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Older adults with lower social networks may disproportionately participate more in high fall-risk activities to maintain their independence; thus increasing fall risk. We followed 8,412 white participants in the Study of Osteoporotic Fractures (mean age 77 [+ or -] 5 years) for falls over 3 years. Falls were reported every 4 months using postcard mailings and were 95% complete. The Lubben Social Network Scale was used to assess social networks at baseline (high scores= higher networks). Poisson regression with generalized estimating equations was used to compare fall rates across social network levels. Women fell on average 0.63 times yearly, 95% CI (0.60, 0.66). Crude annual fall rates decreased with increasing social network quartiles--0.75, 0.58, 0.55, 0.49. Adjusting for demographics, function, medical history, and lifestyle, low social networks (1st quartile v all others) were associated with increased falls, RR=1.15 (95% CI: 1.01, 1.31). Findings suggest social networks predict fills in older community-dwelling women.

Introduction: The purpose of this study was to examine the relationships of vitamin D supplementation and serum concentrations of vitamin D metabolites and parathyroid hormone (PTH) with neuromuscular function and falls in older community-dwelling women. Methods: We examined these relationships using a 4-year prospective multi-center study among 9,526 community-dwelling women enrolled in the Study of Osteoporotic Fractures (median age: 70 years; interquartile range: 67-75) and a subset of 389 women (97%) out of 400 who were randomly selected from the entire cohort for serum measures. Measurements included: vitamin D supplementation, serum 25-hydroxyvitamin D3 [25(OH)D3], serum 1,25-dihydroxyvitamin D3 [1,25(OH) 2D3], and serum intact parathyroid hormone (iPTH); grip and quadriceps strength, chair-stand time, walking speed, reaction time, and balance-walk time (including changes in grip strength, chair-stand time, walking speed and balance-walk time over approximately 3.7 years); and incident fall rates (number of falls/woman-years). Results: In 9,526 women, vitamin D supplementation was not associated with any measures of neuromuscular function, change in neuromuscular function, or fall rates (p>0.01 for all). In a subgroup of 389 women, there was a trend of higher 25(OH)D3 concentration with slightly weaker grip strength (p=0.007), and women in the fourth quartile of 1,25(OH)2D3 had a faster chair-stand time (p=0.017) than women in the first quartile; still, in general, concentrations of 25(OH)D3, 1,25(OH)2D3, and iPTH were not associated with either neuromuscular function or changes in neuromuscular function (p>0.05 for all). However, higher 1,25(OH)2D3 concentration was associated with lower fall rates (p=0.039). Conclusions: Higher 1,25(OH)2D3 concentration is associated with a lower fall risk in older community-dwelling women, but vitamin D supplementation, and 25(OH)D3 and iPTH concentrations are not associated with either neuromuscular function or falls. [ABSTRACT FROM AUTHOR]

Osteoporotic fractures are less prevalent in African Americans than in caucasians, possibly because of differences in bone structural strength. Bone structural adaptation can be attributed to changes in load, crudely measured as lean and fat mass throughout life. The purpose of this analysis was to describe the associations of leg lean mass, total body fat mass, and hours walked per week with femoral bone mineral density (BMD) and bone geometry in a cross-sectional sample of 1,748 men of African descent between the ages of 40 and 79 years. BMD, section modulus (Z), cross-sectional area (CSA), and subperiosteal width were measured from dual energy X-ray absortiometry (DXA) scans using the hip structural analysis (HSA) program. Multiple linear regression models explained 35% to 48% of the variance in bending (Z) and axial (CSA) strength at the femoral neck and shaft. Independent of all covariates including total body fat mass, one standard deviation increase in leg lean mass was significantly associated with a 5% to 8% higher Z, CSA, and BMD (P < 0.010) at the neck and shaft. The number of hours walked per week was not a strong or consistent independent predictor of bone geometry or BMD. We have shown that weight is the strongest independent predictor of femur BMD and geometric strength although the effect appears to be mediated by lean mass since leg lean mass fraction and total body fat mass fraction had significant and opposing effects at the narrow neck and shaft in this group of middle aged and elderly men. [ABSTRACT FROM AUTHOR]

Calcaneal broadband ultrasound attenuation (BUA) is an independent predictor of hip and vertebral fractures. BUA is under genetic control, but the specific genes contributing to BUA are not well defined. We examined the relationship between genetic variation in alpha2HS-glycoprotein (AHSG), an abundant noncollagenous protein of bone matrix, and calcaneal BUA. Genetic polymorphism in AHSG was determined in 222 Caucasian women (age 66-92) enrolled in the Pittsburgh Study of Osteoporotic Fractures clinical center by isoelectric focusing of serum samples. Calcaneal BUA and bone mineral density (BMD) were measured on the same foot with a Walker Sonix UBA 575(+) and single X-ray absorptiometry. Hip and spine BMD were determined with a Hologic QDR-1000 densitometer using dual-energy X-ray absorptiometry. AHSG polymorphism was not significantly related to hip, lumbar spine, or calcaneal BMD. Compared with the homozygous AHSG*2 women, calcaneal BUA was 13% lower in heterozygous (P < 0.05) and 16% lower in homozygous AHSG*1 women (P < 0.05). This relationship persisted after controlling for age, weight, height, walks for exercise, and calcaneal BMD. Current and self-reported height were also lowest in homozygous AHSG*1 women, intermediate in heterozygous women, and highest among homozygous AHSG*2 subjects. These results suggest that the AHSG polymorphism may contribute to the genetic influence on calcaneal BUA and stature. [ABSTRACT FROM AUTHOR]

Calcaneal broadband ultrasound attenuation (BUA) is an independent predictor of hip and vertebral fractures. BUA is under genetic control, but the specific genes contributing to BUA are not well defined. We examined the relationship between genetic variation in α2HS-glycoprotein ( AHSG), an abundant noncollagenous protein of bone matrix, and calcaneal BUA. Genetic polymorphism in AHSG was determined in 222 Caucasian women (age 66–92) enrolled in the Pittsburgh Study of Osteoporotic Fractures clinical center by isoelectric focusing of serum samples. Calcaneal BUA and bone mineral density (BMD) were measured on the same foot with a Walker Sonix UBA 575+ and single X-ray absorptiometry. Hip and spine BMD were determined with a Hologic QDR-1000 densitometer using dual-energy X-ray absorptiometry. AHSG polymorphism was not significantly related to hip, lumbar spine, or calcaneal BMD. Compared with the homozygous AHSG*2 women, calcaneal BUA was 13% lower in heterozygous ( P < 0.05) and 16% lower in homozygous AHSG*1 women ( P < 0.05). This relationship persisted after controlling for age, weight, height, walks for exercise, and calcaneal BMD. Current and self-reported height were also lowest in homozygous AHSG*1 women, intermediate in heterozygous women, and highest among homozygous AHSG*2 subjects. These results suggest that the AHSG polymorphism may contribute to the genetic influence on calcaneal BUA and stature. [ABSTRACT FROM AUTHOR]

Objectives: The genetic aetiology of osteoarthritis has not yet been elucidated. To enable a well-powered genome-wide association study (GWAS) for osteoarthritis, the authors have formed the arcOGEN Consortium, a UK-wide collaborative effort aiming to scan genome-wide over 7500 osteoarthritis cases in a two-stage genome-wide association scan. Here the authors report the findings of the stage 1 interim analysis. Methods: The authors have performed a genome-wide association scan for knee and hip osteoarthritis in 3177 cases and 4894 population-based controls from the UK. Replication of promising signals was carried out in silico in five further scans (44 449 individuals), and de novo in 14 534 independent samples, all of European descent. Results: None of the association signals the authors identified reach genome-wide levels of statistical significance, therefore stressing the need for corroboration in sample sets of a larger size. Application of analytical approaches to examine the allelic architecture of disease to the stage 1 genome-wide association scan data suggests that osteoarthritis is a highly polygenic disease with multiple risk variants conferring small effects. Conclusions: Identifying loci conferring susceptibility to osteoarthritis will require large-scale sample sizes and well-defined phenotypes to minimise heterogeneity.