Discordance in lumbar spine T-scores and nonstandardization of standard deviations.

Previous studies have demonstrated differences in proximal femur bone mineral density T-scores depending on the reference range used. This subsequently was addressed by the recommended adoption of the National Health and Nutrition Examination Survey III reference range. There is, however, no accepted reference range for interpretation of lumbar spine bone mineral density (BMD), and the use of different reference populations by different manufacturers could result in inconsistencies in diagnosis of osteopenia or osteoporosis. We compared lumbar spine BMD, as well as T- and Z-scores, in 59 women measured using Lunar DPXL and Norland Excel densitometers. BMD measured by the instruments was highly correlated (r = 0.98, p < 0.0001). The instruments however assigned significantly different values when BMD was expressed as T-scores. There were also significant differences in BMD assignments between instruments, when expressed as Z-scores. The observed differences relate to the different young normal mean, and SD employed in calculating the T- and Z scores. To conclude, in the lumbar spine, two commonly used DXA instruments provide comparable absolute values but there are significant differences in derived T-scores due to differences in manufacturer- specific reference ranges. There is a need for standardization of the reference ranges used in the lumbar spine.     

Dual energy x-ray absorptiometry-based assessment of male patients using standardized bone density values and a national reference database.

Dual energy X-ray absorptiometry (DXA) measurements from different manufacturers provide different bone mineral density (BMD) values and derived T-scores and Z-scores. These differences result partly from technical differences in the algorithms for the determination of bone mineral content and bone area and partly from the use of different manufacturer-derived reference databases. The present study was to implement a uniform expression of BMD in all male patients by using standardized BMD (sBMD) values and referring to a newly established national male reference sample. In 8 bone densitometry centers throughout Belgium 229 young healthy men were measured on Hologic (Bedford, MA) or GE-Lunar (Madison, WI) bone densitometers. Quality control procedures were implemented and site cross-calibration performed using the European Spine Phantom. Absolute BMD values were converted to standardized values by validated formulas (sBMD). Clinically acceptable between-center differences were noted. No discrepancy was observed in terms of mean sBMD and standard deviations at the lumbar spine and proximal femur between the Belgian and the US reference populations. Region-specific sBMD thresholds for the diagnosis of male osteoporosis were calculated. The current data provide a basis to implement a nation-wide, uniform expression of BMD in male patients and allow harmonization of the BMD-based diagnosis and treatment of osteoporosis in men.     

DXA-Generated Z-Scores and T-Scores May Differ Substantially and Significantly in Young Adults

Central dual-energy X-ray absorptiometry (DXA) is the gold standard for non-invasive measurement of bone mineral density (BMD). Using this value and subject demographics, DXA software calculates T-scores and Z-scores. Professional society guidelines for the management of osteoporosis are based on T-scores and Z-scores, rather than on the actual BMD value. Although one expects T-scores and Z-scores to be very similar in young men and women for any given BMD measurement, little literature exists on this issue. Our clinical experience shows that some younger adult individuals (premenopausal women and men younger than 50 yr) have larger than expected difference between their DXA T-score and Z-score. This cross-sectional study evaluates the extent of this discordance between Z-scores and T-scores in a sample of 4275 men and women aged 20–49 yr. All subjects were scanned by central DXA using equipment manufactured by GE Lunar, GE, Madison, WI, or Hologic, Inc., Bedford, MA. Significant differences between Z-scores and T-scores were seen within individuals at the lumbar spine, total hip, femoral neck, and trochanter (p value < 0.001) for both DXA systems. Although these differences were less than half a standard deviation (SD) in most instances, the magnitude of difference was substantial at times, being 1 or more SD in up to 11% of cases (range: −1.95 to +1.54 SD). The smallest differences were seen at the total hip and the largest differences were seen at the femoral neck for both technologies. This is in part because there is no single standard Z-score definition, resulting in different methods of calculation across, and even within, DXA manufacturers. Standardization of Z-score definition and method of calculation is indicated. DXA Z-scores should be interpreted with caution in men and women aged 20–50 yr.     

Definition of Osteoporosis by Bone Density Criteria in Men: Effect of Using Female Instead of Male Young Reference Data Depends on Skeletal Site and Densitometer Manufacturer

Whether to use young male or young female reference data to calculate bone mineral density (BMD) T-scores in men remains controversial. The third National Health and Nutrition Examination and Survey (NHANES III) data show that the mean and standard deviation of femoral neck and total hip BMD is greater in young men than young women, and therefore differences in T-scores at these sites using NHANES III female vs male norms becomes less as BMD decreases. In contrast, manufacturer-specific reference databases generally assume similar standard deviations of BMD in men and women. Using NHANES III reference data for the femoral neck and total hip, respectively we found that men with T-scores of −2.5 when young male norms are used have T-scores of −2.4 and −2.3 when young female norms are used. Using manufacturer-specific reference data, we found that men with T-scores of −2.5 when young male norms are used at the femoral neck, total hip, lumbar spine, or one-third of the forearm would have T-scores ranging from −2.4 to −0.4 when young female norms are used, depending on skeletal site and densitometer manufacturer. The change of proportions of men diagnosed with osteoporosis when young female norms are used instead of young male reference data differs substantially according to skeletal site and densitometer manufacturer.     

Diagnostic agreement at the total hip using different DXA systems and the NHANES III database.

In 1997, the National Health and Nutrition Examination Survey III (NHANES III) total hip reference database was adopted for T-score derivation in an effort to optimize diagnostic agreement among densitometers from different manufacturers. Our study was undertaken to evaluate the effectiveness of the NHANES III standardized database at achieving agreement in diagnostic classification (normal, osteopenia, or osteoporosis) based on total hip T-scores comparing 2 different dual-energy X-ray absorptiometry (DXA) systems. This was a retrospective analysis of standard bilateral hip and lumbar spine scans done in duplicate for 60 women scanned on both a GE Lunar Prodigy and Hologic Delphi DXA system. Classification based on lumbar spine T-scores using manufacturer-specific databases was also compared as no standardized lumbar spine reference database exists. Subject's mean age was 62 yr (range: 47-83 yr). There was no statistically significant difference in diagnostic classification between DXA systems (Prodigy vs Delphi), with agreement (same women classified same way) of 92% at the left total hip. Agreement was 100% when T-scores were greater than or equal to -0.8 and less than or equal to -1.2. There was 90% agreement between DXA systems at the lumbar spine. For both hip and spine, all diagnostic discrepancies occurred when the T-scores were at or near transition thresholds between normal and osteopenia or osteopenia and osteoporosis. The difference in mean T-scores between DXA systems at left total hip was 0.11 vs 0.32 for lumbar spine (p less than 0.001). Use of the NHANES III standardized database results in good diagnostic agreement at total hip between Prodigy and Delphi.     

Effects of High-Intensity Resistance Training on Bone Mineral Density in Young Male Powerlifters

The effects of high-intensity resistance training on bone mineral density (BMD) and its relationship to strength were investigated. Lumbar spine (L2-L4), proximal femur, and whole body BMD were measured in 10 male powerlifters and 11 controls using dual-energy X-ray absorptiometry (DXA). There were significant differences in lumbar spine and whole body BMD between powerlifters and controls, but not in proximal femur BMD. A significant correlation was found between lumbar spine BMD and powerlifting performance. These results suggest that high-intensity resistance training is effective in increasing the lumbar spine and whole body BMD. Received: 27 February 1997 / Accepted: 23 March 1998     

A Comparison of Lumbar Spine and Lateral Distal Femur Bone Density in Girls With Rett Syndrome

Introduction/Background: Patients with Rett syndrome (RS) are at risk for low bone mineral density (BMD) and femoral fractures. In patients with RS, assessment with lateral distal femur (LDF) dual-energy X-ray absorptiometry (DXA) is recommended and clinically relevant. This study is the first to assess LDF BMD in girls with RS, and to compare LDF BMD results with lumbar spine BMD results in RS. Method Eleven girls (mean age 8.4 yr) with molecularly diagnosed RS and clinical DXA scan(s) were identified; medical charts were retrospectively reviewed. Baseline and serial lumbar spine and LDF BMD Z-scores were evaluated based on patients’ ambulation status, presence of epilepsy, and mutation type. Results At the time of first scan, 8 of 11 patients had normal lumbar spine BMD and low LDF BMD Z-scores. Two patients had fracture history. Fully ambulatory (3) patients had higher lumbar spine and LDF BMD than partially (5) and nonambulatory (3) patients. Patients with epilepsy had lower average BMD at all sites. No difference was seen in lumbar spine or LDF BMD in patients with high-risk BMD mutations. Seven patients had serial DXA scans with an average observation of 5.1 yr (range 3.1 yr to 6.2 yr). Lumbar spine BMD over time was variable, while LDF bone mass accrual occurred at a lower rate than typically developing girls. Conclusion Females with RS exhibited lower BMD Z-scores at the LDF than at the lumbar spine. LDF and lumbar spine results were discordant. Ambulatory status and the presence of epilepsy were related to BMD. LDF BMD accrual deviated from normal as patients aged.     

Nandrolone decanoate and intranasal calcitonin as therapy in established osteoporosis

This study used a randomized, 2 × 2 factorial design to evaluate over 2 years the effect of intranasal salmon calcitonin and intramuscular nandrolone decanoate on bone mass in elderly women with established osteoporosis. The study was double masked in relation to calcitonin and open in relation to nandrolone decanoate. One hundred and twenty-three women aged 60–88 years who had sustained a previous osteoporotic fracture, or had osteopenia, were recruited through an outpatient clinic. Women were assigned to one of four groups: (1) daily placebo nasal spray, (2) 400 IU intranasal calcitonin daily, (3) 20 intramuscular injections of 50 mg nandrolone decanoate (given as two courses of 10 injections) plus placebo nasal spray, or (4) 20 injections of 50 mg nandrolone decanoate plus 400 IU intranasal calcitonin daily. All subjects received 1000 mg calcium supplementation daily. Outcomes measured included changes in bone mineral density (BMD) at the lumbar spine, as measured by dual-energy quantitative computed tomography (DEQCT), in BMD of the proximal femur, and BMD and bone mineral content (BMC) of the lumbar spine and forearm, as measured by dual-energy X-ray absorptiometry (DXA). Significant positive changes from baseline in DXA BMC at the lumbar spine were observed over 2 years in the calcitonin group (5.0±1.9%, mean ± SE) and in the nandrolone deconate group (4.7±1.9%) but not in the placebo group (1.1±2.2%) or the combined therapy group (0.7±1.8%). Modelling based on the 2×2 factorial design revealed that nandrolone decanoate was associated with a 3.8±1.8% (p<0.05) gain in DXA BMD at the proximal femur. Modelling also revealed that calcitonin treatment was associated with a loss of 11.5±4.7% in DEQCT BMD at the lumbar spine and a loss of 3.7±1.8% in DXA BMD at the proximal femur (p<0.05). There was in vivo antagonism between the two medications of 7.9±3.9% for DXA BMC at the lumbar spine. Both agents caused positive changes from baseline in lumbar spine BMC. Nandrolone decanoate had beneficial effects on BMD at the proximal femur. This dose of intranasal calcitonin was associated with deleterious effects on trabecular BMD at the lumbar spine and total BMD at the proximal femur. There may be significant clinical antagonism between these two medications.     

Increased bone mineral density in Aboriginal and Torres Strait Islander Australians: impact of body composition differences

Bone mineral density (BMD) has been reported to be both higher and lower in Indigenous women from different populations. Body composition data have been reported for Indigenous Australians, but there are few published BMD data in this population. We assessed BMD in 161 Indigenous Australians, identified as Aboriginal (n=70), Torres Strait Islander (n=68) or both (n=23). BMD measurements were made on Norland-XR46 (n=107) and Hologic (n=90) dual-energy X-ray absorptiometry (DXA) machines. Norland BMD and body composition measurements in these individuals, and also in 36 Caucasian Australians, were converted to equivalent Hologic BMD (BMD(H)) and body composition measurements for comparison. Femoral neck (FN) and lumbar spine Z-scores were high in Indigenous participants (mean FN Z-score: Indigenous men +0.98, p<0.0001 vs. mean zero; Indigenous women +0.82, p<0.0001 vs. mean zero). FN BMD(H) was higher in Aboriginal and/or Torres Strait Islander than Caucasian participants, after adjusting for age, gender, diabetes and height and remained higher in men after addition of lean mass to the model. We conclude that FN BMD is higher in Aboriginal and/or Torres Strait Islander Australians than Caucasian Australian reference ranges and these differences still remained significant in men after adjustment for lean mass. It remains to be seen whether these BMD differences translate to differences in fracture rates.     

Development and application of a Japanese model of the WHO fracture risk assessment tool (FRAX™)

Summary The present study estimated the 10-year probability using the Japanese version of WHO fracture risk assessment tool (FRAX™) in order to determine fracture probabilities that correspond to intervention thresholds currently used in Japan and to resolve some issues for its use in Japan. Introduction The objective of the present study was to evaluate a Japanese version of the WHO fracture risk assessment (FRAX™) tool to compute 10-year probabilities of osteoporotic fracture in Japanese men and women. Since lumbar spine bone mineral density (BMD) is used preferentially as a site for assessment, and densitometers use Japanese reference data, a second aim was to investigate the suitability and impact of this practice in Japan. Methods Fracture probabilities were computed from published data on the fracture and death hazards in Japan. Probabilities took account of age, sex, the presence of clinical risk factors and femoral neck BMD. Fracture probabilities were determined that were equivalent to intervention thresholds currently used in Japan. The difference between T-scores derived from international reference data and that using Japanese-specific normal ranges was estimated from published sources. The gradient of risk of BMD for fracture in Japan was compared to that for BMD at the lumbar spine in the Hiroshima cohort. Results The 10-year probabilities of a major osteoporosis-related fracture that corresponded to current intervention thresholds ranged from approximately 5% at the age of 50 years to more than 20% at the age of 80 years. The use of femoral neck BMD predicts fracture as well as or better than BMD tests at the lumbar spine. There were small differences in T-scores between those used for the model and those derived from a Japanese reference population. Conclusions The FRAX™ tool has been used to determine possible thresholds for therapeutic intervention, based on equivalence of risk with current guidelines. The approach will need to be supported by appropriate health economic analyses. Femoral neck BMD is suitable for the prediction of fracture risk among Japanese. However, when applying the FRAX™ model to Japan, T-scores and Z-scores should be converted to those derived from the international reference.     

双能X线骨密度测定腰椎和股骨颈对诊断骨质疏松检出率的比较

目的探讨双能X线吸收法测量腰椎及股骨颈两个不同部位骨密度对骨质疏松诊断的检出率,寻找灵敏度高、更经济实用的筛查骨质疏松的有效方法方法 2011年1月至2012年12月在我院妇科及老年病科住院的女性患者共732人,分别测量腰椎及股骨颈的骨密度T值,进行SPSS统计研究。结果对同一人群通过股骨颈和腰椎不同部位检测发现骨质疏松的检出率分别为25.4%,32.0%;严重骨质疏松的检出率分别为9.0%,27.9%;两者之间差异有统计学意义(P=0.001),腰椎骨密度测量对骨质疏松诊断检出率明显优于股骨颈。根据4个年龄组的股骨颈和腰椎的骨密度T值比较差异均有统计学意义(P均0.01)。结论采用双能X线骨密度测定对诊断骨质疏松腰椎明显优于股骨颈。     

Bone status in primary hyperparathyroidism assessed by regional bone mineral density from the whole body scan and QUS imaging at calcaneus

To assess the bone mineral density status in primary hyperparathyroidism (PHPT), we studied 64 females with PHPT and 17 healthy women. Regional BMD (arms, trunk, legs) from the whole body scan and conventional sites (lumbar spine, femur, radius) were assessed by DXA. Quantitative ultrasound (QUS) imaging measurements were performed at calcaneus. Sixteen women had history of renal lithiasis, 11 had low impact fracture and 37 women had neither renal lithiasis nor fracture. In the entire group, the mean Z-scores were significantly decreased at all sites (lumbar spine, femur, radius). In all clinical subgroups, the mean Z-scores were significantly decreased at radius. The mean Z-scores in premenopausal women were significantly decreased comparatively to postmenopausal women at lumbar spine and femur. In a group of PHPT females matched to controls for age and BMI, only BMD values at radius were lower in PHPT patients than in control (P < 0.03). However, from the whole body scan data, all sites but no trunk were significantly involved in PHPT patients (P < 0.04). Using QUS measurements at calcaneus, the BUA but not SOS in PHPT females was significantly lower (P = 0.03) than in controls. Our results suggest that low BMD at lumbar spine and femur is encountered preferentially in premenopausal women. The BMD decrease predominates at limbs in PHPT with presumably a gradient from proximal to distal part of the limbs. Indeed, the distal part of the limbs are the most affected areas in PHPT whatever the amount of cortical or trabecular bone.     

A Comparison of a Peripheral DXA System with Conventional Densitometry of the Spine and Femur

Because of the perceived high cost of dual-energy X-ray absorptiometry (DXA) studies of the spine and femur, there is renewed interest in small, low-cost X-ray devices for scanning the peripheral skeleton. We have compared forearm bone mineral density (BMD) measurements (distal and ultradistal sites) performed on a DTX-200 (Osteometer MediTech, Hoersholm, Denmark) with spine (L1-L4) and femur (femoral neck and total hip sites) scans performed on a QDR-4500 (Hologic, Waltham, MA) in 172 white UK women aged 22-84 yr with a view to establishing differences caused by inconsistent reference ranges and different age-related changes in BMD. All BMDs were expressed as T-scores using the manufacturers' reference ranges for the forearm and spine, and the National Health and Nutrition Examination Survey (NHANES) ranges for the femur. Linear regression between peripheral and axial sites gave correlation coefficients r = 0.71-0.74 and roof mean standard errors (RMSE) 0.88-1.14 in T-score units. Subjects were divided into the following five age groups: <40 yr; 40-49 yr; 50-59 yr; 60-69 yr and >/=70 yr. A large systematic difference between distal and ultradistal T-scores (mean DeltaT = 0.59, SEM = 0.05) was found affecting all age groups. When the mean difference in T-score between each forearm site (distal, ultradistal) and each axial site (spine, femoral neck, total hip) was examined for premenopausal subjects (n = 58) the mean difference between forearm and axial T-score showed a consistent negative offset (DeltaT = -0.41 to -0.48) for the distal forearm site and a consistent positive offset (DeltaT = +0.30 to +0.37) for the ultradistal site. When interpreting results in postmenopausal women, age-related T-score changes in the forearm were in close agreement with the femoral neck region of exterest (ROI), but systematic differences were found between the forearm and the spine and total hip sites. The two forearm and three axial sites were compared to evaluate the number of postmenopausal subjects identified as osteoporotic on the basis of the World Health Organization (WHO) Study Group criteria (T-score <-2.5). Although forearm and spine T-scores identified approximately equal numbers of subjects as osteoporotic (distal 38/114; ultradistal 31/114; spine 30/114), the two femur sites identified fewer subjects as osteoporotic (femoral neck 25/114; total hip 16/114). The number for the total hip site was statistically significantly smaller than the spine and forearm sites.     

Clinical Evaluation of a Phalangeal Bone Mineral Density Assessment System

Because osteoporosis is common and usually managed in primary care, there is a requirement for cheap and convenient methods of measuring bone mineral density (BMD). AccuDEXA (Lone Oak Medical Technologies, Doylestown, PA) is a tabletop dual-energy X-ray absorptiometry (DXA) device that performs BMD measurements of the hand in the middle phalanges of the third finger. The aims of this study were to (1) evaluate the use of AccuDEXA in UK women; (2) investigate the concordance between AccuDEXA T-scores and DXA T-scores for central (spine and hip) sites; (3) investigate the comparative response of AccuDEXA measurements to clinical risk factors for osteoporosis. Measurements of phalangeal and central BMD were performed in 620 women referred by their family doctors for bone densitometry (group 1) and 159 healthy female volunteers (group 2). For 65 women in group 2, aged 39 yr or younger, the mean Z-scores for AccuDEXA and the central sites calculated from US reference ranges were consistent with the expected value of 0, whereas for the 62 group 2 women, aged 50 yr or older, the mean Z-scores for AccuDEXA and the central sites were in the range 0.4–0.7 and were statistically significantly different from 0. In both group 1 and group 2, the AccuDEXA T-scores in older and younger women were systematically higher than those in the central sites by up to 1 unit. Of the 157 women aged 50 yr or older, with osteoporosis, based on their central DXA results, only 34 (22%) had an AccuDEXA T-score less than or equal to ?2.5, whereas 76 (48%) had osteopenia and 47 (30%) were normal based on their AccuDEXA T-scores. When assessed by the effect of clinical risk factors on Z-scores, both AccuDEXA and central BMD were affected to a similar extent. We conclude that the conventional World Health Organisation T-score criteria for the diagnosis of osteoporosis should not be applied to AccuDEXA measurements in UK women. Clinical risk factors for low BMD were found to affect AccuDEXA measurements to a similar extent as central BMD measurements. AccuDEXA measurements could, therefore, provide an alternative method for identifying individuals with low bone mass, provided care is taken in interpreting T-scores, perhaps, through the use of device-specific thresholds.     

Statut osseux au cours de l'hyperparathyroïdie primitive mesurée par densité minérale osseuse régionale par densitométrie corps entier et ultrasonographie quantitative au calcanéum

To assess the bone mineral density status in primary hyperparathyroidism (PHPT), we studied 64 females with PHPT and 17 healthy women. Regional BMD (arms, trunk, legs) from the whole body scan and conventional sites (lumbar spine, femur, radius) were assessed by DXA. Quantitative ultrasound (QUS) imaging measurements were performed at calcaneus. Sixteen women had history of renal lithiasis, 11 had low impact fracture and 37 women had neither renal lithiasis nor fracture. In the entire group, the mean Z-scores were significantly decreased at all sites (lumbar spine, femur, radius). In all clinical subgroups, the mean Z-scores were significantly decreased at radius. The mean Z-scores in premenopausal women were significantly decreased comparatively to postmenopausal women at lumbar spine and femur. In a group of PHPT females matched to controls for age and BMI, only BMD values at radius were lower in PHPT patients than in control (P <0.03). However, from the whole body scan data, all sites but no trunk were significantly involved in PHPT patients (P <0.04). Using QUS measurements at calcaneus, the BUA but not SOS in PHPT females was significantly lower (P =0.03) than in controls. Our results suggest that low BMD at lumbar spine and femur is encountered preferentially in premenopausal women. The BMD decrease predominates at limbs in PHPT with presumably a gradient from proximal to distal part of the limbs. Indeed, the distal part of the limbs are the most affected areas in PHPT whatever the amount of cortical or trabecular bone.     

The Range of Bone Mineral Density in Healthy Canarian Women by Dual X-ray Absorptiometry Radiography and Quantitative Computer Tomography

Bone mass measurements play a crucial role in the diagnosis of osteoporosis. According to a World Health Organization (WHO) Working Group, osteoporosis in women can be diagnosed if the value for bone mineral density (BMD) is 2.5 or more standard deviations below the mean value of a young reference population. This definition obviously requires the availability of normal data, which should ideally be obtained locally. The objective was establish normal values of BMD in the female Canarian population, by dual X-ray absorptiometry (DXA) in the lumbar spine and the proximal femur, and by quantitative computed tomography (QCT) in the lumbar spine, and to study the correlation between the results of both techniques and the changes with age. Seven hundred forty-four Healthy Canarian women, from 20-80 yr old were examined. Measurement of bone density was performed by an Hologic QDR 1000 densitometer (DXA) in the lumbar spine and proximal femur, and by a Toshiba scanner model 600 HQ in the lumbar spine. Both methods show that the peak bone mass is achieved in the fourth decade (30-39 yr). Bone density decreases thereafter with age in the lumbar spine (r = -0.3364 DXA and r = -0.6988 for QCT) and in the femoral neck (r = -0.3988). Bone density mean values obtained by DXA are very similar to those described in Spain and in other European female populations, using the same densitometer. The correlations between both techniques (DXA and QCT) were high and statistically significant (p < 0.001 in every case). Normal values in the normal Canarian women for DXA and QCT are provided. Our results are very similar to those previously described. These two techniques have a close correlation.     

Bone Loss at the Lumbar Spine and the Proximal Femur in a Rural Japanese Community, 1990–2000: The Miyama Study

Bone mineral density (BMD) was measured over a ten year period in a cohort study in Miyama village, Wakayama Prefecture, Japan, to provide information on rate of bone loss in the mature and elderly population. Four hundred subjects were selected by sex and age decade from the full list of residents born in 1910–1949, and aged 40–79 years at the end of 1989, with 50 men and 50 women in each age decade. Baseline BMD of the lumbar spine and the proximal femur was measured using dual energy X-ray absorptiometry (DXA) in 1990 and again in 1993, 1997 and 2000. Annual rate of change in BMD (% per year) in the lumbar spine in men in their forties, fifties, sixties and seventies was 0.17, 0.55, 0.01 and −0.16, respectively, and in women, −0.87, −0.83, −0.48 and −0.48, respectively. Thus in men, BMD at the lumbar spine increased in all age strata but the oldest, when it decreased, whereas in women, it decreased in all age strata. On the other hand, BMD at the proximal femur decreased in both sexes in all age strata. Our results show that bone loss rates differ depending on the site involved, demonstrating that different strategies are needed for the prevention of bone loss in the spine and hip.  Furthermore, we found evidence of differences in BMD for given age strata between birth cohorts. Data in 1990 and in 2000 showed significant improvements for men in their sixties and for women in their fifties, suggesting that future problems of osteoporosis might be less severe than has previously been predicted in Japan. Received: 11 January 2002 / Accepted: 22 April 2002     

Geographical variation in DXA bone mineral density in young European men and women. Results from the Network in Europe on Male Osteoporosis (NEMO) study

We collected population-based young normal hip and spine BMD data from 17 centres across Europe to assess between centre differences and to compare reference values with the US NHANES-III data. There was strong evidence of between country heterogeneity, but not between centres within countries. Hip BMD mean values were lower in European women, but SD's differed little from the NHANES-III USA results in both sexes. It may be necessary to adjust NHANES-III based T-scores by adding/subtracting a country-specific adjustment factor. INTRODUCTION: It remains unclear whether young normal BMD reference values specific to an American population can be validly used for T-score calculation in Europeans. METHODS: We collected population based BMD data from 1163 men and 329 women aged 19-29 years from 17 centres across Europe to compare mean and SD values with the NHANES-III study USA results. BMD(g/cm2) was measured at the hip and spine using DXA densitometers cross-calibrated with the European Spine Phantom (ESP). The only exclusions were for technically inadequate scans. A linear regression model was used to derive reference values. To allow for direct comparison with published NHANES III study data, the cross-calibrated BMD values were converted using the ESP equations to Hologic QDR 1000 units. RESULTS: In men, the overall mean(SD) BMD values expressed in Hologic-QDR1000 units of measurement, were: femoral neck 0.912(0.132); trochanter 0.793(0.124); and L2-L4 spine 1.027(0.123). The respective estimates in women were: 0.826(0.115); 0.670(0.093); and 0.983(0.107). However the I2 statistic for heterogeneity indicated moderate to strong evidence of between-centre heterogeneity. There was, however, no significant heterogeneity observed between centres within countries, suggesting that this variation arose from national differences. Compared to the NHANES III population-based US data, the mean values in women were significantly lower at both sites due to some lower national European means. However, at all sites and in both sexes the SD's were very similar between the US and Europe. There was some evidence that recruiting volunteers resulted in biased values in women. CONCLUSION: Our T-score normal values for the lumbar spine (L2-L4) should be more reliable for spine-specific risk assessment than some non-representative normal ranges, and should be evaluated for that purpose in Europe. If T-scores are to be used to compare individual data with ranges seen in normal young subjects of the same nationality, it may be necessary to adjust femoral NHANES III-based T-scores by adding (or subtracting) a country-specific adjustment factor. In risk assessment it is probably sufficient to use NHANES III-based hip T-scores, as supplied for the hip by densitometer manufacturers, interpreting them in light of recent international meta-analysis data on the relationship between BMD and fracture risk.     

Comparison of T-scores from different skeletal sites in differentiating postmenopausal women with and without prevalent vertebral fractures.

It is not clear how bone mineral density (BMD) measurements from several regions of lumbar spine and proximal femur should be utilized in assessing fracture risk. We examined how well the newest ISCD recommendations differentiate subjects with and without prevalent vertebral fractures in 187 postmenopausal women presenting for routine bone densitometry. The association between T-scores from proximal femur and lumbar spine sites and the probability of having a vertebral fracture was modeled via logistic regression with adjustment for age. The lowest T-score of any hip or spine sites (the current ISCD recommendation) and the proximal femur measurements, particularly the femoral neck and total hip, displayed the strongest association with the probability of vertebral fractures.Subjects with a T-score < -2.5 at multiple hip sites had a higher probability of having a vertebral fracture. The sensitivity and specificity associated with particular T-score cutoff values varied greatly depending on the site of measurement.Consequently, T-score values from different sites that had comparable sensitivity/specificity for detecting the presence of vertebral fractures differed by as much as 1.5 T-score units. This finding implies that a single cutoff value, such as -2.5, might not be clinically acceptable when applied to T-scores from different sites.     

Heterogeneity of Bone Mineral Density Across Skeletal Sites and Its Clinical Implications

Low trauma fractures in the elderly are highly predictable by measurement of bone mineral density (BMD). Preventive measures for low BMD, such as hormone replace therapy (HRT), have potential risks. Thus, a rational decision on HRT or other therapy critically depends on an accurate diagnosis of osteopenia/osteoporosis. We assessed the degree of diagnostic heterogeneity based on spine and hip BMD for 2313 women. We found: 1. In ~30.0% of cases, the difference between spine and hip Z- and T-scores was >1.0, and in 20.8% (Z-scores) and 15.2% (T-scores) the difference was >2.0. 2. With increasing age, the proportions of women with Z- or T-scores greater at the hip than the spine generally decreased. 3. The correlation between hip and spine and Z- and T-scores ranged from 0.50 to 0.72, and generally decreased with increasing age. 4. If screened only at the hip or spine, 17.9/27.3% with osteopenia and 1.3/2.9% with osteoporosis at either site would be diagnosed as normal. Corresponding analyses of 143 men yielded similar results. Therefore, if possible, dual X-ray absorptiometry (DXA) of both the spine and hip should be performed for an accurate assessment of osteoporosis at these two most frequently fractured sites. If only one site is chosen, measurement of the hip is preferred to measurement of the spine.