Peripheral bone mass measurements: current and future perspectives on quantitative ultrasound and peripheral DXA

Is calcaneal stiffness more sensitive to physical activity than forearm bone mineral density? A population-based study of persons aged 20 - 79 years

Aims: The aim of this study was to investigate the associations between forearm bone mineral density (BMD), calcaneal stiffness, and physical activity levels in a normal population using different non-invasive methods. Methods: The participants were invited to undergo bone measurements using single photon absorptiometry of the forearm and quantitative ultrasound (QUS) of the calcaneal bone, and also to complete a questionnaire. Physical activity levels were designated low, moderate, and high in the question on leisure-time activity. Results: There were 956 participants included in the present study. Forearm BMD in the eighth age decade was 0.40 g/cm2 (95% CI 0.33 - 0.46 g/cm2) lower than in the third decade among women and 0.28 g/cm2 (95% CI 0.18 - 0.37 g/cm2) lower among men. The differences in calcaneal stiffness between the same age decades were 22.4 (95% CI 17.5 - 27.4) among women and 15.8 (95% CI 8.0 - 23.5) among men. The correlation between forearm BMD and calcaneal stiffness was 0.58 (95% CI 0.52 - 0.64) in women and 0.34 (95% CI 0.25 - 0.42) in men. Reported moderate and high leisure-time activity levels in both genders were associated with higher calcaneal stiffness but not with forearm BMD. Conclusions: The QUS may be used to measure the effect of present physical activity levels on calcaneal bone at the population level. Further longitudinal studies are warranted in order to determine the most appropriate non-invasive method in population-based studies.

Association between alcohol consumption and bone strength in Korean adults: the Korean Genomic Rural Cohort Study

Previous studies have reported an inconsistent relationship between alcohol consumption and bone health. A growing body of research has shown that chronic alcoholism leads to osteopenia and increased incidence of skeletal fractures, but some studies have concluded that alcohol consumption may be associated with higher bone mineral density in elderly populations. However, most studies showing a significant relationship between alcohol consumption and bone status have been in Western countries; and subjects have usually been postmenopausal women. The purpose of the present study was to investigate the association of alcohol consumption with bone strength in Korean adults. Data were from the Korean Genomic Rural Cohort Study, which is an ongoing population-based study of adults aged 40 to 70 years from 5 regions. A total of 7713 participants (3368 men, 4345 women) were surveyed about their annual consumption of alcohol such as soju, beer, makkolli, wine, and whisky. Bone strength was measured by stiffness index using the calcaneal quantitative ultrasound method. Overall, the annual age-specific decrease rate in the stiffness index of women was 2.7 times higher than that of men (0.463% for women, 0.169% for men).After adjustment for eligible covariates, the association between alcohol consumption and risk of reduced bone strength showed a J-shaped curve for both men and women. Compared with nondrinkers, the relative risk of reduced bone strength was 0.52 (95% confidence interval, 0.33-0.83) in men who drank 4 to 5 cups of soju for an amount of 29.626 to 49.375 g of alcohol per day and 0.61 (95% confidence interval, 0.38-0.86) in men who drank 6 to 7 cups of soju for an amount of 49.376 to 69.125 g of alcohol per day. We found no significant relationship between alcohol consumption and bone strength in any other group of men. For women, results suggested that the risk of reduced bone strength was lower in the moderate-consumption group; but no significant relationship was found between alcohol consumption at any level and bone strength. Among Korean adults, alcohol consumption has a J-shaped relationship with risk of reduced bone strength.

Is discordance in bone measurements affected by body composition or anthropometry? A comparative study between peripheral and central devices

Screening of osteoporosis using peripheral bone measurements has become more common, even though diagnostic discrepancies are known to exist between peripheral dual-energy X-ray (pDXA) or quantitative ultrasound (QUS) and central DXA measurements. Values of diagnostic parameters such as bone mineral density, speed of (ultra)sound, and broadband ultrasound attenuation are affected by bone size and soft tissue composition. However, their significance for the discordance between peripheral and central techniques is unclear. In this study, bone status and total body composition of 139 women (mean age 68.3 yr [1.7 SD], mean body mass index 26.5 kg/m2 [3.6 SD]) were assessed by 3 GE Lunar devices. Heel pDXA and heel QUS were conducted using peripheral instantaneous X-ray imaging (PIXI) and Achilles, respectively, and central DXA measurements were taken at the posterior-anterior lumbar spine (L2-L4) and at the left femoral neck using Prodigy. Positive significant associations were found between body height or fat (%) and most DXA or QUS parameters. The discordance between the site-dependent DXA or QUS T-score values typically increased (p<0.05) as a function of body weight or fat (%), but not with body height. On an average, body adiposity accounted for less than 11% of the differences between the techniques; however, increase of total body fat from 20% to 45% led to a discrepancy of one T-score between DXA(HEEL) and QUS(HEEL). To avoid diagnostic bias, comparative assessment of the devices using the same population is recommended.

Bone mineral density assessment: comparison of dual-energy X-ray absorptiometry measurements at the calcaneus, spine, and hip

It is widely accepted that bone mineral density (BMD) measurements obtained by dual-energy X-ray absorptiometry (DXA) at the spine, hip, and calcaneus predict fracture risk. Few published studies to date have examined the relationship between pDXA measurements at the calcaneus to those at the hip and spine. It has been demonstrated that T-score-based criteria cannot be universally applied to all skeletal sites and measurement technologies. Our goal was to define the calcaneal T-score threshold equivalent to low bone mass at the hip or spine. A total of 119 female patients between the ages of 33 and 76 yr of age were recruited at Boston University Medical Center for bone densitometry screening. Bone density measurements were obtained at the calcaneus using the portable Norland Apollo Densitometer (Norland Medical Systems, Fort Atkinson, WI) and at the hip and spine using the Norland Eclipse densitometer. By defining a pDXA T-score < or =-1 as a positive test and DXA scores < or =-1 as the presence of low bone mass, we obtained a specificity of 100% and a sensitivity of 73% (positive predictive value 100% and negative predictive value 80%) in detecting low bone mass at the femoral neck in women over age 65 yr. In women between 40 and 65 yr of age, we obtained a sensitivity of 50% and a specificity of 93% (positive predictive value 93% and negative predictive value 50%) in detecting low bone mass at the femoral neck. In women less than 40 yr of age, we obtained a sensitivity of 13% and a specificity of 100% (positive predictive value 100% and negative predictive value 75%) in detecting low bone mass at the femoral neck. From receiver operating characteristic curves, a calcaneal T-score < or =0.0 detects those with a T-score < or =-1 at the femoral neck and lumbar spine with 100% and 85% sensitivity, respectively. Peripheral DXA of the calcaneus is a sensitive and specific test to diagnose low bone mass in women over 65 yr of age. In women under 65 yr of age, this modality, though not as sensitive, is specific in detecting low bone mass. We conclude that a pDXA calcaneal T-score < or =0 is highly sensitive in predicting osteopenia and osteoporosis at the femoral neck and lumbar spine.

Classification of osteoporosis and osteopenia in men is dependent on site-specific analysis

To examine the diagnosis of osteoporosis and osteopenia in men based on bone density measurements at single or multiple sites using central and peripheral measurements, we studied 206 ambulatory, community-dwelling men over age 50. Bone mineral density of the hip, PA spine, forearm, and finger were assessed by dual-energy X-ray absorptiometry. The diagnosis of osteoporosis based on a single measurement ranged from 1% using the trochanter to 39% using Ward's triangle. Twenty-one percent of men had osteoporosis if the diagnosis was based on at least one osteoporotic value at three central sites (PA spine, total hip, femoral neck). Among these men using T-scores provided by the manufacturers, 51% of osteoporotic patients would be misclassified as normal using the accuDEXA((R)) (finger), and 37% of osteoporotic men would be misclassified as normal using the PA spine. We conclude depending on the number and selection of sites there is considerable variability in the classification and misclassification of osteoporosis and osteopenia in men.

Classification of osteoporosis and osteopenia in postmenopausal women is dependent on site-specific analysis

Despite the availability of guidelines from the World Health Organization study group for the classification of osteoporosis in postmenopausal Caucasian women, confusion still exists about the number of sites used for diagnosis and the clinical utility of peripheral bone mass assessments. To examine the diagnosis of osteoporosis and osteopenia based on bone density measurements at single or multiple sites using central and peripheral measurements, we studied 115 ambulatory, community-dwelling, Caucasian postmenopausal women. Bone mineral density of the hip, PA spine, forearm, and finger were assessed by dual X-ray absorptiometry. Bone mass of the calcaneus was obtained using ultrasound. The diagnosis of osteoporosis based on a single measurement varied from 4% using the trochanteric region to 34% using Ward's triangle, 17% using the calcaneus, and 13% using the finger. Twenty-eight percent of the women had osteoporosis if the diagnosis was based on at least one osteoporotic value at three standard central sites (PA spine, total hip, femoral neck). Among these women, using T-scores provided by the manufacturers, 16% of osteoporotic patients would be misclassified as normal using the Sahara Clinical Bone Sonometer (Hologic, Waltham, MA) (heel) and 34% misclassified using the accuDEXA (Schick, New York, NY) (finger). We conclude that there is significant variability in the classification of osteoporosis based on site selection, with significant potential for misdiagnosis.