Journal of Clinical Densitometry - Articles in Press

In vivo Precision of the GE Lunar iDXA Densitometer for the Measurement of Total-Body, Lumbar Spine, and Femoral Bone Mineral Density in Adults - Corrected Proof

Karen Hind, Brian Oldroyd, John G. Truscott — 2010-08-13

Abstract: Knowledge of precision is integral to the monitoring of bone mineral density (BMD) changes using dual-energy X-ray absorptiometry (DXA). We evaluated the precision for bone measurements acquired using a GE Lunar iDXA (GE Healthcare, Waukesha, WI) in self-selected men and women, with mean age of 34.8yr (standard deviation [SD]: 8.4; range: 20.1–50.5), heterogeneous in terms of body mass index (mean: 25.8kg/m2; SD: 5.1; range: 16.7–42.7kg/m2). Two consecutive iDXA scans (with repositioning) of the total body, lumbar spine, and femur were conducted within 1h, for each subject. The coefficient of variation (CV), the root-mean-square (RMS) averages of SDs of repeated measurements, and the corresponding 95% least significant change were calculated. Linear regression analyses were also undertaken. We found a high level of precision for BMD measurements, particularly for scans of the total body, lumbar spine, and total hip (RMS: 0.007, 0.004, and 0.007g/cm2; CV: 0.63%, 0.41%, and 0.53%, respectively). Precision error for the femoral neck was higher but still represented good reproducibility (RMS: 0.014g/cm2; CV: 1.36%). There were associations between body size and total-body BMD and total-hip BMD SD precisions (r=0.534–0.806, p<0.05) in male subjects. Regression parameters showed good association between consecutive measurements for all body sites (r2=0.98–0.99). The Lunar iDXA provided excellent precision for BMD measurements of the total body, lumbar spine, femoral neck, and total hip.

Dual-Energy X-ray Absorptiometry With Serum Ferritin Predicts Liver Iron Concentration and Changes in Concentration Better Than Ferritin Alone - Corrected Proof

2010-07-22

Abstract: Accurate assessment of liver iron concentration (LIC) is critical for optimal monitoring of iron toxicity in multitransfused patients. Serum ferritin is the most widely used although its association to LIC is only modest. We studied if a liver-specific measure using dual-energy X-ray absorptiometry (DXA) systems could improve LIC estimates over ferritin alone in Thalassemia (Thal) patients. Thirty-seven patients with Thal (19.2±9.0yr, 20 male) were studied and 10 had multiple visits. Height, weight, ferritin, whole-body DXA, and hepatic superconducting quantum interference device (SQUID) were measured within 5wk. DXA hepatic density was measured using right rib, whole liver, and multiple subliver regions. The best agreement to SQUID LIC was found using a combination of ferritin, weight, DXA subliver region 3 bone mineral content (BMC), and right rib BMC. DXA with ferritin improved the ferritin alone correlation from R2=0.35 to R2=0.62. Serial LIC changes using DXA were associated with serial SQUID changes (r=0.73, p=0.02). Changes in ferritin alone were not significant (p=0.06). We conclude that the addition of whole-body DXA measures and body weight substantially increased the accuracy of LIC and change in LIC estimates over the use of ferritin alone and could be useful when magnetic resonance imaging or SQUID is not available.

International Society for Clinical Densitometry Official Positions: Asia-Pacific Region Consensus - Corrected Proof

2010-07-22

Abstract: The International Society for Clinical Densitometry (lSCD) is a nonprofit multidisciplinary international professional organization. The ISCD mission is to advance excellence in the assessment of skeletal health. To achieve this mission, the ISCD has conducted a number of Position Development Conferences over the past 10yr, bringing together international experts to review and create evidence-based position statements guiding clinicians involved in the area. The Asia-Pacific (AP) Panel of the ISCD was formed to give regional input to the ISCD from the AP Region and to oversee ISCD education and certification programs in the region. An AP Panel consensus meeting recently reviewed the most current Official Positions of the ISCD in view of the different population characteristics and health standards in the region. The reviewed position statements included those for bone testing by central and peripheral devices but did not include ISCD Official Positions on Vertebral Fracture Assessment or pediatric bone mineral density.

BMD Reference Standards Among South Asians in the United States - Corrected Proof

2010-07-22

Abstract: The relationship between bone mineral density (BMD) and fracture risk is not well established for non-white populations. There is no established BMD reference standard for South Asians. Dual-energy X-ray absorptiometry (DXA) was used to measure BMD at total hip and lumbar spine in 150 US-based South-Asian Indians. For each subject, T-scores were calculated using BMD reference values based on US white, North Indian, and South Indian populations, and the resulting WHO BMD category assignments were compared. Reference standards derived from Indian populations classified a larger proportion of US-based Indians as normal than did US white-based standards. The percentage of individuals reclassified when changing between reference standards varied by skeletal site and reference population origin, ranging from 13% (95% confidence interval [CI]: 7–18%), when switching from US white- to North Indian-based standard for total hip, to 40% (95% CI: 32–48%), when switching from US white to South Indian reference values for lumbar spine. These findings illustrate that choice of reference standard has a significant effect on the diagnosis of osteoporosis in South Asians, and underscore the importance of future research to quantify the relationship between BMD and fracture risk in this population.

Hypovitaminosis D and Bone Mineral Metabolism and Bone Density in Hyperthyroidism - Corrected Proof

2010-07-22

Abstract: Little is known about the impact of concomitant vitamin D deficiency on bone mineral density in hyperthyroidism. Therefore, we evaluated bone mineral measures in vitamin D–deficient and sufficient patients with hyperthyroidism. Thirty newly diagnosed consecutive patients with hyperthyroidism were included. Blood samples were used for measurement of calcium, phosphate, alkaline phosphatase, 25-hydroxy vitamin D [25(OH) D], and parathyroid hormone (PTH). Bone mineral density (BMD) was measured at the hip, spine, and forearm. The patients were divided into vitamin D–deficient (<25nmol/L) and vitamin D–sufficient groups (≥25nmol/L). Eight (26.6%) patients had 25(OH) D levels less than 25nmol/L, with mean±standard deviation (SD) level of 16.5±3.2 (vitamin D–deficient group 1), and the remainder had a mean±SD of 46.0±13.5nmol/L (vitamin D–sufficient group 2). Serum-intact PTH levels were significantly higher in group 1 compared with those in group 2 (31.2±16.3 vs 18.0±13.1pg/mL; p=0.041). In the vitamin D–deficient group, the mean BMD T-scores were in the osteoporotic range at hip and forearm (−2.65±1.13 and −3.04±1.3) and in the osteopenia range at lumbar spine (−1.83±1.71). However, in vitamin D–sufficient group, the mean BMD T-scores were in the osteopenia range (−1.64±1.0, −1.27±1.6, and −1.60±0.7) at hip, forearm, and lumbar spine, respectively. The mean BMD Z-scores were also significantly lower in vitamin D–deficient group compared with those in vitamin D–sufficient group. Finally, BMD values (gm/cm2) at the hip and forearm were significantly lower in the vitamin D–deficient group compared with those in the vitamin D–sufficient group. In conclusion, hyperthyroid patients with concomitant vitamin D deficiency had lower BMD compared with vitamin D–sufficient patients.

Prevalence of Bone Mineral Density Abnormalities and Related Risk Factors in an Ambulatory HIV Clinic Population - Corrected Proof

2010-07-22

Abstract: Bone mineral density (BMD) abnormalities are observed frequently among human immunodeficiency virus (HIV)-infected patients. Risk factors for reduced BMD in the setting of HIV have been previously studied, but detailed antiretroviral treatment history is often not available. A cross-sectional observational study was conducted between 2005 and 2007 among unselected HIV-infected adults attending an ambulatory urban HIV clinic. Dual-energy X-ray absorptiometry (DXA) scans of lumbar spine and femoral neck, full laboratory profile, detailed questionnaire, and antiretroviral history were obtained. Univariate and multivariate logistic regression analyses were performed to investigate factors associated with BMD below the expected range for age. Two hundred ninety patients completed the study: 80% Caucasians, 89% males, with median age of 49yr. Low BMD as assessed by Z-score was present in 19.7% of the patients. By multivariate analysis, only lower body mass index (BMI) was an independent risk factor for low BMD. Cumulative exposure to protease inhibitors, non-nucleosides, and individual nucleoside and nucleotide analogs were not independently associated with low BMD. In conclusion, a 19.7% prevalence of abnormal BMD by DXA scan was identified in an unselected group of HIV-infected adults. Lower BMI was independently associated with low BMD. No correlation was found between abnormal BMD and cumulative exposure to any antiretroviral agents.

Assessing Bone Microstructure at the Distal Radius in Children and Adolescents Using HR-pQCT: A Methodological Pilot Study - Corrected Proof

2010-07-22

Abstract: We examined the use of high-resolution peripheral quantitative computed tomography (HR-pQCT [XtremeCT; Scanco Medical, Switzerland]) to assess bone microstructure at the distal radius in growing children and adolescents. We examined forearm radiographs from 37 children (age 8–14yr) to locate the position of the ulnar and radial growth plates. We used HR-pQCT to assess bone microstructure in a region of interest (ROI) at the distal radius that excluded the growth plate (as determined from the radiographs) in all children (n=328; 9–21 yr old). From radiographs, we determined that a ROI in the distal radius at 7% of bone length excluded the radial growth plate in 100% of participants. We present bone microstructure data at the distal radius in children and adolescents. From the HR-pQCT scans, we observed active growth plates in 80 males (aged 9.5–20.7yr) and 92 females (aged 9.5–20.2yr). The ulnar plate was visible in 9 male and 17 female participants (aged 11.2±1.9yr). The HR-pQCT scan required 3min with a relatively low radiation dose (<3μSv). Images from the radial ROI were free of artifacts and outlined cortical and trabecular bone microstructure. There is currently no standard method for these measures; therefore, these findings provide insight for investigators using HR-pQCT for studies of growing children.

Risk Communication and Shared Decision Making in the Care of Patients With Osteoporosis - Corrected Proof

E. Michael Lewiecki — 2010-07-22

Abstract: Health maintenance and disease management require vigilance in assessing risk, communicating risk, and balancing the expected benefits of therapeutic interventions with potential harms. The evaluation of skeletal health includes identification of clinical risk factors for fracture, bone density testing in appropriate patients, and the use of validated algorithms for estimating the probability of fracture. To reduce the burden of osteoporotic fractures, patients at risk for fracture must be identified and treated with effective agents that are taken regularly, correctly, and for a sufficient length of time to achieve the desired benefit. These goals may be enhanced by shared decision making, a process by which the clinician and the patient share all applicable information and negotiate a plan of treatment that is acceptable to both. As an educator and a partner in making treatment decisions, the clinician must be familiar with the medical evidence and able to discuss complex medical information in a manner that is understood by the patient, with appropriate consideration of the patient's expectations, beliefs, and concerns. After treatment is started, risk communication, patient education, and shared decision making should be continued in an effort to maintain good compliance and persistence with therapy. Further study is needed to identify and validate optimal risk communication tools for the care of patients with osteoporosis. Challenges to shared decision making include competition from other health care priorities for limited patient encounter time during office visits, poor reimbursement, insufficient knowledge of the medical evidence, inadequate communication skills, and cognitive/affective disorders limiting patient participation in making treatment decisions.

Effect of Precision on Longitudinal Follow-Up of Bone Mineral Density Measurements in Elderly Women and Men - Corrected Proof

Janaka Lenora, Kristina Åkesson, Paul Gerdhem — 2010-06-07

Abstract: Precision error of dual-energy X-ray absorptiometry exceeds the expected annual rate of bone loss in the elderly. The capacity to detect changes in areal bone mineral density (aBMD; g/cm2) over a 5-yr period was assessed. Six hundred ninety-one women, 75.2 (0.1)yr, from the Malmö OPRA-study, were measured using Lunar DPX-L (GE Lunar, Madison, WI), and 211 men, 74.7 (3.2)yr, from the Malmö Mr Os-study, were measured using Lunar Prodigy (GE Lunar) with follow-up 5yr later. Precision error was determined with 30 degrees of freedom. Least significant change (LSC, i.e., 2.77×precision error) was calculated. Women's precision errors (g/cm2) for DPX-L were 0.028 (total hip [TH]) and 0.016 (lumbar spine [LS]), and for Prodigy, they were 0.009 (TH) and 0.039 (LS). In men, corresponding results for Prodigy were 0.014 and 0.031. In women, 41% and in men, 39% had aBMD changes exceeding the LSC at TH. Follow-up intervals (i.e., LSC/median rate of aBMD change) for both women and men were 8yr (TH) and 13yr (LS). Based on Prodigy precision data, follow-up intervals for women were 3 and 32yr at TH and LS. In summary, several years were needed to detect change. Only when a high rate of bone loss is suspected, a short follow-up time is possible, in elderly persons.