Publications by authors named "Eric Orwoll"

320 Publications

CT muscle density, D3Cr muscle mass and body fat associations with physical performance, mobility outcomes and mortality risk in older men.

J Gerontol A Biol Sci Med Sci 2021 Sep 16. Epub 2021 Sep 16.

California Pacific Medical Center Research Institute, San Francisco, CA.

Background: Muscle mass declines with age, while body adiposity increases. Sarcopenic obesity has been proposed to be particularly deleterious. However, previous methods for estimating muscle mass have been inadequate, and the relative contributions of total body fat vs. muscle fat to adverse outcomes have been unclear.

Methods: In a large cohort of older men (N= 1017), we measured muscle mass (D3 creatine dilution), muscle density (high resolution peripheral computed tomography in the diaphyseal tibia) as a proxy of muscle fat, and total body fat (dual energy x-ray absorptiometry). We examined their associations with physical performance (walking speed, grip strength, chair stand time), the risk of mobility outcomes (mobility limitations, mobility disability), and the risk of death over ~5 years.

Results: In combined models, lower muscle mass and muscle density were independently associated with worse physical performance and the risk of adverse outcomes, while total body fat was minimally related to physical performance and not related to mobility outcomes or mortality. For example, the relative risks for mortality per 1 standardized unit increase in muscle density, muscle mass, and total body fat were 0.84 (95% CI: 0.74, 0.70), 0.70 (0.57, 0.86), and 0.90 (0.64, 1.25), respectively.

Conclusions: Muscle mass and muscle density were associated with physical performance and adverse outcomes, and had independent, additive effects. There was little additional contribution of total body fat.
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http://dx.doi.org/10.1093/gerona/glab266DOI Listing
September 2021

What Cut-Point in Gait Speed Best Discriminates Community-Dwelling Older Adults With Mobility Complaints From Those Without? A Pooled Analysis From the Sarcopenia Definitions and Outcomes Consortium.

J Gerontol A Biol Sci Med Sci 2021 Sep;76(10):e321-e327

University of Florida, Gainesville, USA.

Background: Cut-points to define slow walking speed have largely been derived from expert opinion.

Methods: Study participants (13 589 men and 5043 women aged ≥65years) had walking speed (m/s) measured over 4-6 m (mean ± SD: 1.20 ± 0.27 m/s in men and 0.94 ± 0.24 m/s in women.) Mobility limitation was defined as any self-reported difficulty with walking approximately 1/4 mile (prevalence: 12.6% men, 26.4% women). Sex-stratified classification and regression tree (CART) models with 10-fold cross-validation identified walking speed cut-points that optimally discriminated those who reported mobility limitation from those who did not.

Results: Among 5043 women, CART analysis identified 2 cut-points, classifying 4144 (82.2%) with walking speed ≥0.75 m/s, which we labeled as "fast"; 478 (9.5%) as "intermediate" (walking speed ≥0.62 m/s but <0.75 m/s); and 421 (8.3%) as "slow" (walking speed <0.62 m/s). Among 13 589 men, CART analysis identified 3 cut-points, classifying 10 001 (73.6%) with walking speed ≥1.00 m/s ("very fast"); 2901 (21.3%) as "fast" (walking speed ≥0.74 m/s but <1.00 m/s); 497 (3.7%) as "intermediate" (walking speed ≥0.57 m/s but <0.74 m/s); and 190 (1.4%) as "slow" (walking speed <0.57 m/s). Prevalence of self-reported mobility limitation was lowest in the "fast" or "very fast" (11% for men and 19% for women) and highest in the "slow" (60.5% in men and 71.0% in women). Rounding the 2 slower cut-points to 0.60 m/s and 0.75 m/s reclassified very few participants.

Conclusions: Cut-points in walking speed of approximately 0.60 m/s and 0.75 m/s discriminate those with self-reported mobility limitation from those without.
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http://dx.doi.org/10.1093/gerona/glab183DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8436986PMC
September 2021

Sarcopenia Definitions as Predictors of Fracture Risk Independent of FRAX , Falls, and BMD in the Osteoporotic Fractures in Men (MrOS) Study: A Meta-Analysis.

J Bone Miner Res 2021 07 8;36(7):1235-1244. Epub 2021 Apr 8.

Centre for Metabolic Bone Diseases, University of Sheffield, Sheffield, UK.

Dual-energy X-ray absorptiometry (DXA)-derived appendicular lean mass/height (ALM/ht ) is the most commonly used estimate of muscle mass in the assessment of sarcopenia, but its predictive value for fracture is substantially attenuated by femoral neck (fn) bone mineral density (BMD). We investigated predictive value of 11 sarcopenia definitions for incident fracture, independent of fnBMD, fracture risk assessment tool (FRAX ) probability, and prior falls, using an extension of Poisson regression in US, Sweden, and Hong Kong Osteoporois Fractures in Men Study (MrOS) cohorts. Definitions tested were those of Baumgartner and Delmonico (ALM/ht only), Morley, the International Working Group on Sarcopenia, European Working Group on Sarcopenia in Older People (EWGSOP1 and 2), Asian Working Group on Sarcopenia, Foundation for the National Institutes of Health (FNIH) 1 and 2 (using ALM/body mass index [BMI], incorporating muscle strength and/or physical performance measures plus ALM/ht ), and Sarcopenia Definitions and Outcomes Consortium (gait speed and grip strength). Associations were adjusted for age and time since baseline and reported as hazard ratio (HR) for first incident fracture, here major osteoporotic fracture (MOF; clinical vertebral, hip, distal forearm, proximal humerus). Further analyses adjusted additionally for FRAX-MOF probability (n = 7531; calculated ± fnBMD), prior falls (y/n), or fnBMD T-score. Results were synthesized by meta-analysis. In 5660 men in USA, 2764 Sweden and 1987 Hong Kong (mean ages 73.5, 75.4, and 72.4 years, respectively), sarcopenia prevalence ranged from 0.5% to 35%. Sarcopenia status, by all definitions except those of FNIH, was associated with incident MOF (HR = 1.39 to 2.07). Associations were robust to adjustment for prior falls or FRAX probability (without fnBMD); adjustment for fnBMD T-score attenuated associations. EWGSOP2 severe sarcopenia (incorporating chair stand time, gait speed, and grip strength plus ALM) was most predictive, albeit at low prevalence, and appeared only modestly influenced by inclusion of fnBMD. In conclusion, the predictive value for fracture of sarcopenia definitions based on ALM is reduced by adjustment for fnBMD but strengthened by additional inclusion of physical performance measures. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).
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http://dx.doi.org/10.1002/jbmr.4293DOI Listing
July 2021

Sex-specific 25-hydroxyvitamin D threshold concentrations for functional outcomes in older adults: PRoject on Optimal VItamin D in Older adults (PROVIDO).

Am J Clin Nutr 2021 07;114(1):16-28

California Pacific Medical Center Research Institute, San Francisco, CA, USA.

Background: Threshold serum 25-hydroxyvitamin D [25(OH)D] concentrations for extraskeletal outcomes are uncertain and could differ from recommendations (20-30 ng/mL) for skeletal health.

Objectives: We aimed to identify and validate sex-specific threshold 25(OH)D concentrations for older adults' physical function.

Methods: Using 5 large prospective, population-based studies-Age, Gene/Environment Susceptibility-Reykjavik (n = 4858, Iceland); Health, Aging, and Body Composition (n = 2494, United States); Invecchiare in Chianti (n = 873, Italy); Osteoporotic Fractures in Men (n = 2301, United States); and Study of Osteoporotic Fractures (n = 5862, United States)-we assessed 16,388 community-dwelling adults (10,376 women, 6012 men) aged ≥65 y. We analyzed 25(OH)D concentrations with the primary outcome (incident slow gait: women <0.8 m/s; men <0.825 m/s) and secondary outcomes (gait speed, incident self-reported mobility, and stair climb impairment) at median 3.0-y follow-up. We identified sex-specific 25(OH)D thresholds that best discriminated incident slow gait using machine learning in training data (2/3 cohort-stratified random sample) and validated using the remaining (validation) data and secondary outcomes.

Results: Mean age in the cohorts ranged from 74.4 to 76.5 y in women and from 73.3 to 76.6 y in men. Overall, 1112/6123 women (18.2%) and 494/3937 men (12.5%) experienced incident slow gait, 1098/7011 women (15.7%) and 474/3962 men (12.0%) experienced incident mobility impairment, and 1044/6941 women (15.0%) and 432/3993 men (10.8%) experienced incident stair climb impairment. Slow gait was best discriminated by 25(OH)D <24.0 ng/mL compared with 25(OH)D ≥24.0 ng/mL in women (RR: 1.29; 95% CI: 1.10, 1.50) and 25(OH)D <21.0 ng/mL compared with 25(OH)D ≥21.0 ng/mL in men (RR: 1.43; 95% CI: 1.01, 2.02). Most associations between 25(OH)D and secondary outcomes were modest; estimates were similar between validation and training datasets.

Conclusions: Empirically identified and validated sex-specific threshold 25(OH)D concentrations for physical function for older adults, 24.0 ng/mL for women and 21.0 ng/mL for men, may inform candidate reference concentrations or the design of vitamin D intervention trials.
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http://dx.doi.org/10.1093/ajcn/nqab025DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8246604PMC
July 2021

Gut microbiome pattern reflects healthy ageing and predicts survival in humans.

Nat Metab 2021 02 18;3(2):274-286. Epub 2021 Feb 18.

Institute for Systems Biology, Seattle, WA, USA.

The gut microbiome has important effects on human health, yet its importance in human ageing remains unclear. In the present study, we demonstrate that, starting in mid-to-late adulthood, gut microbiomes become increasingly unique to individuals with age. We leverage three independent cohorts comprising over 9,000 individuals and find that compositional uniqueness is strongly associated with microbially produced amino acid derivatives circulating in the bloodstream. In older age (over ~80 years), healthy individuals show continued microbial drift towards a unique compositional state, whereas this drift is absent in less healthy individuals. The identified microbiome pattern of healthy ageing is characterized by a depletion of core genera found across most humans, primarily Bacteroides. Retaining a high Bacteroides dominance into older age, or having a low gut microbiome uniqueness measure, predicts decreased survival in a 4-year follow-up. Our analysis identifies increasing compositional uniqueness of the gut microbiome as a component of healthy ageing, which is characterized by distinct microbial metabolic outputs in the blood.
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http://dx.doi.org/10.1038/s42255-021-00348-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8169080PMC
February 2021

Improved prediction of fracture risk leveraging a genome-wide polygenic risk score.

Genome Med 2021 02 3;13(1):16. Epub 2021 Feb 3.

Centre for Clinical Epidemiology, Lady Davis Institute for Medical Research, Jewish General Hospital, Room H-413, 3755 Chemin de la Côte-Sainte-Catherine, Montreal, Quebec, H3T 1E2, Canada.

Background: Accurately quantifying the risk of osteoporotic fracture is important for directing appropriate clinical interventions. While skeletal measures such as heel quantitative speed of sound (SOS) and dual-energy X-ray absorptiometry bone mineral density are able to predict the risk of osteoporotic fracture, the utility of such measurements is subject to the availability of equipment and human resources. Using data from 341,449 individuals of white British ancestry, we previously developed a genome-wide polygenic risk score (PRS), called gSOS, that captured 25.0% of the total variance in SOS. Here, we test whether gSOS can improve fracture risk prediction.

Methods: We examined the predictive power of gSOS in five genome-wide genotyped cohorts, including 90,172 individuals of European ancestry and 25,034 individuals of Asian ancestry. We calculated gSOS for each individual and tested for the association between gSOS and incident major osteoporotic fracture and hip fracture. We tested whether adding gSOS to the risk prediction models had added value over models using other commonly used clinical risk factors.

Results: A standard deviation decrease in gSOS was associated with an increased odds of incident major osteoporotic fracture in populations of European ancestry, with odds ratios ranging from 1.35 to 1.46 in four cohorts. It was also associated with a 1.26-fold (95% confidence interval (CI) 1.13-1.41) increased odds of incident major osteoporotic fracture in the Asian population. We demonstrated that gSOS was more predictive of incident major osteoporotic fracture (area under the receiver operating characteristic curve (AUROC) = 0.734; 95% CI 0.727-0.740) and incident hip fracture (AUROC = 0.798; 95% CI 0.791-0.805) than most traditional clinical risk factors, including prior fracture, use of corticosteroids, rheumatoid arthritis, and smoking. We also showed that adding gSOS to the Fracture Risk Assessment Tool (FRAX) could refine the risk prediction with a positive net reclassification index ranging from 0.024 to 0.072.

Conclusions: We generated and validated a PRS for SOS which was associated with the risk of fracture. This score was more strongly associated with the risk of fracture than many clinical risk factors and provided an improvement in risk prediction. gSOS should be explored as a tool to improve risk stratification to identify individuals at high risk of fracture.
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http://dx.doi.org/10.1186/s13073-021-00838-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7860212PMC
February 2021

Response to "Red Cell Distribution Width Is a Risk Factor for Hip Fracture in Elderly Men Without Anemia".

J Bone Miner Res 2021 06 28;36(6):1203. Epub 2021 Jan 28.

San Francisco Coordinating Center, California Pacific Medical Center Research Institute, San Francisco, CA, USA.

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http://dx.doi.org/10.1002/jbmr.4242DOI Listing
June 2021

Vitamin D metabolites and the gut microbiome in older men.

Nat Commun 2020 11 26;11(1):5997. Epub 2020 Nov 26.

Department of Medicine, University of California San Diego, La Jolla, CA, USA.

The vitamin D receptor is highly expressed in the gastrointestinal tract where it transacts gene expression. With current limited understanding of the interactions between the gut microbiome and vitamin D, we conduct a cross-sectional analysis of 567 older men quantifying serum vitamin D metabolites using LC-MSMS and defining stool sub-Operational Taxonomic Units from16S ribosomal RNA gene sequencing data. Faith's Phylogenetic Diversity and non-redundant covariate analyses reveal that the serum 1,25(OH)D level explains 5% of variance in α-diversity. In β-diversity analyses using unweighted UniFrac, 1,25(OH)D is the strongest factor assessed, explaining 2% of variance. Random forest analyses identify 12 taxa, 11 in the phylum Firmicutes, eight of which are positively associated with either 1,25(OH)D and/or the hormone-to-prohormone [1,25(OH)D/25(OH)D] "activation ratio." Men with higher levels of 1,25(OH)D and higher activation ratios, but not 25(OH)D itself, are more likely to possess butyrate producing bacteria that are associated with better gut microbial health.
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http://dx.doi.org/10.1038/s41467-020-19793-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7693238PMC
November 2020

Widespread disturbance in extracellular matrix collagen biomarker responses to teriparatide therapy in osteogenesis imperfecta.

Bone 2021 01 21;142:115703. Epub 2020 Oct 21.

Department of Medicine, Bone and Mineral Unit, Oregon Health & Science University, Portland, OR, United States of America.

Osteogenesis imperfecta (OI), a heritable disorder caused by abnormalities in synthesis or processing of type I collagen, is characterized by skeletal fragility. Type I collagen interacts with multiple components of the extracellular matrix (ECM) including other collagens types. Thus, alterations in structure or quantity may broadly affect ECM homeostasis. In fact, while OI is clinically categorized by severity of bone disease, patients can also present with extra-skeletal manifestations, including the pulmonary, muscle and cardiovascular systems. Parathyroid hormone (PTH) is a regulator of skeletal homeostasis but the receptor for PTH/PTH1R is expressed in a variety of other tissues. Given interactions between type I collagen with other collagens in the ECM and the potential for PTH action on tissues beyond the skeleton, we explored whether serum levels of non-type I collagens are altered in response to teriparatide (human parathyroid hormone 1-34). We measured biomarkers of collagens II, III, IV, V, and VI in serum from individuals with type I and types III/IV OI in response to an 18 month course of teriparatide or placebo. These results were compared to similar biomarker measures in postmenopausal (PM) women without OI treated with teriparatide. In type I OI, teriparatide therapy increased concentrations of biomarkers of collagens II, III, IV, V, and VI. In individuals with types III/IV OI these biomarker changes in response to teriparatide were blunted, as we previously reported with collagen I biomarkers during teriparatide therapy. In contrast to OI, in PM women there were no effects of teriparatide on the collagen biomarkers we assessed (II, V, and VI). These findings suggest that in OI teriparatide therapy has abnormal effects on the homeostasis of many ECM collagens likely derived from skeletal as well as extra-skeletal tissues.
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http://dx.doi.org/10.1016/j.bone.2020.115703DOI Listing
January 2021

Proteomic assessment of serum biomarkers of longevity in older men.

Aging Cell 2020 11 20;19(11):e13253. Epub 2020 Oct 20.

Oregon Health & Science University, Portland, OR, USA.

The biological bases of longevity are not well understood, and there are limited biomarkers for the prediction of long life. We used a high-throughput, discovery-based proteomics approach to identify serum peptides and proteins that were associated with the attainment of longevity in a longitudinal study of community-dwelling men age ≥65 years. Baseline serum in 1196 men were analyzed using liquid chromatography-ion mobility-mass spectrometry, and lifespan was determined during ~12 years of follow-up. Men who achieved longevity (≥90% expected survival) were compared to those who died earlier. Rigorous statistical methods that controlled for false positivity were utilized to identify 25 proteins that were associated with longevity. All these proteins were in lower abundance in long-lived men and included a variety involved in inflammation or complement activation. Lower levels of longevity-associated proteins were also associated with better health status, but as time to death shortened, levels of these proteins increased. Pathway analyses implicated a number of compounds as important upstream regulators of the proteins and implicated shared networks that underlie the observed associations with longevity. Overall, these results suggest that complex pathways, prominently including inflammation, are linked to the likelihood of attaining longevity. This work may serve to identify novel biomarkers for longevity and to understand the biology underlying lifespan.
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http://dx.doi.org/10.1111/acel.13253DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7681066PMC
November 2020

Serum Testosterone is Inversely and Sex Hormone-binding Globulin is Directly Associated with All-cause Mortality in Men.

J Clin Endocrinol Metab 2021 01;106(2):e625-e637

School of Population and Global Health, University of Western Australia, Perth, Australia.

Context: Serum testosterone concentrations decline with age, while serum sex hormone-binding globulin (SHBG) concentrations increase.

Objective: To analyze associations of baseline serum testosterone and SHBG concentrations, and calculated free testosterone (cFT) values, with all-cause and cause-specific mortality in men.

Design, Setting, And Participants: The UK Biobank prospective cohort study of community-dwelling men aged 40-69 years old, followed for 11 years.

Main Outcome Measures: All-cause, atherosclerotic cardiovascular disease (CVD) and cancer-related mortality. Cox proportional hazards regression was performed, adjusting for age, waist circumference, medical conditions, and other covariates. Models for testosterone included SHBG and vice versa.

Results: In a complete case analysis of 149 436 men with 10 053 deaths (1925 CVD and 4927 cancer-related), men with lower testosterone had a higher mortality rate from any cause (lowest vs highest quintile, Q1 vs Q5, fully-adjusted hazard ratio [HR] = 1.14, 95% confidence interval [CI] = 1.06-1.22, overall trend P < 0.001), and cancer (HR = 1.20, CI = 1.09-1.33, P < 0.001), with no association for CVD deaths. Similar results were seen for cFT. Men with lower SHBG had a lower mortality rate from any cause (Q1 vs Q5, HR = 0.68, CI = 0.63-0.73, P < 0.001), CVD (HR = 0.70, CI = 0.59-0.83, P < 0.001), and cancer (HR = 0.80, CI = 0.72-0.89, P < 0.001). A multiply imputed dataset (N = 208 425, 15 914 deaths, 3128 CVD-related and 7468 cancer-related) and analysis excluding deaths within the first 2 years (9261, 1734, and 4534 events) yielded similar results.

Conclusions: Lower serum testosterone is independently associated with higher all-cause and cancer-related, but not CVD-related, mortality in middle-aged to older men. Lower SHBG is independently associated with lower all-cause, CVD-related, and cancer-related mortality. Confirmation and determination of causality requires mechanistic studies and prospective trials.
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http://dx.doi.org/10.1210/clinem/dgaa743DOI Listing
January 2021

Sociodemographic, lifestyle and medical influences on serum testosterone and sex hormone-binding globulin in men from UK Biobank.

Clin Endocrinol (Oxf) 2021 02 10;94(2):290-302. Epub 2020 Oct 10.

School of Population and Global Health, University of Western Australia, Perth, WA, Australia.

Objective: Serum testosterone concentrations are affected by factors unrelated to hypothalamo-pituitary-testicular axis pathology. We evaluated the impact of sociodemographic, lifestyle and medical factors, on serum testosterone and sex hormone-binding globulin (SHBG) in men aged 40-69 years.

Design: Cross-sectional analysis of 208,677 community-dwelling men from the UK Biobank.

Measurements: We analysed associations of different factors with serum testosterone and SHBG (immunoassays) and calculated free testosterone (cFT), using smoothed centile plots, linear mixed models and effect size estimates.

Results: Median (interquartile range) for serum testosterone was 11.6 (9.4-14.1) nmol/L, SHBG 36.9 (27.9-48.1) nmol/L and cFT 213 (178-255) pmol/L. Age and BMI were inversely associated with testosterone and cFT, while SHBG was associated with age and inversely with BMI (all P < .001). Living with a partner, (South) Asian ethnicity, never or previous smoker and some medical conditions were associated with lower testosterone. Poultry or fish eater, and higher physical activity were associated with higher testosterone (all P < .001). Testosterone was lowered by ~0.5 nmol/L across ages, ~1.5 nmol/L for BMI 30 vs 25 kg/m , ~2 nmol/L for (South) Asian ethnicity, living with partner, college/university qualifications, low red meat eater, insufficient physical activity and 0.3-1.0 nmol/L with cardiovascular disease or diabetes. Different combinations of these factors varied serum testosterone by ~4 nmol/L, SHBG by ~30 nmol/L and cFT by ~60 pmol/L.

Conclusions: The identified modifiable risk factors support lifestyle-based interventions in men with low testosterone concentrations. Considering sociodemographic, lifestyle and medical factors facilitates more personalized interpretation of testosterone testing results with respect to existing reference ranges.
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http://dx.doi.org/10.1111/cen.14342DOI Listing
February 2021

Association Between Variation in Red Cell Size and Multiple Aging-Related Outcomes.

J Gerontol A Biol Sci Med Sci 2021 Jun;76(7):1288-1294

San Francisco Coordinating Center, California.

Background: We tested whether greater variation in red blood cell size, measured by red cell distribution width (RDW), may predict aging-related degenerative conditions and therefore, serve as a marker of biological aging.

Methods: Three thousand six hundred and thirty-five community-dwelling older men were enrolled in the prospective Osteoporotic Fractures in Men Study. RDW was categorized into 4 groups (≤13.0%, 13.1%-14.0%, 14.1%-15.0%, and ≥15.1%). Functional limitations, frailty, strength, physical performance, and cognitive function were measured at baseline and 7.4 years later. Falls were recorded in the year after baseline; hospitalizations were obtained for 2 years after baseline. Mortality was assessed during a mean of 8.3 years of follow-up.

Results: Participants with greater variability in red cell size were weaker, walked more slowly, and had a worse cognitive function. They were more likely to have functional limitations (35.2% in the highest RDW category vs 16.0% in the lowest, p < .001) and frailty (30.3% vs 11.3%, p < .001). Those with greater variability in red cell size were more likely to develop new functional limitations and to become frail. The risk of having 2 or more falls was also greater (highest 19.2% vs lowest 10.3%, p < .001). The risk of hospitalization was higher in those with the highest variability (odds ratio [95% confidence interval], 1.8 [1.3-2.5]) compared with the lowest. Variability in red cell size was related to total and cause-specific mortality.

Conclusion: Greater variability in red cell size is associated with diverse aging-related outcomes, suggesting that it may have potential value as a marker for biological aging.
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http://dx.doi.org/10.1093/gerona/glaa217DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8202142PMC
June 2021

Development of a polygenic risk score to improve screening for fracture risk: A genetic risk prediction study.

PLoS Med 2020 07 2;17(7):e1003152. Epub 2020 Jul 2.

Centre for Clinical Epidemiology, Department of Medicine, Lady Davis Institute, Jewish General Hospital, McGill University, Montréal, Québec, Canada.

Background: Since screening programs identify only a small proportion of the population as eligible for an intervention, genomic prediction of heritable risk factors could decrease the number needing to be screened by removing individuals at low genetic risk. We therefore tested whether a polygenic risk score for heel quantitative ultrasound speed of sound (SOS)-a heritable risk factor for osteoporotic fracture-can identify low-risk individuals who can safely be excluded from a fracture risk screening program.

Methods And Findings: A polygenic risk score for SOS was trained and selected in 2 separate subsets of UK Biobank (comprising 341,449 and 5,335 individuals). The top-performing prediction model was termed "gSOS", and its utility in fracture risk screening was tested in 5 validation cohorts using the National Osteoporosis Guideline Group clinical guidelines (N = 10,522 eligible participants). All individuals were genome-wide genotyped and had measured fracture risk factors. Across the 5 cohorts, the average age ranged from 57 to 75 years, and 54% of studied individuals were women. The main outcomes were the sensitivity and specificity to correctly identify individuals requiring treatment with and without genetic prescreening. The reference standard was a bone mineral density (BMD)-based Fracture Risk Assessment Tool (FRAX) score. The secondary outcomes were the proportions of the screened population requiring clinical-risk-factor-based FRAX (CRF-FRAX) screening and BMD-based FRAX (BMD-FRAX) screening. gSOS was strongly correlated with measured SOS (r2 = 23.2%, 95% CI 22.7% to 23.7%). Without genetic prescreening, guideline recommendations achieved a sensitivity and specificity for correct treatment assignment of 99.6% and 97.1%, respectively, in the validation cohorts. However, 81% of the population required CRF-FRAX tests, and 37% required BMD-FRAX tests to achieve this accuracy. Using gSOS in prescreening and limiting further assessment to those with a low gSOS resulted in small changes to the sensitivity and specificity (93.4% and 98.5%, respectively), but the proportions of individuals requiring CRF-FRAX tests and BMD-FRAX tests were reduced by 37% and 41%, respectively. Study limitations include a reliance on cohorts of predominantly European ethnicity and use of a proxy of fracture risk.

Conclusions: Our results suggest that the use of a polygenic risk score in fracture risk screening could decrease the number of individuals requiring screening tests, including BMD measurement, while maintaining a high sensitivity and specificity to identify individuals who should be recommended an intervention.
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http://dx.doi.org/10.1371/journal.pmed.1003152DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7331983PMC
July 2020

Muscle Mass Assessed by the D3-Creatine Dilution Method and Incident Self-reported Disability and Mortality in a Prospective Observational Study of Community-Dwelling Older Men.

J Gerontol A Biol Sci Med Sci 2021 01;76(1):123-130

Department of Nutrition Sciences, University of California, Berkeley.

Background: Whether low muscle mass is a risk factor for disability and mortality is unclear. Associations between approximations of muscle mass (including lean mass from dual-energy x-ray absorptiometry [DXA]), and these outcomes are inconsistent.

Methods: Muscle mass measured by deuterated creatine (D3Cr) dilution and appendicular lean mass (ALM, by DXA) were assessed at the Year 14 Visit (2014-2016) of the prospective Osteoporotic Fractures in Men study (N = 1,425, age 77-101 years). Disability in activities of daily living (ADLs), instrumental ADLs, and mobility tasks was self-reported at the Year 14 visit and 2.2 years later; deaths were centrally adjudicated over 3.3 years. Relative risks and 95% confidence intervals (CI) were estimated per standard deviation decrement with negative binomial, logistic regression, or proportional hazards models.

Results: In age- and clinical center-adjusted models, the relative risks per decrement in D3Cr muscle mass/wgt was 1.9 (95% CI: 1.2, 3.1) for incident self-reported ADL disability; 1.5 (95% CI: 1.3, 1.9) for instrumental ADL disability; and 1.8 (95% CI: 1.5, 2.2) for mobility disability. In age-, clinical center-, and weight-adjusted models, the relative risks per decrement in D3Cr muscle mass was 1.8 (95% CI: 1.5, 2.2) for all-cause mortality. In contrast, lower DXA ALM was not associated with any outcome. Associations of D3Cr muscle mass with these outcomes were slightly attenuated after adjustment for confounding factors and the potentially mediating effects of strength and physical performance.

Conclusions: Low muscle mass as measured by D3Cr dilution is a novel risk factor for clinically meaningful outcomes in older men.
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http://dx.doi.org/10.1093/gerona/glaa111DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7756711PMC
January 2021

The Importance of Muscle Versus Fat Mass in Sarcopenic Obesity: A Re-evaluation Using D3-Creatine Muscle Mass Versus DXA Lean Mass Measurements.

J Gerontol A Biol Sci Med Sci 2020 06;75(7):1362-1368

Research Institute, California Pacific Medical Center, San Francisco.

Background: The combination of sarcopenia and obesity has been associated with physical impairment in older people. However, previous research has relied on assessments of lean mass as a surrogate for muscle mass. We postulate that inaccurate measures of muscle mass may have obscured the role of obesity in sarcopenia and related outcomes. Our aim was to clarify the interactions of muscle and fat with physical performance and adverse outcomes using an accurate measure of muscle mass.

Methods: In a longitudinal study of >1,300 older men (mean age 84 years), we compared a direct measurement of muscle mass (D3 creatine dilution; D3Cr) with an approximation of muscle mass (appendicular lean mass [ALM] by dual-energy x-ray absorptiometry [DXA]) and their associations with measures of physical performance (gait speed, chair stand time) and adverse outcomes (incident injurious falls and mobility problems). We measured percent fat mass by DXA.

Results: Low D3Cr muscle mass was strongly associated with decreased performance and increased risk of adverse outcomes. Increased fat mass had little association after accounting for D3Cr muscle mass. In contrast, DXA ALM was minimally associated with performance or adverse outcomes, and fatness remained associated with both outcomes after accounting for DXA ALM.

Conclusions: When an accurate assessment of muscle mass (rather than lean mass) is used, reduced muscle mass is highly associated with important outcomes and the negative effects of adiposity are minimal, suggesting that obesity has little relevance for the understanding of important adverse health outcomes of sarcopenia in older men.
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http://dx.doi.org/10.1093/gerona/glaa064DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7302180PMC
June 2020

Androgens In Men Study (AIMS): protocol for meta-analyses of individual participant data investigating associations of androgens with health outcomes in men.

BMJ Open 2020 05 11;10(5):e034777. Epub 2020 May 11.

School of Population and Global Health, University of Western Australia, Perth, Western Australia, Australia.

Introduction: This study aims to clarify the role(s) of endogenous sex hormones to influence health outcomes in men, specifically to define the associations of plasma testosterone with incidence of cardiovascular events, cancer, dementia and mortality risk, and to identify factors predicting testosterone concentrations. Data will be accrued from at least three Australian, two European and four North American population-based cohorts involving approximately 20 000 men.

Methods And Analysis: Eligible studies include prospective cohort studies with baseline testosterone concentrations measured using mass spectrometry and 5 years of follow-up data on incident cardiovascular events, mortality, cancer diagnoses or deaths, new-onset dementia or decline in cognitive function recorded. Data for men, who were not taking androgens or drugs suppressing testosterone production, metabolism or action; and had no prior orchidectomy, are eligible. Systematic literature searches were conducted from 14 June 2019 to 31 December 2019, with no date range set for searches. Aggregate level data will be sought where individual participant data (IPD) are not available. One-stage IPD random-effects meta-analyses will be performed, using linear mixed models, generalised linear mixed models and either stratified or frailty-augmented Cox regression models. Heterogeneity in estimates from different studies will be quantified and bias investigated using funnel plots. Effect size estimates will be presented in forest plots and non-negligible heterogeneity and bias investigated using subgroup or meta-regression analyses.

Ethics And Dissemination: Ethics approvals obtained for each of the participating cohorts state that participants have consented to have their data collected and used for research purposes. The Androgens In Men Study has been assessed as exempt from ethics review by the Human Ethics office at the University of Western Australia (file reference number RA/4/20/5014). Each of the component studies had obtained ethics approvals; please refer to respective component studies for details. Research findings will be disseminated to the scientific and broader community via the publication of four research articles, with each involving a separate set of IPD meta-analyses (articles will investigate different, distinct outcomes), at scientific conferences and meetings of relevant professional societies. Collaborating cohort studies will disseminate findings to study participants and local communities.

Prospero Registration Number: CRD42019139668.
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http://dx.doi.org/10.1136/bmjopen-2019-034777DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7239545PMC
May 2020

Walking Speed and Muscle Mass Estimated by the D-Creatine Dilution Method Are Important Components of Sarcopenia Associated With Incident Mobility Disability in Older Men: A Classification and Regression Tree Analysis.

J Am Med Dir Assoc 2020 12 4;21(12):1997-2002.e1. Epub 2020 May 4.

Research Institute, California Pacific Medical Center, San Francisco, CA, USA; Department of Epidemiology and Biostatistics, University of California, San Francisco, CA, USA. Electronic address:

Objectives: It is unknown whether muscle mass measured by the D-creatine dilution method is a superior predictor of incident mobility disability than traditional components of sarcopenia definitions (including grip strength, walking speed, appendicular lean mass). The objective of this study was to determine the relative importance of strength; physical performance; and lean, fat, and muscle mass in predicting incident mobility disability in older men.

Design: Longitudinal cohort study of participants in the Osteoporotic Fractures in Men (MrOS) study.

Setting And Participants: Muscle mass was assessed by D-creatine dilution in 1098 men (aged 83.7 ± 3.7 years). Participants also completed anthropomorphic measures, 6-m walking speed (m/s), grip strength (kg), chair stands (seconds), and dual x-ray absorptiometry appendicular lean mass (ALM), and total body fat percentage. Men self-reported incident mobility disability defined by the development of an inability to complete at least one of walking 2-3 blocks, climbing 10 steps, or carrying 10 lb over 2.2 ± 0.3 years.

Methods: Classification and regression tree analysis was conducted to determine relative variable importance and algorithm cutpoints for predicting incident mobility disability. Given the proximity of walking speed with the primary outcome (mobility disability), analyses were conducted with and without walking speed.

Results: Walking speed followed by DCr muscle mass/weight were the most important variables (variable importance: 53% and 12%, respectively) in the prediction of self-reported incident mobility disability. DCr muscle mass was the most important variable in predicting incident mobility disability when walking speed was excluded, followed by chair stands (variable importance: 35% and 33%, respectively). Body fat percentage, ALM, and grip strength were not selected as nodes in either analysis and had low or negligible variable importance.

Conclusions And Implications: This study has provided valuable insights into the importance of different variables in predicting incident mobility disability in older men. Muscle mass by DCr may be a key tool for predicting the risk of negative outcomes in older adults in the future, particularly in post-acute and long-term care settings.
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http://dx.doi.org/10.1016/j.jamda.2020.03.017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8057698PMC
December 2020

Individual and joint trajectories of change in bone, lean mass and physical performance in older men.

BMC Geriatr 2020 05 5;20(1):161. Epub 2020 May 5.

Oregon Health and Science University, Portland, OR, USA.

Background: Declines in bone, muscle and physical performance are associated with adverse health outcomes in older adults. However, few studies have described concurrent age-related patterns of change in these factors. The purpose of this study was to characterize change in four properties of muscle, physical performance, and bone in a prospective cohort study of older men.

Methods: Using repeated longitudinal data from up to four visits across 6.9 years from up to 4681 men (mean age at baseline 72.7 yrs. ±5.3) participating in the Osteoporotic Fractures in Men (MrOS) Study, we used group-based trajectory models (PROC TRAJ in SAS) to identify age-related patterns of change in four properties of muscle, physical performance, and bone: total hip bone mineral (BMD) density (g/m) and appendicular lean mass/ht (kg/m), by DXA; grip strength (kg), by hand dynamometry; and walking speed (m/s), by usual walking pace over 6 m. We also described joint trajectories in all pair-wise combinations of these measures. Mean posterior probabilities of placement in each trajectory (or joint membership in latent groups) were used to assess internal reliability of the model. The number of trajectories for each individual factor was limited to three, to ensure that the pair-wise determination of joint trajectories would yield a tractable number of groups as well as model fit considerations.

Results: The patterns of change identified were generally similar for all measures, with three district groups declining over time at roughly similar rates; joint trajectories revealed similar patterns with no cross-over or convergence between groups. Mean posterior probabilities for all trajectories were similar and consistently above 0.8 indicating reasonable model fit to the data.

Conclusions: Our description of trajectories of change with age in bone mineral density, grip strength, walking speed and appendicular lean mass found that groups identified by these methods appeared to have little crossover or convergence of change with age, even when considering joint trajectories of change in these factors.
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http://dx.doi.org/10.1186/s12877-020-01560-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7201689PMC
May 2020

Sleep Restriction With Circadian Disruption Negatively Alter Bone Turnover Markers in Women.

J Clin Endocrinol Metab 2020 07;105(7)

Division of Sleep Medicine, Harvard Medical School, Boston, Massachusetts, US.

Purpose: The purpose of this work is to determine whether an uncoupling of bone turnover markers (BTMs) occurs in women exposed to the combination of sleep restriction with circadian disruption (SRCD), as previously reported in men.

Methods: Four bone biomarkers (N-terminal propeptide of type I procollagen [P1NP] and osteocalcin = bone formation; C-telopeptide [CTX] = bone resorption; sclerostin = bone formation inhibitor) were measured in bihourly samples over 24 hours at baseline and after approximately 3 weeks of sleep restriction (~5.6 hours of sleep/24 hours) with concurrent circadian disruption (SRCD, recurring 28-hour "day" in dim light). Maximum likelihood estimation in a repeated-measures model was used to assess the effects of SRCD and age on bone biomarkers.

Results: Five women were young (22 ± 2.8 years) and four were older (58 ± 1.8 years). Baseline bone biomarker levels did not differ by age (all P ≥ .07). Bone formation markers were lower after SRCD (estimate ± SEE, ΔP1NP = -9.5 ± 2.8 μg/L, P = .01; Δosteocalcin = -2.3 ± 0.9 ng/mL, P = .04). The P1NP decline was greater in young women (ΔP1NP = -12.9 ± 3.7 μg/L, P = .01). After SRCD, CTX was significantly higher in young women (0.182 ± 0.069 ng/mL, P = .04) but did not change in older women.

Conclusions: These pilot data are similar to previous findings in men and suggest that SRCD negatively altered bone metabolism in women by decreasing markers of bone formation and, in young women, increasing a marker of bone resorption. If sustained, this pattern of BTM uncoupling may lead to bone loss and lower bone mineral density.
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http://dx.doi.org/10.1210/clinem/dgaa232DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7448297PMC
July 2020

Endogenous Testosterone Levels and the Risk of Incident Cardiovascular Events in Elderly Men: The MrOS Prospective Study.

J Endocr Soc 2020 May 24;4(5):bvaa038. Epub 2020 Mar 24.

Division of General Internal Medicine, University of California at San Francisco, San Francisco, California.

Context: Observational studies show discordant links between endogenous testosterone levels and cardiovascular diseases (CVD).

Objective: We assessed whether sex hormones and sex hormone-binding globulin (SHBG) are associated with CVD in community-dwelling elderly men.

Design Setting And Participants: Prospective study of incident CVD among 552 men ≥ 65 years in the MrOS Sleep Study without prevalent CVD and no testosterone therapy at baseline.

Outcomes: Fasting serum levels of total testosterone and estradiol were measured using liquid chromatography-mass spectrometry, and SHBG by chemiluminescent substrate. The association of sex hormones and SHBG with incident coronary heart disease (CHD), cerebrovascular (stroke and transient ischemic attack) and peripheral arterial disease (PAD) events were assessed by quartile and per SD increase in proportional hazards models.

Results: After 7.4 years, 137 men (24.8%) had at least 1 CVD event: 90 CHD, 45 cerebrovascular and 26 PAD. The risk of incident CVD events was not associated with quartiles of baseline sex hormones or SHBG (all  ≥ 0.16). For +1 SD in total testosterone, the multivariate-adjusted hazard ratio was 1.04 (95% CI, 0.80-1.34) for CHD, 0.86 (0.60-1.25) for cerebrovascular, and 0.81 (0.52-1.26) for PAD events. When analyzed as continuous variables or comparing highest to low quartile, levels of bioavailable testosterone, total estradiol, testosterone/estradiol ratio and SHBG were not associated with CVD events.

Conclusions: In community-dwelling elderly men, endogenous levels of testosterone, estradiol, and SHBG were not associated with increased risk of CHD, cerebrovascular, or PAD events. These results are limited by the small number of events and should be explored in future studies.
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http://dx.doi.org/10.1210/jendso/bvaa038DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173399PMC
May 2020

Genetic Burden Contributing to Extremely Low or High Bone Mineral Density in a Senior Male Population From the Osteoporotic Fractures in Men Study (MrOS).

JBMR Plus 2020 Mar 22;4(3):e10335. Epub 2020 Jan 22.

Department of Molecular and Human Genetics Baylor College of Medicine Houston TX USA.

Worldwide, one in five men aged over 50 years will experience osteoporosis or a clinical bone fracture, with a greater fracture-related mortality rate than women. However, the genetic etiology of osteoporosis in men is still poorly understood. We aimed to identify the genetic variants and candidate genes associated with extremely low or high BMD for a better understanding of the biology underlying low bone density that may point to potential therapeutic targets for increasing bone mass. Subjects from the Osteoporotic Fractures in Men Study (MrOS) cohort were evaluated by age and BMI-adjusted total hip BMD. Those with BMD values 3 SDs away from the mean were selected and the remaining individuals whose adjusted BMD ranked at the highest or lowest 100 were included. Men with the lowest adjusted BMD ( = 98) and highest adjusted BMD ( = 110) were chosen for exome sequencing. Controls ( = 82) were men of Northern and Western European descent from the US Utah population of the 1000 Genomes Project. Fisher's exact test was performed to compare low- or high-BMD subjects with controls for single-gene associations. Additionally, sets of candidate genes causative of heritable disorders of connective tissue, including osteogenesis imperfecta (OI) and Ehlers-Danlos syndrome (EDS), were grouped for multigene and mutation burden analyses. No single-gene associations with rare variants were found for either the low BMD group (33 genes) or high BMD group (18 genes). In the group of OI genes, we detected a significant threefold increased accumulation of rare variants in low-BMD subjects compared with controls ( = 0.009). Additionally, genes associated with EDS had a twofold increased frequency in low-BMD subjects compared with controls ( = 0.03). These findings reveal a rare variant burden in OI and EDS disease genes at low BMD, which suggests a potential gene-panel approach to screen for multivariant associations in larger cohorts. © 2019 The Authors. published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.
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http://dx.doi.org/10.1002/jbm4.10335DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7059823PMC
March 2020

Comparing Analytical Methods for the Gut Microbiome and Aging: Gut Microbial Communities and Body Weight in the Osteoporotic Fractures in Men (MrOS) Study.

J Gerontol A Biol Sci Med Sci 2020 06;75(7):1267-1275

Research Institute, California Pacific Medical Center, San Francisco.

Determining the role of gut microbial communities in aging-related phenotypes, including weight loss, is an emerging gerontology research priority. Gut microbiome datasets comprise relative abundances of microbial taxa that necessarily sum to 1; analysis ignoring this feature may produce misleading results. Using data from the Osteoporotic Fractures in Men (MrOS) study (n = 530; mean [SD] age = 84.3 [4.1] years), we assessed 163 genera from stool samples and body weight. We compared conventional analysis, which does not address the sum-to-1 constraint, to compositional analysis, which does. Specifically, we compared elastic net regression (for variable selection) and conventional Bayesian linear regression (BLR) and network analysis to compositional BLR and network analysis; adjusting for past weight, height, and other covariates. Conventional BLR identified Roseburia and Dialister (higher weight) and Coprococcus-1 (lower weight) after multiple comparisons adjustment (p < .0125); plus Sutterella and Ruminococcus-1 (p < .05). No conventional network module was associated with weight. Using compositional BLR, Coprococcus-2 and Acidaminococcus were most strongly associated with higher adjusted weight; Coprococcus-1 and Ruminococcus-1 were most strongly associated with lower adjusted weight (p < .05), but nonsignificant after multiple comparisons adjustment. Two compositional network modules with respective hub taxa Blautia and Faecalibacterium were associated with adjusted weight (p < .01). Findings depended on analytical workflow. Compositional analysis is advocated to appropriately handle the sum-to-1 constraint.
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http://dx.doi.org/10.1093/gerona/glaa034DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7447861PMC
June 2020

Red Cell Distribution Width Is a Risk Factor for Hip Fracture in Elderly Men Without Anemia.

J Bone Miner Res 2020 05 19;35(5):869-874. Epub 2020 Mar 19.

San Francisco Coordinating Center, California Pacific Medical Center Research Institute, San Francisco, CA, USA.

Red cell distribution width (RDW), routinely assessed as a component of a complete blood count (CBC), quantifies the variation in the size of red blood cells. It increases with age, and increased RDW predicts many aging-related diseases and mortality. However, whether it also predicts hip fracture is unknown. We prospectively evaluated the association between RDW and hip fracture using data from the Osteoporotic Fracture in Men (MrOS) study. RDW was measured in 3635 men (aged 71 to 99 years) along with bone mineral density (BMD) in MrOS. RDW ranged from 11.3% to 32.9% (median 14.0%; interquartile range 13.5% to 14.8%) and was categorized into four groups (≤13.0%, 13.1% to 14.0%, 14.1% to 15.0%, ≥15.1%). Study participants with a hemoglobin level <13.0 g/dL were classified as having anemia. During an average 8.1 years, 164 men suffered hip fractures. The risks of hip fractures increased with increase of RDW category. Furthermore, there was a significant interaction between anemia and RDW: An association between RDW and hip fractures was only observed in participants without anemia. In those without anemia, the relative hazard of hip fractures increased with increases in RDW category: Men in the highest RDW category had a 2.8 times higher risk of hip fractures than men in the lowest group (95% confidence interval 1.1 to 7.1). The risks of all-clinical fractures were also increased along with higher RDW values. Additionally, RDW was significantly associated with the risk of having a fall but not with femoral neck or total hip BMD. In conclusion, RDW and anemia defined by hemoglobin are widely available routine laboratory measurements that together could indicate increased risk of hip fracture, reflecting the neuromuscular effects of aging rather than lower hip BMD. © 2020 American Society for Bone and Mineral Research.
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http://dx.doi.org/10.1002/jbmr.3963DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7744556PMC
May 2020

Objective measures of moderate to vigorous physical activity are associated with higher distal limb bone strength among elderly men.

Bone 2020 03 20;132:115198. Epub 2019 Dec 20.

Division of Epidemiology & Community Health, University of Minnesota, Minneapolis, MN, United States of America; Department of Medicine, University of Minnesota, Minneapolis, MN, United States of America; Center for Care Delivery & Outcomes Research, VA Health Care System, Minneapolis, MN, United States of America.

Our aim was to determine the association between objectively measured physical activity (PA) and bone strength of the distal limbs among older men. We studied 994 men from the MrOS cohort study (mean age 83.9) who had repeat (Year 7 and 14) 5-day activity assessment with at least 90% wear time (SenseWearPro3 Armband) and Year 14 measures using high resolution peripheral quantitative tomography (HR-pQCT) (Scanco). Total energy expenditure (TEE), total steps per day, peak cadence (mean of top 30 steps/min over 24 h) and time spent in a given level of activity: sedentary (reference, <1.5 metabolic equivalents of task [METs]), light (1.5 to <3 METs), or moderate to vigorous physical activity(MVPA: ≥3 METs) were calculated as mean over the two time points. Estimated failure load was determined from HR-pQCT data using finite element analysis. We used standardized variables and adjusted for potential confounders using linear regression. The means ±SDs for daily activity were: 2338 ± 356 kcal/d [TEE]; 5739 ± 2696 steps/day [step count], 60 ± 20 cpm [peak cadence], 67 ± 28 min/d [light activity], and 85 ± 52 min/d [MVPA]. Higher TEE, step count, and peak cadence were each associated with higher failure load of the distal radius (effect sizes respectively: 0.13 [95% CI: 0.05, 0.20], 0.11 [95% CI: 0.04, 0.18], and 0.08 [95% CI: 0.01, 0.15]) and higher failure load of the distal tibia (effect sizes respectively 0.21 [95% CI: 0.13, 0.28], 0.19 [95% CI: 0.13, 0.26], 0.19 [95% CI, 0.13, 0.25]). Time spent in MVPA vs. time sedentary was related to bone strength at both sites after adjustment, whereas time spent in light activity vs. time sedentary was not. TEE was associated with compartmental area and BMD parameters at distal tibia, but only area parameters at the distal radius. In summary, MVPA over a 7-year period of time may have a modest association with bone strength and geometry among older men.
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http://dx.doi.org/10.1016/j.bone.2019.115198DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6993955PMC
March 2020

Association of change in muscle mass assessed by D -creatine dilution with changes in grip strength and walking speed.

J Cachexia Sarcopenia Muscle 2020 02 17;11(1):55-61. Epub 2019 Oct 17.

Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, CA, USA.

Background: Muscle mass declines with age. However, common assessments used to quantify muscle mass are indirect. The D -creatine (D Cr) dilution method is a direct assessment of muscle mass; however, longitudinal changes have not been examined in relation to changes in other measures of muscle mass, strength, and performance.

Methods: A convenience sample of 40 men from the Osteoporotic Fractures in Men Study (mean age = 83.3 years, standard deviation = 3.9) underwent repeat assessment of D Cr muscle mass, dual-energy X-ray absorptiometry (DXA) lean mass, grip strength, and walking speed at two time points approximately 1.6 years apart (2014-2016). One-sample t-tests and Pearson correlations were used to examine changes in DXA total body lean mass, DXA appendicular lean mass/height , DXA appendicular lean mass/weight, D Cr muscle mass, D Cr muscle mass/weight, grip strength, walking speed, and weight.

Results: D -creatine muscle mass, D Cr muscle mass/weight, grip strength, and walking speed all significantly declined (all P < 0.01). The change in DXA measures of lean mass was moderately correlated with changes in D Cr muscle mass. There was no significant correlation between the change in DXA measures of lean mass and change in walking speed (all P > 0.05). The change in D Cr muscle mass/weight was moderately correlated with change in walking speed (r = 0.33, P < .05). The change in grip strength was weakly correlated with the change in DXA measures of lean mass and D Cr muscle mass (r = 0.19-0.32).

Conclusions: The results of our study provide new insights regarding the decline in muscle strength and D Cr muscle mass. The D Cr method may be a feasible tool to measure declines in muscle mass over time.
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http://dx.doi.org/10.1002/jcsm.12494DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7015254PMC
February 2020

Association of dietary patterns with the gut microbiota in older, community-dwelling men.

Am J Clin Nutr 2019 10;110(4):1003-1014

Division of Epidemiology and Community Health, School of Public Health, University of Minnesota, Minneapolis, MN, USA.

Background: While the gut microbiota is relatively stable through adulthood, its composition is influenced by various host and environmental factors, including changes in health, gastrointestinal processes (e.g., transit time, gastric acidity), medication use, and diet. The association of habitual diet, in the form of a posteriori-derived dietary patterns, and microbiota composition has not been adequately studied, particularly in older men.

Objective: The objective was to investigate the association of dietary patterns with the composition and diversity of the gut bacterial microbiota in community-dwelling, older men.

Methods: This cross-sectional study included 517 men who were participants in the Osteoporotic Fractures in Men (MrOS) Study (≥65 y of age at baseline in 2000-2002) and who provided a stool sample and completed an FFQ at MrOS Visit 4 in 2014-2016. Dietary patterns were derived by factor analysis. 16S ribosomal RNA target gene sequencing was performed and taxonomy assignments were derived using the Greengenes database. Linear regression and permutational multivariate analysis of variance (PERMANOVA) considered variations in alpha and beta diversity by dietary pattern, and a model that implements a 0-inflated Gaussian distribution of mean group abundance for each taxa (metagenomeSeq) assessed taxonomic variations by dietary pattern.

Results: In multivariable-adjusted models, greater adherence to the Western pattern was positively associated with families Mogibacteriaceae and Veillonellaceae and genera Alistipes, Anaerotruncus, CC-115, Collinsella, Coprobacillus, Desulfovibrio, Dorea, Eubacterium, and Ruminococcus, while greater adherence to the prudent pattern was positively associated with order Streptophyta, family Victivallaceae, and genera Cetobacterium, Clostridium, Faecalibacterium, Lachnospira, Paraprevotella, and Veillonella. The relative abundance of the dominant gut bacterial phyla, Bacteroidetes and Firmicutes, did not differ between participants with greater adherence to the Western pattern, compared with those with greater adherence to the prudent pattern. Dietary patterns were not associated with measures of alpha diversity, but beta diversity measures were significantly associated with both Western and prudent patterns.

Conclusions: We observed significant associations between dietary patterns and measures of gut microbial composition in this sample of community-dwelling, older men.
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http://dx.doi.org/10.1093/ajcn/nqz174DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6766444PMC
October 2019
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