Low Lean Mass Predicts Incident Fractures Independently From FRAX: a Prospective Cohort Study of Recent Retirees

Defining sarcopenia in terms of skeletal health

Among several sarcopenic indices, height-adjusted appendicular lean mass (ALM) in men and BMI-adjusted ALM in women are associated with fragility fracture. Handgrip strength is the risk factor for fragility fracture.

PURPOSE

Various sarcopenia definitions and cutoff points result in mixed skeletal health results. Here, we aimed to determine a suitable definition and elucidate the cutoff values of sarcopenic indices for identifying fracture risk in a community-dwelling Korean cohort.

METHODS

In an Ansung cohort study (2009-2010), we included 1201 men aged > 50 years and 1627 postmenopausal women with a median age of 64 years. Body composition and bone mineral density were derived on dual-energy X-ray absorptiometry. Grip strength was measured using a hand dynamometer. Fragility fractures included the history of osteoporotic fractures using self-reported questionnaires.

RESULTS

Among appendicular lean mass (ALM)/body mass index (BMI), ALM/height², and ALM/weight, ALM/height² for men and ALM/BMI for women significantly predicted fragility fractures. On receiver operating characteristic curve analysis, the cutoff values of ALM/height² in men and ALM/BMI in women were 7.69 kg/m², and 0.57, respectively. The optimal grip strength values were 31 kg in men and 19 kg in women. The odds ratios of low ALM/height² (95% confidence interval) and weak grip strength for fragility fracture were 1.95 (1.03-3.68) and 2.05 (1.01-4.18), respectively, in men after covariate adjustment. The combination of low ALM/height² and weak grip strength increased fragility fractures 2.16-fold in men. Only the combination of low ALM/BMI and grip strength increased the fracture risk by 1.76-fold in women.

CONCLUSIONS

In men, low ALM/height² or grip strength played a role in fragility fractures. In women, only the combination of low ALM/BMI and grip strength had discriminatory power for fragility fractures.

Dysmobility Syndrome Independently Increases Fracture Risk in the Osteoporotic Fractures in Men (MrOS) Prospective Cohort Study

We proposed the term "dysmobility syndrome" (DS) to identify individuals with impaired musculoskeletal health, a risk factor for falls and fractures. Whether DS is associated with increased risk of incident fracture is unknown. The Osteoporotic Fractures in Men (MrOS) study enrolled 5994 men ages ≥65 years, between March 2000 and April 2002. We used baseline data to determine whether DS increased fracture risk, independent of the Fracture Risk Assessment Tool (FRAX). Men met DS criteria at baseline if they had three or more of the following: appendicular lean mass/height² <7.26 kg/m² , total body fat >30%, spine or hip T-score ≤ -2.5, grip strength <30 kg, gait speed <1.0 m/s, and one or more fall within 12 months. We examined whether baseline DS increased the risk of hip and major osteoporotic fractures (MOFs) over a median of 14 years (IQR, 9 to 15 years). Among 5834 men mean age 74 ± 6 years, 471 (8%) had DS and 635 (11%) experienced an MOF, including 274 (5%) hip fractures. Age (per SD increase) conferred an HR of 1.72 (95% CI, 1.59 to 1.86), DS conferred an HR of 3.45 (95% CI, 2.78 to 4.29) and FRAX calculated with BMD (per %) conferred an HR of 1.10 (95% CI, 1.08 to 1.11) for MOF. Prediction of MOF using the FRAX score provided a concordance value of 0.67 ± 0.012 (concordance values are mean ± SE). Concordance increased to 0.69 ± 0.012 by adding DS and to 0.70 ± 0.012 by adding DS and age to the multivariate model. Kaplan-Meier curves indicated that men with both DS and a FRAX risk above the National Osteoporosis Foundation (NOF) treatment thresholds had higher MOF (HR 6.23; 95% CI, 3.10 to 12.54) and hip (HR 7.73; 95% CI, 5.95 to 10.04) fracture risk than men with neither condition. We suggest further studies to determine the optimal criteria for DS, and to test DS as a predictor of falls and fractures, especially in women. © 2018 American Society for Bone and Mineral Research.

Sarcopenia as a predictor of hospitalization among older people: a systematic review and meta-analysis

Background

Previous cohort studies investigating the association between sarcopenia and the risk of hospitalization have been inconsistent. We performed a meta-analysis to determine if sarcopenia is a predictor of hospitalization.

Methods

Prospective cohort studies that evaluated the association between sarcopenia and hospitalization in older people were identified via a systematic search of four electronic databases (PubMed, EMBASE, Science Citation Index, and the Cochrane Library). A random-effect model was applied to combine the results according to the heterogeneity of the included studies.

Results

Five studies (2832 participants) were included in this meta-analysis. Pooled results demonstrated that older people with sarcopenia were at an increased risk of hospitalization (pooled hazards ratio [HR] = 1.57, 95% confidence interval [CI] = 1.26, 1.94, I² = 4.5%, P = 0.000) compared to those without sarcopenia. Results of subgroup analyses showed that hospitalized patients with sarcopenia had a higher rate of hospitalization (HR = 2.01, 95% CI = 1.41, 2.88, p = 0.000) versus patients without sarcopenia. A similar result was also found in community-dwelling older people with sarcopenia versus those without sarcopenia (HR = 1.40, 95% CI = 1.05, 1.88, p = 0.023). In addition, the subgroup analysis for length of follow-up showed that studies with a follow-up period of 3 years or more (pooled HR = 1.52, 95% CI = 1.19, 1.94, P = 0.001) reported a significantly higher rate of hospitalization among individuals with sarcopenia compared to those without sarcopenia. However, this association was not found in the studies with a follow-up period of less than 3 years (pooled HR = 1.76, 95% CI = 0.90, 3.44, P = 0.099).

Conclusions

Sarcopenia is a significant predictor of hospitalization among older individuals, and the association may not be significantly affected by the characteristics of the population or the definition of sarcopenia.

Electronic supplementary material

The online version of this article (10.1186/s12877-018-0878-0) contains supplementary material, which is available to authorized users.

Sarcopenia

Sarcopenia is defined as a combination of low muscle mass with low muscle function. The term was first used to designate the loss of muscle mass and performance associated with aging. Now, recognized causes of sarcopenia also include chronic disease, a physically inactive lifestyle, loss of mobility, and malnutrition. Sarcopenia should be differentiated from cachexia, which is characterized not only by low muscle mass but also by weight loss and anorexia. Sarcopenia results from complex and interdependent pathophysiological mechanisms that include aging, physical inactivity, neuromuscular compromise, resistance to postprandial anabolism, insulin resistance, lipotoxicity, endocrine factors, oxidative stress, mitochondrial dysfunction, and inflammation. The prevalence of sarcopenia ranges from 3% to 24% depending on the diagnostic criteria used and increases with age. Among patients with rheumatoid arthritis 20% to 30% have sarcopenia, which correlates with disease severity. Sarcopenia exacts a heavy toll of functional impairment, metabolic disorders, morbidity, mortality, and healthcare costs. Thus, the consequences of sarcopenia include disability, quality of life impairments, falls, osteoporosis, dyslipidemia, an increased cardiovascular risk, metabolic syndrome, and immunosuppression. The adverse effects of sarcopenia are particularly great in patients with a high fat mass, a condition known as sarcopenic obesity. The diagnosis of sarcopenia rests on muscle mass measurements and on functional tests that evaluate either muscle strength or physical performance (walking, balance). No specific biomarkers have been identified to date. The management of sarcopenia requires a multimodal approach combining a sufficient intake of high-quality protein and fatty acids, physical exercise, and antiinflammatory medications. Selective androgen receptor modulators and anti-myostatin antibodies are being evaluated as potential stimulators of muscle anabolism.

Association of Decreased Handgrip Strength with Reduced Cortical Thickness in Japanese Female Patients with Type 2 Diabetes Mellitus

LD-100, a quantitative ultrasonic device, allows us to measure cortical thickness (CoTh). Patients with type 2 diabetes mellitus (T2DM) show high prevalence of sarcopenia. This study aimed to clarify the association of handgrip strength (HGS) with cortical porosis, a major risk for fracture of DM. CoTh and trabecular bone mineral density (TrBMD) at the 5.5% distal radius were assessed in T2DM female patients (n = 122) and non-DM female controls (n = 704) by LD-100. T2DM patients aged older 40 years showed significantly lower HGS and CoTh, but not TrBMD, than non-DM counterparts. Although HGS was significantly and positively correlated with CoTh and TrBMD in T2DM patients, multivariate analysis revealed HGS as an independent factor positively associated with CoTh, but not TrBMD, in T2DM patients, suggesting the preferential association of HGS with cortical, but not trabecular, bone component in T2DM female patients. In conclusion, the present study demonstrated an early decline of HGS in T2DM female patients as compared with non-DM healthy controls after the age of 40 years, which is independently associated with thinner CoTh, but not TrBMD in T2DM patients, and thus suggested that reduced muscle strength associated with DM might be a major factor for cortical porosis development in DM patients.

Association of sarcopenia and fractures in community-dwelling older adults: a systematic review and meta-analysis of cohort studies

To our knowledge, no comprehensive meta-analysis has examined the association between sarcopenia and the risk of fractures. This systematic review and meta-analysis of prospective cohort studies aims to summarize whether sarcopenia is a risk factor for fractures among community-dwelling older adults. We searched four electronic literature databases (Ovid MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, PubMed) for relevant publications from inception to December 2017, using relevant keywords. We conducted a pooled analysis of the association between sarcopenia and the risk of fractures by employing a random-effects model. Subgroup analyses were conducted based on definitions of sarcopenia and gender. In total, nine studies were included in our systematic review and meta-analysis. The prevalence of sarcopenia ranged from 4.3 to 33.1%. The pooled RR of fractures for the sarcopenic versus the nonsarcopenic was 1.34 (95% CI = 1.13-1.58, P = 0.001, I² = 5.5%, P-heterogeneity = 0.391). Subgroup analyses showed that associations between sarcopenia and fractures were significant when using the AWGS definition (combined effect size = 1.78, 95% CI = 1.25-2.54, P = 0.001), and studies in males (combined effect size = 1.39, 95% CI = 1.13-1.71, P = 0.002). In conclusion, we found that compared to nonsarcopenic, the association between sarcopenia and fractures among community-dwelling older people was significant when using the AWGS definition, and only for males. Future studies are needed to establish a possible association between sarcopenia definitions and risk of fractures of different sites.

Association between site-specific bone mineral density and glucose homeostasis and anthropometric traits in healthy men and women

OBJECTIVE

Patients with type 2 diabetes mellitus have an increased risk of fracture despite normal or increased bone mineral density (BMD). Studies on the relationship of glucose homeostasis with BMD phenotypes have been inconclusive because distinguishing the roles of insulin resistance and hyperglycaemia in bone remodelling is challenging. In this study, we sought to define the relationship of site-specific BMD with glucose homeostasis traits and anthropometric traits.

DESIGN/PATIENTS/MEASUREMENTS

In a cross-sectional study, we examined 787 subjects from the Mexican-American Coronary Artery Disease (MACAD) cohort who had undergone euglycaemic-hyperinsulinaemic clamps, oral glucose tolerance testing and dual X-ray absorptiometry. Glucose homeostasis traits included insulinogenic index (IGI30), insulin sensitivity (M value), insulin clearance (MCRI), fasting insulin, fasting glucose and 2-hour glucose. Univariate and multivariate analyses were performed to assess the association of glucose homeostasis and anthropometric traits with site-specific BMD.

RESULTS

Two-hour glucose was negatively associated with arm BMD in women, which remained significant in multivariate analysis (β = -.15, P = .0015). Positive correlations between fasting insulin and BMD at weight-bearing sites, including pelvis (β = .22, P < .0001) and legs (β = .17, P = .001) in women and pelvis (β = .33, P < .0001) in men, lost significance after multivariate adjustment. Lean mass exhibited strong independent positive associations with BMD at multiple sites in both sexes.

CONCLUSION

Our findings suggest that (i) anabolic effects of insulin might work via mechanical loading from lean mass; (ii) a direct negative effect of increasing glucose might be more prominent at cortical-bone-rich sites in women; and (iii) lean mass is a strong positive predictor of bone mass.

Impact of cross-sex hormone therapy on bone mineral density and body composition in transwomen

OBJECTIVE

Cross-sex hormone therapy (CSHT) has been associated with changes in bone and lean/fat mass. This study assessed bone mineral density (BMD), appendicular lean mass (ALM), and total fat mass in transwomen undergoing CSHT.

PATIENTS AND DESIGN

We evaluated 142 transwomen (mean age: 33.7 ± 10.3 years; BMI: 25.4 ± 4.6; 86.6% with previous CSHT) during the first 3 months of regular oestrogen treatment (with or without anti-androgens). A reference group including 22 men and 17 cis women was also studied.

MEASUREMENTS

Clinical and hormonal evaluation and dual-energy X-ray absorptiometry (DXA).

RESULTS

Bone mineral density was similar in trans and reference women, and lower at all sites in transwomen vs men. Low bone mass for age was observed in 18% of transwomen at baseline vs none of the reference women or men. Appendicular lean mass and total fat mass were positively correlated with L1-L4 BMD, explaining 14.9% of the observed variation in lumbar spine BMD and 20.6% of the variation in total femur BMD. Appendicular lean mass was similar in trans and reference women, and lower in transwomen vs men. Total fat mass was lower in trans vs reference women. Densitometry was repeated after a mean of 31.3 ± 6.5 months in 46 transwomen. There was a significant increase in total fat mass and a significant decrease in ALM. Bone mineral density remained stable over time.

CONCLUSIONS

The fairly high prevalence of low bone mass in this sample of transwomen from southern Brazil seems to be related to lower ALM. Non-pharmacological lifestyle-related strategies for preventing bone loss could be beneficial for transgender women receiving long-term CSHT.

Association of High Anti-Cyclic Citrullinated Peptide Seropositivity and Lean Mass Index With Low Bone Mineral Density in Rheumatoid Arthritis

OBJECTIVE

Osteoporotic fractures are associated with high morbidity and mortality. Persons with rheumatoid arthritis (RA) have twice the risk of osteoporosis-related fracture than age-matched controls, the causes for which remain unknown. We investigated contributions of RA characteristics, medication use, and body composition to low bone mineral density (BMD) in patients with RA.

METHODS

Data were from the Arthritis, Body Composition, and Disability Study (n = 138; 82 women, 56 men). Demographic, clinical, laboratory, and functional variables were collected at study visits. Body composition (fat, lean muscle, and BMD) was measured by dual x-ray absorptiometry. Linear regression analyses evaluated the association between predictors and femoral neck BMD.

RESULTS

Average disease duration was 19 years, 70% of patients were rheumatoid factor positive, and 55% were high-positive anti-cyclic citrullinated peptide (anti-CCP). Age and high anti-CCP positivity were negatively associated with BMD after controlling for other variables (β = -0.003 and -0.055, respectively, P < 0.05). Appendicular lean mass index (ALMI) was positively associated with BMD (β = 0.053, P < 0.0001). In high anti-CCP positivity participants, increasing anti-CCP levels were associated with a negative linear trend in BMD (β = -0.011, P = 0.026).

CONCLUSION

High anti-CCP positivity and ALMI were strongly associated with BMD in patients with RA. The linear relationship of anti-CCP levels with lower BMD supports the hypothesis that processes specific to RA negatively impact BMD. In contrast, ALMI was positively associated with BMD, emphasizing the importance of this potentially modifiable risk factor. Our findings highlight the complicated interplay of RA disease-specific and functional factors and their impact on bone mass.

Bone health assessment in older people with or without muscle health impairment

This study investigated the relationship between muscle and bone status in elderly individuals. Our results suggested links between sarcopenia and osteoporosis; impairment in muscle status (i.e., muscle mass, muscle strength, and physical performance) is associated with deterioration in bone mass and texture subsequently leading to an increased risk of fracture.

INTRODUCTION

Accumulating evidence has shown associations between sarcopenia and osteoporosis, but existing studies face inconsistencies in the clinical definition of both conditions. Thus, we sought to investigate bone health among older individuals with or without muscle health impairment.

METHODS

We conducted an analysis of cross-sectional data available from the Sarcopenia and Physical Impairment with Advancing Age (SarcoPhAge) study. Sarcopenia was diagnosed according to the European Working Group on Sarcopenia in Older People (EWGSOP) (i.e., a low muscle mass plus either low muscle strength or low physical performance). Muscle mass and areal bone mineral density (aBMD) were determined using dual-energy X-ray absorptiometry (DEXA). Muscle strength was assessed using a hand dynamometer, and physical performance was assessed with the Short Physical Performance Battery test. Using the cutoff limits proposed by the EWGSOP, we have classified women in the "low SMI group" when its value was < 5.50 kg/m², in the "low muscle strength group" when strength was < 20 kg, and in the "low physical performance group" when SPPB < 8 points. The thresholds of < 7.26 kg/m² (for SMI), < 30 kg (for muscle strength), and SPPB < 8 points were used for men. The 10-year fracture risk was obtained using the FRAX® tool. Moreover, bone texture was determined using the trabecular bone score (TBS) method.

RESULTS

The study sample consisted of 288 older subjects aged 74.7 ± 5.7 years, and 59.0% of the subjects were women. Sarcopenia was diagnosed in 43 individuals (14.9%), and osteoporosis was diagnosed in 36 subjects (12.5%). Moreover, aBMD values were, most of the time, lower in older men and women with muscle impairment (i.e., low muscle mass, low muscle strength, and low physical performance). For these subjects, we also noted a higher probability of fracture. When comparing bone quality, there were no significant differences in the TBS values between sarcopenic and non-sarcopenic older men and women or between those with low and high muscle mass. However, when controlling for confounders (i.e., age, BMI, number of co-morbidities, smoking status, and nutritional status), TBS values were lower in older women with low muscle strength (p = 0.04) and in older men with low physical performance (p = 0.01).

CONCLUSIONS

Our study showed interrelationships between components of sarcopenia and osteoporosis, with older subjects with muscle impairment having poorer bone health.

Quality of life assessment in musculo-skeletal health

Musculoskeletal disorders affect morbidity, quality of life and mortality, and represent an increasing economic and societal burden in the context of population aging and increased life expectancy. Improvement of quality of life should be one of the priorities of any interventions to prevent and treat musculoskeletal disorders in the ageing population. Two main approaches, namely generic and disease-specific instruments, can be applied to measure health-related quality of life. Among the generic tools available in scientific literature, the short form 36 questionnaire (SF-36) and the Euroqol five item questionnaire (EQ-5D) are two of the most popular questionnaires used to quantify the health related quality of life in people with musculoskeletal disorders. However, because generic tools may not always be able to detect subtle effects of a specific condition on quality of life, a specific tool is highly valuable. Specific tools improve the ability to clinically characterize quality of life in subjects with a specific musculoskeletal disorder, as well as the capacity to assess changes over time in the QoL of these subjects. The recent development of specific tools should help to validate preventive and therapeutic interventions in this field.

Evaluation of Radius Microstructure and Areal Bone Mineral Density Improves Fracture Prediction in Postmenopausal Women

A majority of low-trauma fractures occur in subjects with only moderate decrease of areal bone mineral density (aBMD), ie, osteopenia, assessed by dual-energy X-ray absorptiometry (DXA) or low fracture probability assessed by FRAX. We investigated whether peripheral bone microstructure and estimated strength improve the prediction of incident fractures beyond central DXA and FRAX. In this population-based study of 740 postmenopausal women (aged 65.0 ± 1.4 years) from the Geneva Retirees Cohort (ISRCTN registry 11865958), we assessed at baseline cortical (Ct) and trabecular (Tb) volumetric bone mineral density (vBMD) and microstructure by peripheral quantitative computed tomography (HR-pQCT); bone strength by micro-finite element analysis; aBMD and trabecular bone score (TBS) by DXA; and FRAX fracture probability. Eighty-five low-trauma fractures occurred in 68 women over a follow-up of 5.0 ± 1.8 years. Tb and Ct vBMD and microstructure predicted incident fractures, independently of each other and of femoral neck (FN) aBMD and FRAX (with BMD ± TBS). However, the associations were markedly attenuated after adjustment for ultra-distal radius aBMD (same bone site). The best discrimination between women with and without fracture was obtained at the radius with total vBMD, the combination of a Tb with a Ct parameter, or with failure load, which improved the area under the curve (AUC) for major osteoporotic fracture when added to FN aBMD (0.760 versus 0.695, p = 0.022) or to FRAX-BMD (0.759 versus 0.714, p = 0.015). The replacement of failure load by ultra-distal aBMD did not significantly decrease the AUC (0.753, p = 0.747 and 0.750, p = 0.509, respectively). In conclusion, peripheral bone microstructure and strength improve the prediction of fractures beyond central DXA and FRAX but are partially captured in aBMD measured by DXA at the radius. Because HR-pQCT is not widely available for clinical purposes, assessment of ultra-distal radius aBMD by DXA may meanwhile improve fracture risk estimation. © 2017 American Society for Bone and Mineral Research.

Low Skeletal Muscle Mass is Associated with the Risk of Low Bone Mineral Density in Urban Dwelling Premenopausal Women

To evaluate the relationship between skeletal muscle mass and bone mineral density (BMD) and to determine the association between low skeletal muscle mass and low BMD in urban dwelling young adults. This study was based on data from the 2008-2011 Korea National Health and Nutrition Examination Surveys. The subjects were 1702 20-49-year-old men and 2192 premenopausal women (age 20-55 years). BMD at the lumbar spine, femoral neck, and total hip and the appendicular skeletal muscle mass (ASM) were measured by dual-energy X-ray absorptiometry. Skeletal muscle mass index (SMI) was defined as weight-adjusted ASM. Mildly and severely low muscle skeletal mass were defined as SMI that was 1-2 and >2 standard deviations below the sex-specific mean ASM of young adults, respectively. Low BMD was defined as T score of less than -1.0 at the lumbar spine, femoral neck, and/or total hip. After adjusting for confounders, skeletal muscle mass was positively associated with BMD at the lumbar spine, femoral neck, and total hip in both men and women. Mildly and severely low skeletal muscle mass increased the risk of low BMD in premenopausal women [OR (95% CI) = 1.4 (1.1-1.9) and 2.4 (1.2-4.6), respectively] but not men. In women, low skeletal muscle mass independently was associated with the risk of low BMD at the femoral neck and total hip but not the lumbar spine. Skeletal muscle mass was independently associated with BMD in urban dwelling young men and women, but low skeletal muscle mass was associated with the risk of low BMD in premenopausal women only.

Development of a New Immunoassay for Human Cathepsin K-Generated Periostin Fragments as a Serum Biomarker for Cortical Bone

Periostin is a matricellular protein mainly expressed by periosteal cells and osteocytes in bone, but is also present in several other tissues. Available immunoassays use antibodies of unclear specificity. The aim of the study was to develop a bone-specific periostin ELISA based on the detection of fragments generated by the osteoclastic and osteocytic protease cathepsin K. In vitro digestion of human recombinant intact periostin by cathepsin K leads to the generation of multiple fragments. Using LS-MS/MS, it was found that the GSLQPIIK peptide was the most efficiently and abundantly generated periostin fragment. A rabbit polyclonal antibody directed against the synthetic GSLQPIIK sequence was produced. Immunohistochemistry experiments of the tibia showed that the GSLQPIIK fragments localized at the periosteal surface and within the osteocytes. Using the same antibody, we developed an ELISA for the measurement of GSLQPIIK in the serum. This ELISA demonstrated intra- and interassay variability below 14% with a sensitivity allowing accurate determinations in the serum of healthy individuals. Serum GSLQPIIK was measured in 160 healthy postmenopausal women (mean age 65 year) participating in the Geneva Retiree Cohort. Serum GSLQPIIK levels did not correlate with total periostin, hip BMD, and the bone markers PINP and CTX. However, GSLQPIIK was negatively correlated (p values ranging from 0.007 to 0.03) with Hr-pQCT measures of tibia and radius cortical bone, but not with trabecular parameters. We have developed the first assay for the detection of periostin fragments generated by cathepsin K. Because serum levels of this new marker significantly correlated with cortical bone measurements in postmenopausal women, it may prove to be useful for the clinical investigation of patients with osteoporosis.

Factors Associated with Decreased Lean Tissue Index in Patients with Chronic Kidney Disease

Muscle wasting is common and is associated with increased morbidity and mortality in patients with chronic kidney disease (CKD). However, factors associated with decreased muscle mass in CKD patients are seldom reported. We performed a cross-sectional study of 326 patients (age 65.8 ± 13.3 years) with stage 3–5 CKD who were not yet on dialysis. Muscle mass was determined using the Body Composition Monitor (BCM), a multifrequency bioimpedance spectroscopy device, and was expressed as the lean tissue index (LTI, lean tissue mass/height²). An LTI of less than 10% of the normal value (low LTI) indicates muscle wasting. Patients with low LTI (n = 40) tended to be diabetic, had significantly higher fat tissue index, urine protein creatinine ratio, and interleukin-6 and tumor necrosis factor-α levels, but had significantly lower serum albumin and hemoglobin levels compared with those with normal LTI. In multivariate linear regression analysis, age, sex, cardiovascular disease, and interleukin-6 were independently associated with LTI. Additionally, diabetes mellitus remained an independent predictor of muscle wasting according to low LTI by multivariate logistic regression analysis. We conclude that LTI has important clinical correlations. Determination of LTI may aid in clinical assessment by helping to identify muscle wasting among patients with stage 3–5 CKD.

Modified Creatinine Index and the Risk of Bone Fracture in Patients Undergoing Hemodialysis: The Q-Cohort Study

BACKGROUND

Hemodialysis patients are at increased risk for bone fracture and sarcopenia. There is close interplay between skeletal muscle and bone. However, it is still unclear whether lower skeletal muscle mass increases the risk for bone fracture.

STUDY DESIGN

Cross-sectional study and prospective longitudinal cohort study.

SETTING & PARTICIPANTS

An independent cohort of 78 hemodialysis patients in the cross-sectional study and 3,030 prevalent patients undergoing maintenance hemodialysis prospectively followed up for 4 years.

PREDICTOR

Skeletal muscle mass measured by bioelectrical impedance analysis (BIA) and modified creatinine index, an estimate of skeletal muscle mass based on age, sex, Kt/V for urea, and serum creatinine level.

OUTCOMES

Bone fracture at any site.

RESULTS

In the cross-sectional study, modified creatinine index was significantly correlated with skeletal muscle mass measured by BIA. During a median follow-up of 3.9 years, 140 patients had bone fracture. When patients were divided into sex-specific quartiles based on modified creatinine index, risk for bone fracture estimated by a Fine-Gray proportional subdistribution hazards model with all-cause death as a competing risk was significantly higher in the lower modified creatinine index quartiles (Q1 and Q2) compared to the highest modified creatinine index quartile (Q4) as the reference value in both sexes (multivariable-adjusted HRs for men were 7.81 [95% CI, 2.63-23.26], 5.48 [95% CI, 2.08-14.40], 2.24 [95% CI, 0.72-7.00], and 1.00 [P for trend < 0.001], and for women were 4.44 [95% CI, 1.50-13.11], 2.33 [95% CI, 0.86-6.31], 1.96 [95% CI, 0.82-4.65], and 1.00 [P for trend = 0.007] for Q1, Q2, Q3, and Q4, respectively).

LIMITATIONS

One-time assessment of modified creatinine index; no data for residual kidney function and fracture sites and causes.

CONCLUSIONS

Modified creatinine index was correlated with skeletal muscle mass measured by BIA. Lower modified creatinine index was associated with increased risk for bone fracture in male and female hemodialysis patients.

Low serum concentrations of Irisin are associated with increased risk of hip fracture in Chinese older women

OBJECTIVE

Irisin derived from muscle in response to exercise may be the molecular entity responsible for muscle wasting-osteoporosis connectivity in the elderly. The objective of the study was to determine whether serum Irisin (sIrisin) provides information on hip fracture prediction which were independent of bone mineral density (BMD) and the fracture risk assessment tool (FRAX) algorithm.

METHODS

This study enrolled 160 older women (ages, 70-90y) with minimal trauma hip fractures (MTHFs) and 160 age-matched women without fracture serving as controls. Clinical features, BMD and bone turnover markers including sIrisin levels were measured after fracture within 2 days as baseline.

RESULTS

sIrisin levels were significantly lower (361.5±140.0ng/mL vs 478.5±159.6ng/mL, P<0.001) in cases than controls. After multivariate analysis, sIrisin remained as an independent variable of BMD, which explained 17.8% of femoral neck BMD and 22.5% of lumbar spine BMD, respectively. The odds ratio (OR) of MTHFs comparing the lowest (<320.1ng/mL) to highest (>524.5ng/mL) quartiles was 1.95 (95% CI 1.23-3.79, P<0.05) for sIrisin. Adjustment for age, body mass index, time since menopause and exercise ≥30min/day yielded similar results, and BMD of femoral neck also did not change these associations. Taking FRAX score into account attenuated the association somewhat: OR of hip fracture was 1.81 (95% CI 1.26-3.49, P<0.05) in first versus fourth quartile of sIrisin. There was a negative gradient of risk by decreasing quartile in sIrisin.

CONCLUSIONS

Low concentrations of sIrisin in older women were independently associated with increased risk of hip fractures when adjusted for BMD or FRAX score.

Sarcopenic Obesity and Its Temporal Associations With Changes in Bone Mineral Density, Incident Falls, and Fractures in Older Men: The Concord Health and Ageing in Men Project

Body composition and muscle function have important implications for falls and fractures in older adults. We aimed to investigate longitudinal associations between sarcopenic obesity and its components with bone mineral density (BMD) and incident falls and fractures in Australian community-dwelling older men. A total of 1486 men aged ≥70 years from the Concord Health and Ageing in Men Project (CHAMP) study were assessed at baseline (2005-2007), 2-year follow-up (2007-2009; n = 1238), and 5-year follow-up (2010-2013; n = 861). At all three time points, measurements included appendicular lean mass (ALM), body fat percentage and total hip BMD, hand-grip strength, and gait speed. Participants were contacted every 4 months for 6.1 ± 2.1 years to ascertain incident falls and fractures, the latter being confirmed by radiographic reports. Sarcopenic obesity was defined using sarcopenia algorithms of the European Working Group on Sarcopenia (EWGSOP) and the Foundation for the National Institutes of Health (FNIH) and total body fat ≥30% of total mass. Sarcopenic obese men did not have significantly different total hip BMD over 5 years compared with non-sarcopenic non-obese men (p > 0.05). EWGSOP-defined sarcopenic obesity at baseline was associated with significantly higher 2-year fall rates (incidence rate ratio [IRR] 1.66; 95% confidence interval [CI] 1.16-2.37), as were non-sarcopenic obesity (1.30; 1.04-1.62) and sarcopenic non-obesity (1.58; 1.14-2.17), compared with non-sarcopenic non-obese. No association with falls was found for sarcopenic obesity using the FNIH definition (1.01; 0.63-1.60), but after multivariable adjustment, the FNIH-defined non-sarcopenic obese group had a reduced hazard for any 6-year fracture compared with sarcopenic obese men (hazard ratio 0.44; 95% CI 0.23-0.86). In older men, EWGSOP-defined sarcopenic obesity is associated with increased fall rates over 2 years, and FNIH-defined sarcopenic obese men have increased fracture risk over 6 years compared with non-sarcopenic obese men. © 2016 American Society for Bone and Mineral Research.