Bone mineral density reference range in Estonia: a comparison with the standard database (NHANES III)

Factors associated with the accuracy of self-reported osteoporosis in the community

We examined the agreement between self-reported osteoporosis and bone mineral density (BMD) results through dual-energy x-ray absorptiometry (DXA) using data from a national representative sample taken from the US communities. Six-year data from the continuous National Health and Nutrition Examination Survey 2005-2006, 2007-2008, and 2009-2010 were merged. Participants included adults 50 years of age or older whose data appeared in both questionnaire and medical examination data files. Self-reported osteoporosis was defined by an affirmative response to a question in the osteoporosis questionnaire then compared with BMD-defined osteoporosis, defined by BMD values taken from the examination data. Agreement between self-reported osteoporosis and DXA results were low. Kappa was only 0.24 (95 % confidence interval = 0.21-0.27), and sensitivity and positive predictive value were 28.0 and 40.8 %, respectively. When stratified by gender or age group, agreement remained poor. Self-report of osteoporosis would not be suitable for accurate prevalence estimates for osteoporosis regardless of gender or age group.

Different reference BMDs affect the prevalence of osteoporosis

The T score represents the degree of deviation from the peak bone mineral density (BMD) (reference standard) in a population. Little has been investigated concerning the age at which the BMD reaches the peak value and how we should define the reference standard BMD in terms of age ranges. BMDs of 9,800 participants were analyzed from the Korean National Health and Nutrition Examination Survey database. Five reference standards were defined: (1) the reference standard of Japanese young adults provided by the dual-energy X-ray absorptiometry machine manufacturer, (2) peak BMD of the Korean population evaluated by statistical analysis (second-order polynomial regression models), (3) BMD of subjects aged 20-29 years, (4) BMD of subjects aged 20-39 years, and (5) BMD of subjects aged 30-39 years. T-scores from the five reference standards were calculated, and the prevalence of osteoporosis was evaluated and compared for males and females separately. The peak BMD in the polynomial regression model was achieved at 26 years in males and 36 years in females in the total hip, at 20 years in males and 27 years in females in the femoral neck, and at 20 years in males and 30 years in females in the lumbar spine. The prevalence of osteoporosis over the age of 50 years showed significant variation of up to two fold depending on the reference standards adopted. The age at which peak BMD was achieved was variable according to the gender and body sites. A consistent definition of peak BMD needs to be established in terms of age ranges because this could affect the prevalence of osteoporosis and healthcare policies.

Country-specific young adult dual-energy X-ray absorptiometry reference data are warranted for T-score calculations in women: data from the peak-25 cohort

The aims of this study were to provide normative data for dual-energy X-ray absorptiometry (DXA) in 25-yr-old women and evaluate whether young adult Swedish women have bone mineral density (BMD) comparable with DXA manufacturer reference values and other equivalent populations. BMD at all sites was measured in the population-based Peak-25 cohort (n = 1061 women; age, 25.5 ± 0.2yr). BMD values were standardized (sBMD) and compared against the Third National Health and Nutrition Examination Survey (NHANES III) and other cohorts. Based on the DXA manufacturer-supplied reference values, Z-scores were 0.54 ± 0.98 (femoral neck [FN]), 0.47 ± 0.96 (total hip [TH]), and 0.32 ± 1.03 (lumbar spine [LS]). In comparison with other studies, sBMD was higher in the Peak-25 cohort (FN, 1.5%-8.3%; TH, 3.9%-9.2%; and LS, 2.4%-6.5%) with the exception of trochanter-sBMD which was 2.5% lower compared with NHANES III. The concordance in identifying those in the lowest or highest quartile of BMD was highest between hip measurements (low, 71%-78% and high, 70%-84%), corresponding discordance of 0%-1%. At this age, the correlation between DXA sites was strong (r = 0.62-0.94). BMD in Swedish young adult women is generally higher than has been reported in other equivalently aged European and North American cohorts and suggests that the high fracture incidence in Sweden is not explained by lower peak bone mass. The use of nonregional-specific DXA reference data could contribute to misdiagnosed osteoporosis in elderly women.

Importance of ethnic base standard references for the diagnosis of osteoporosis in Thai women

Many studies demonstrated the importance of using ethnic-specific normal database in the diagnosis of osteoporosis (OP). Aims of this study were to assess diagnostic agreement, prevalence of OP, and diagnostic misclassification between Caucasian, Japanese, and Thai normal databases. The cross-sectional study of 3181 Thai women who had bone mineral density (BMD) measurement between January 2008 and December 2010 was performed. BMDs at lumbar spine (LS), femoral neck (FN), and total hip (TH) were derived to T-score by using Caucasian, Japanese, and Thai standard references. Kappa statistic was used to assess diagnostic agreement and misclassification. Diagnostic agreements between Caucasian and Thai reference databases were 0.39 for LS and 0.90 for FN. No statistical agreement was found in TH region (0.01, p value=0.264). Applying the Japanese reference, diagnostic agreements were 0.71 for LS, 0.76 for FN, and 0.94 for TH regions. Prevalence of OP in postmenopausal women was 64.1%, 37.7%, and 41.4% using Caucasian, Japanese, and Thai standard references. Percentage of misclassification was varied by menopausal status and reference database from 11.2% to 48.7%. When applying Japanese databases instead of Caucasian normal databases, overall diagnostic misclassification decreased from 35.1% to 16.1%. Choice of reference database has a significant effect on the diagnosis of low bone mass and OP. Japanese reference database has better diagnostic agreement with previously studied Thai reference database in 1999 than Caucasian reference database.

Impact of a new sarco-osteopenia definition on health-related quality of life in a population-based cohort in Northern Europe

Sarcopenia has been shown to be a marker of falling; therefore, combining osteopenia and sarcopenia could identify a frailer, higher-fracture-risk population. We aimed to define sarco-osteopenia (SOP) in a population-based healthy young sample using both muscle functional and quantitative parameters and assessing the impact of this definition on health-related quality of life. A population sample of 304 patients aged 25-70 yr was analyzed with a Lunar DPX-IQ dual-energy X-ray absorptiometry machine (GE Healthcare, Pollards Wood, UK), and their health-related quality of life was assessed with the Short-Form-36 (SF-36) questionnaire. SOP was defined as bone mineral density (BMD) -1 standard deviation (SD) and height-adjusted appendicular muscle mass -2 SD and/or grip strength -2 SD less than the mean values of 77 young individuals in the population sample (age: 25-39 yr). Our proposed SOP definition identifies 3-9% of the population older than 40 yr as sarco-osteopenic. These individuals also show markedly lower scores in the role-physical (p=0.01), vitality (p=0.03), and role-emotional (p=0.02) subscales of the SF-36 questionnaire. No difference in the quality of life was observed between osteopenic individuals and those with normal BMD. The new definition identifies a population with significant decrements in health-related quality of life.