Adiposity and bone microarchitecture in the GLOW study.

Low body mass index (BMI) is an established risk factor for fractures in postmenopausal women but the interaction of obesity with bone microarchitecture is not fully understood. In this study, obesity was associated with more favourable bone microarchitecture parameters but not after parameters were normalised for body weight. INTRODUCTION: To examine bone microarchitecture in relation to fat mass and examine both areal bone mineral density (aBMD) and microarchitecture in relation to BMI categories in the UK arm of the Global Longitudinal Study of Osteoporosis in Women. METHODS: Four hundred and ninety-one women completed questionnaires detailing medical history; underwent anthropometric assessment; high-resolution peripheral quantitative computed tomography (HRpQCT) scans of the radius and tibia and DXA scans of whole body, proximal femur and lumbar spine. Fat mass index (FMI) residuals (independent of lean mass index) were derived. Linear regression was used to examine HRpQCT and DXA aBMD parameters according to BMI category (unadjusted) and HRpQCT parameters in relation to FMI residuals (with and without adjustment for anthropometric, demographic and lifestyle covariates). RESULTS: Mean (SD) age was 70.9 (5.4) years; 35.0% were overweight, 14.5% class 1 obese and 7.7% class 2/3 obese. There were significant increasing trends according to BMI category in aBMD of whole body, hip, femoral neck and lumbar spine (p ≤ 0.001); cortical area (p < 0.001), thickness (p < 0.001) and volumetric density (p < 0.03), and trabecular number (p < 0.001), volumetric density (p < 0.04) and separation (p < 0.001 for decreasing trend) at the radius and tibia. When normalised for body weight, all HRpQCT and DXA aBMD parameters decreased as BMI increased (p < 0.001). FMI residuals were associated with bone size and trabecular architecture at the radius and tibia, and tibial cortical microarchitecture. CONCLUSION: Significant trends in HRpQCT parameters suggested favourable bone microarchitecture at the radius and tibia with increasing BMI but these were not proportionate to increased weight.

Self-perceived Fracture Risk in the Global Longitudinal Study of Osteoporosis in Women: Its Correlates and Relationship with Bone Microarchitecture.

The purpose of this study is to examine correlates of self-perceived fracture risk (SPR) and relationships between SPR and subsequent bone density and microarchitecture in the UK arm of the Global Longitudinal Study of Osteoporosis in Women. 3912 women completed baseline questionnaires detailing medical history and SPR; 492 underwent HRpQCT scans of the radius and tibia and DXA scans of total body, hip, femoral neck and lumbar spine a median of 7.5 years later. Correlates of SPR were examined and a cluster analysis of potential predictors of SPR performed. SPR in relation to HRpQCT and aBMD parameters was examined using linear regression with and without adjustment for anthropometric, demographic and lifestyle covariates. Mean (SD) baseline age was 69.0 (9.0) years; 56.6% reported a similar SPR; 28.6% lower SPR; 14.9% higher SPR compared to women of similar age. In mutually-adjusted analysis, higher SPR was associated (p < 0.05) with: lower physical activity and educational attainment; use of anti-osteoporosis medications (AOM) and calcium supplements; greater number of falls in the previous year; history of fracture since aged 45; family history of hip fracture; and increased comorbidity. Higher SPR, history of fracture, and use of AOM, calcium and vitamin D clustered together. Even after adjustments that included AOM use, higher SPR was associated with: lower radial trabecular volumetric density and number, and higher trabecular separation; lower tibial cortical area and trabecular volumetric density; and lower aBMD at the femoral neck. Despite greater AOM use, women with higher baseline SPR had poorer subsequent bone health.

Bone Phenotype Assessed by HRpQCT and Associations with Fracture Risk in the GLOW Study.

The epidemiology and pathogenesis of fractures in postmenopausal women has previously been investigated in the Global Longitudinal study of Osteoporosis in Women (GLOW). To date, however, relationships between bone imaging outcomes and fracture have not been studied in this cohort. We examined relationships between high-resolution peripheral quantitative computed tomography (HRpQCT) parameters and fracture in the UK arm of GLOW, performing a cluster analysis to assess if our findings were similar to observations reported from older participants of the Hertfordshire Cohort Study (HCS), and extended the analysis to include tibial measurements. We recorded fracture events and performed HRpQCT of the distal radius and tibia and dual-energy X-ray absorptiometry (DXA) of the hip in 321 women, mean age 70.6 (SD 5.4) years, identifying four clusters at each site. We saw differing relationships at the radius and tibia. Two radial clusters (3 and 4) had a significantly lower hip areal bone mineral density (p < 0.001) compared to Cluster 1; only individuals in Cluster 4 had a significantly higher risk of fracture (p = 0.005). At the tibia, clusters 1, 3 and 4 had lower hip areal bone mineral density (p < 0.001) compared to Cluster 2; individuals in Cluster 3 had a significantly higher risk of fracture (p = 0.009). In GLOW our findings at the radius were very similar to those previously reported in the HCS, suggesting that combining variables derived from HRpQCT may give useful information regarding fracture risk in populations where this modality is available. Further data relating to tibial HRpQCT-phenotype and fractures are provided in this paper, and would benefit from validation in other studies. Differences observed may reflect age differences in the two cohorts.

Self-perception of fracture risk: what can it tell us?

In this study, we report that self-perception of fracture risk captures some aspect of fracture risk not currently measured using conventional fracture prediction tools and is associated with improved medication uptake. It suggests that adequate appreciation of fracture risk may be beneficial and lead to greater healthcare engagement and treatment. INTRODUCTION: This study aimed to assess how well self-perception of fracture risk, and fracture risk as estimated by the fracture prediction tool FRAX, related to fracture incidence and uptake and persistence of anti-osteoporosis medication among women participating in the Global Longitudinal study of Osteoporosis in Women (GLOW). METHODS: GLOW is an international cohort study involving 723 physician practices across 10 countries in Europe, North America and Australia. Aged ≥ 55 years, 60,393 women completed baseline questionnaires detailing medical history, including co-morbidities, fractures and self-perceived fracture risk (SPR). Annual follow-up included self-reported incident fractures and anti-osteoporosis medication (AOM) use. We calculated FRAX risk without bone mineral density measurement. RESULTS: Of the 39,241 women with at least 1 year of follow-up data, 2132 (5.4%) sustained an incident major osteoporotic fracture over 5 years of follow-up. Within each SPR category, risk of fracture increased as the FRAX categorisation of risk increased. In GLOW, only 11% of women with a lower baseline SPR were taking AOM at baseline, compared with 46% of women with a higher SPR. AOM use tended to increase in the years after a reported fracture. However, women with a lower SPR who were fractured still reported lower AOM rates than women with or without a fracture but had a higher SPR. CONCLUSIONS: These results suggest that SPR captures some aspect of fracture risk not currently measured using conventional fracture prediction tools and is also associated with improved medication uptake.

Non-invasive Assessment of Lower Limb Geometry and Strength Using Hip Structural Analysis and Peripheral Quantitative Computed Tomography: A Population-Based Comparison.

Hip fracture is the most significant complication of osteoporosis in terms of mortality, long-term disability and decreased quality of life. In the recent years, different techniques have been developed to assess lower limb strength and ultimately fracture risk. Here we examine relationships between two measures of lower limb bone geometry and strength; proximal femoral geometry and tibial peripheral quantitative computed tomography. We studied a sample of 431 women and 488 men aged in the range 59-71 years. The hip structural analysis (HSA) programme was employed to measure the structural geometry of the left hip for each DXA scan obtained using a Hologic QDR 4500 instrument while pQCT measurements of the tibia were obtained using a Stratec 2000 instrument in the same population. We observed strong sex differences in proximal femoral geometry at the narrow neck, intertrochanteric and femoral shaft regions. There were significant (p < 0.001) associations between pQCT-derived measures of bone geometry (tibial width; endocortical diameter and cortical thickness) and bone strength (strength strain index) with each corresponding HSA variable (all p < 0.001) in both men and women. These results demonstrate strong correlations between two different methods of assessment of lower limb bone strength: HSA and pQCT. Validation in prospective cohorts to study associations of each with incident fracture is now indicated.