies of the genetic regulation of bone mass, particularly during periods of BMP-mediated endochondral bone growth, development, and fracture healing.

Does quantitative tibial ultrasound predict low bone mineral density defined by dual energy X-ray absorptiometry?

PURPOSE

Efforts for the early detection of bone loss and subsequent fracture risk by quantitative ultrasound (QUS), which is a non-invasive, radiation free, and cheaper method, seem rational to reduce the management costs. We aimed in this study to assess the probable correlation of speed of sound (SOS) values obtained by QUS with bone mineral density (BMD) as measured by the gold standard method, dual energy X-ray absorptiometry (DEXA), and to investigate the diagnostic value of QUS to define low BMD.

MATERIALS AND METHODS

One hundred twenty-two postmenopausal women having prior standard DEXA measurements were included in the study. Spine and proximal femur (neck, trochanter and Ward's triangle) BMD were assessed in a standard protocol by DEXA. The middle point of the right tibia was chosen for SOS measurement by tibial QUS.

RESULTS

The SOS values were observed to be significantly higher in the normal BMD (t score > -1) group at all measurement sites except for the lumbar region, when compared with the low BMD group (t score < -1). SOS was negatively correlated with age (r= -0.66) and month since menopause (r= -0.57). The sensitivity, specificity, and positive and negative predictive values for QUS t score to diagnose low BMD did not seem to be satisfactory at either of the measurement sites.

CONCLUSION

Tibial SOS was correlated weakly with BMD values of femur and lumbar spine as measured by DEXA and its diagnostic value did not seem to be high for discriminating between normal and low BMD, at these sites.

Cost-Effectiveness Analysis of Various Screening Methods for Osteoporosis in Perimenopausal Thai Women

OBJECTIVE

To perform a health economics analysis of 5 screening programs for osteoporosis in perimenopausal Thai women comparing two alternatives; without intervention and universal treatment without screening.

DESIGN

A decision analysis was performed to evaluate five screening strategies: Dual energy X-ray absorptiometry (DXA), Quantitative ultrasound sonography (QUS), risk index (clinical risk factors), two-step screening with QUS followed by DXA, and screening with risk index followed by DXA, comparing outcomes without intervention and universal treatment without screening.

RESULTS

The costs for universal treatment, screening by DXA with treatment, screening by QUS with treatment, screening by Risk index with treatment, screening by QUS and DXA with treatment, and screening by Risk index and DXA with treatment strategies to prevent one fracture were 207.82, 88.42, 147.05, 127.67, 71.33, and 60.30 USD, respectively. The cost for no intervention to prevent one fracture is 8.49 USD (1 USD = 40 Thai baht).

CONCLUSION

At present, no intervention is the most cost effective strategy. However, screening with risk index and DXA with treatment became the most cost effective when the patients reached the postmenopausal period and had a high risk index, for which the prevalence of osteoporosis will increase. Cost effective screening guidelines still cannot be explicitly established until further data addressing the association between bone mass measurements in the hip and hip fracture risk, are available.

Comparison of questionnaire and quantitative ultrasound techniques as screening tools for DXA

The aim of the study is to assess the sensitivity and specificity of different techniques and their ability to act as screening tools in relation to dual energy X-ray absorptiometry (DXA) in a group of 208 postmenopausal women. In this study we examined eight screening systems for the diagnosis of osteoporosis, the osteoporosis self-assessment tool (OST), the osteoporosis risk assessment instrument (ORAI), the osteoporosis index of risk (OSIRIS), a risk index derived using data from the study of osteoporotic fractures (SOFSURF), the simple calculated osteoporosis risk estimation (SCORE), patient body weight (pBW), along with two ultrasound based systems, the Sunlight Omnisense (Sunlight Medical, Rehovot, Israel) and the CUBA Clinical (McCue plc, Winchester, UK). The sensitivity and specificity of the different techniques in relation to DXA were plotted as receiver-operating characteristic (ROC) curves at three different levels (DXA T-score -2.5 osteoporosis, -2 and -1 osteopenia). The areas under the curves (AUC) were calculated and showed broadband ultrasound attenuation (BUA) at the calcaneus to provide consistently the highest AUC (0.77-0.81). The velocity of sound (VOS) of the calcaneus (AUC=0.72-0.76) was equally good, but was out-performed by some of the questionnaire systems (AUC=0.66-0.79). Both the questionnaire systems and the CUBA Clinical out-perform the Sunlight Omnisense (AUC=0.58-0.7), which showed comparable performance with body weight (AUC=0.66-0.69). The results show that QUS is capable of selecting patients with low bone density as measured by DXA. A patient displaying a low QUS value should be followed up with a DXA scan to confirm the diagnosis.

The ability of peripheral quantitative ultrasound to identify patients with low bone mineral density in the hip or spine

This study aims to assess the sensitivity and specificity of two commercially available quantitative ultrasound (QUS) scanners (CUBA Clinical, Sunlight Omnisense), to differentiate patients with osteoporosis (OP) or osteopenia at the spine and hip confirmed by dual-energy x-ray absorptiometry (DXA) and to investigate the optimum cut-off values to maximize the effectiveness of the screening technique. Participants (n = 268) received DXA scans on their lumbar spine (L1-L4) and hip, with paired QUS scans on their distal radius, proximal phalanx, midshaft tibia and calcaneus. Scanners were evaluated by using receiver-operating characteristics curves and their area under the curve (AUC) values. Measurement of the calcaneus by the CUBA Clinical showed a superior ability to predict DXA, with AUC values between 0.75 to 0.83 in comparison with AUC values of 0.60 to 0.70 for the Sunlight Omnisense. Cut-off values varied according to the technique used and the accuracy of the screening required. Assessment of the calcaneus was the best QUS technique for the prediction of low bone density at the axial skeleton as diagnosed by DXA.

The relationship between social deprivation, osteoporosis, and falls

The aim of this study was to assess the relationship between heel BMD, risk factors for osteoporosis, falls history, and the Jarman Underprivileged Area Score in an older community population. From the general practice register, 1,187 women (mean age 70, range 60 to 94) were recruited. BMD of the heel was measured using the GE Lunar PIXI densitometer. A T-score cutoff for predicted osteoporosis at the spine or hip of -1.7 was used. A risk factor questionnaire was completed that included fracture history and falls history. The odds ratio (OR) with a 95% confidence interval (CI) was calculated for each risk factor for each quartile of Jarman score and for the diagnosis of osteoporosis. Logistic regression was used to identify the risk factors that predict lone bone mass in the heel. There were no significant differences between women in different quartiles of Jarman score in terms of age and body mass index (BMI). Women in the highest two quartiles of Jarman score (i.e., most deprived) had a significantly higher likelihood of osteoporosis (OR=1.82; 95% CI, 1.03 to 1.63; and OR=1.85; 95% CI, 1.04 to 1.64, respectively) and significantly lower BMD ( p=0.008). Women in these two quartiles were significantly more likely to have had a history of previous fracture (OR=1.66; 95% CI, 1.01 to 1.53), but there was no difference in falls history. Women in the lowest quartile (least deprived) were also significantly less likely to smoke ( p=0.011) but were not significantly different in terms of other risk factors (e.g., dietary calcium and activity). BMI, age, kyphosis, significant visual problems, and quartile of Jarman score were significant risk factors for low bone mass. Risk factors identified those with low bone mass at the heel with a sensitivity and specificity of 72%. In conclusion, women in the lowest quartile of Jarman score (i.e., least deprived) have significantly higher heel BMD compared with the rest of the population.

Evaluation of calcaneus bone densitometry against hip and spine for diagnosis of osteoporosis

Dual X-ray absorptiometry (DXA) is now widely available as a method for assessing bone density. However, the place of peripheral bone densitometry in clinical practice for diagnosis of osteoporosis is not yet clear. To examine the potential use in our district general hospital setting, we compared calcaneus measurements with conventional DXA of the hip and spine in 100 patients referred for assessment following identification of risk factors for osteoporosis. Measurements were made on both heels and the results were found to be similar but not completely interchangeable. Use of receiver operating characteristic curves confirmed that a threshold T-score of -1.6 could be used to identify many of the high risk subjects. However, there was only moderate agreement between fracture risk classifications derived from heel T-scores, and diagnostic classification (osteoporosis/osteopenia/normal) derived from axial DXA. The specificity of heel measurements was high, but sensitivity was poorer. Heel measurements could therefore be valuable in some circumstances for finding patients for whom treatment of osteoporosis would be appropriate, such as in a population with a low prevalence of osteoporosis. They may also be of value in a population with a high prevalence of disease, particularly if there were no alternative means of bone densitometry. However, with an intermediate prevalence, the relatively high risk of false negative values would mean that false reassurance could be given to many of those classed as "low risk". This could be a major drawback in clinical practice if heel densitometry were used as the initial investigation and axial measurements were also available, since they would give conflicting results for a substantial proportion of these patients.

Further validation of a questionnaire to identify women likely to have low bone density

A questionnaire instrument called the Simple Calculated Osteoporosis Risk Estimation (SCORE*) stratifies risk for osteoporosis, potentially reducing population-screening costs. SCORE is calculated using race, weight, age, history of estrogen use, fracture history, and presence/absence of rheumatoid arthritis. We tested SCORE in 912 postmenopausal women aged 45 yr or more using a Hologic QDR4500C densitometer for the total hip, femoral neck, and lumbar spine. National Health and Nutrition Examination Survey (NHANES III) norms were used to calculate hip T-scores. Low bone density (T-score < -2.0) was found in 29.6% of patients at the femoral neck, 17.7% at the total hip, 36.1% at the lumbar spine, and 46.1% at one or more sites. The sensitivity/specificity of the SCORE model (using a threshold of 6 points) was 0.97/0.36 for the femoral neck, 0.95/0.30 for the total hip, 0.86/0.35 for the spine, and 0.88/0.41 for any site (total hip, femoral neck, or spine). When used to detect low bone density at any site, SCORE would have deferred 27.6% of women referred for DXA scans, but 20.7% of these (5.7% of the entire population) would have been false-negatives, and thus inappropriately deferred. At a cutpoint of 3 instead of 6, sensitivity/specificity was 0.96/0.16. In those aged 50-60, the group with the greatest need for risk stratification, sensitivity/specificity for low density at any site was 0.72/0.54, and 46.1% would have been deferred, but 18.5% of this group would have been false-negatives. A cutpoint of 1 in this age group yielded sensitivity/specificity of 0.94/0.16. After age 65, few women would be deferred.

CONCLUSION

When used to detect low bone density at any site with sufficient sensitivity for clinical practice, SCORE did not have sufficient discriminatory power to be broadly applicable.

The use of ultrasound in the assessment of bone status

The assessment of skeletal status has wide clinical applications, especially in the management of osteoporosis. Osteoporosis, once thought of as an unpreventable and untreatable aging process, has revealed many of its secrets over the last decade, and the advent of successful drug therapy has changed our perception of the disease. Non-invasive techniques play a fundamental role in the diagnosis of osteoporosis and in the assessment of the efficacy of drug treatments. The primary technique used in osteoporosis is dual X-ray absorptiometry (DXA), that has been established as a reliable means of measuring bone density. Quantitative ultrasound (QUS), because of the relative portability of the equipment, ease of use, lack of ionizing radiation and low cost, has great potential for widespread use. Five devices for QUS assessment have recently been approved by the Food and Drug Administration and many more applications are in progress. QUS is a relatively new technology, at least in its application to bone fragility. Nevertheless, QUS has demonstrated that it is able to detect bone fragility as well as DXA. However, diagnosis of osteoporosis by QUS remains contentious, but the problems are due more to the limitations of the present T-scores rather than to the technique. A better option for QUS would be to report results in terms of remaining lifetime fracture risk, keeping in mind that a risk estimate needs not only the QUS or DXA measurement, but also the specific data, such as age, weight, gender, hormonal status and fracture history of the patient.