Background/Aims: Growth differentiation factor-15 (GDF-15) expression has been reported to increase in response to tissue damage and has recently emerged as a useful biomarker for various diseases. ...Although emerging evidence supports the clinicopathological value of GDF-15 in renal impairment, few studies have analyzed it in the elderly. Thus, we conducted a cross-sectional study to investigate the association of plasma GDF-15 with renal function and the presence of chronic kidney disease (CKD) in community-dwelling elderly. Materials: The present study was based on the baseline data of the Korean Frailty and Aging Cohort Study (KFACS), a nationwide cohort study that began in 2016. Of the 1,559 participants assessed in the first year, 443 with available plasma GDF-15 data were enrolled in this study. We investigated the association of plasma GDF-15 levels with clinical and biochemical parameters. The study population was divided into two groups according to renal function (CKD and non-CKD groups) to investigate whether GDF-15 can determine the presence of renal dysfunction in the elderly. Plasma GDF-15 was measured by enzyme-linked immunosorbent assay (ELISA) kit. Results: In a simple regression analysis, the levels of plasma GDF-15 were negatively correlated with estimated glomerular filtration rate (eGFR; r = –0.383, p < 0.001). In multiple linear regression analysis, GDF-15 levels were still significantly correlated with eGFR, even after adjusting for other parameters (r = –0.259, p < 0.001). Plasma GDF-15 levels were significantly higher in the elderly with CKD than in those without CKD (2,364.025 ± 1,052.23 ng/L and 1,451.23 ± 835.79 ng/L, respectively; p < 0.001). The optimal cut-off value of plasma GDF-15 for detecting the presence of CKD was 1,699.4 ng/L (76.5% sensitivity and 76.0% specificity), as determined by the receiver operating characteristic curve. The area under the curve was 0.793 ± 0.033 (95% CI 0.729–0.857, p < 0.001). Conclusion: Plasma GDF-15 levels were negatively associated with eGFR and were significantly increased in the elderly with CKD. Our results suggested that plasma GDF-15 might be a useful marker for discriminating renal impairment in the elderly. Further large and prospective outcome studies of extended duration are needed.
•The manual timer systematically underestimated usual gait speed in community settings.•The static start protocol showed a higher prevalence of slowness than the dynamic start protocol.•The automatic ...timer may be useful for measuring gait speed in healthy older adults.
This study aimed to compare 4-m usual gait speed obtained with different protocols and to determine the prevalence of slowness using different diagnostic criteria in a large cohort of community-dwelling older adults.
A total of 1177 non-disabled community-dwelling older adults aged 70–84 years were assessed for 4-m usual gait speed using four different testing protocols: (1) automatic timer (ultrasonic sensor), dynamic start; (2) manual timer (stopwatch), dynamic start; (3) automatic timer, static start; and (4) manual timer, static start. To assess agreement between usual gait speed and the testing protocols, linear regression and Bland-Altman analyses were performed.
There was systematic bias (i.e., difference between automatic timer and manual timer methods), with underestimation of usual gait speed (bias 0.0695 m/s for dynamic start; bias 0.0702 m/s for static start) by the manual timer. There was systematic bias in start conditions, with underestimation of usual gait speed with a static start using both timer methods, compared with that in dynamic start assessment (P < 0.001). The prevalence of slowness ranged from 2.3 to 4.7% in men and 5.9–11.1% in women for <0.80 m/s, and from 17.1 to 30.5% in men and 26.3–45.9% in women for <1.00 m/s.
The findings of this study indicated that 4-m usual gait speed measured under different testing protocols was able to determine different prevalence rates of slowness among non-disabled community-dwelling older adults. An automatic timer may be useful for measuring gait speed changes in individuals likely to have faster gait speed in community-based research settings.
The aging population contributes to increasing economic and social burden worldwide. Sarcopenia, an age-related degenerative disease and progressive disorder, is characterized by a reduction in ...skeletal muscle mass and function. This study aims to assess the association between dietary factors and sarcopenia in the Korean elderly using nationwide data. A total of 801 subjects aged 70-84 years were included in this analysis. Subjects were divided into two groups: sarcopenic and nonsarcopenic groups according to the sarcopenia criteria established by the Asian Working Group for Sarcopenia. Nutrient and food intakes were assessed using a 24-h recall method. Logistic regression analysis was used to assess the association between sarcopenia and food group and nutrient intakes. In the multivariable models, the meat/fish/egg/legume food group, vegetable group, and total food intake were inversely associated with the prevalence of sarcopenia. The high intakes of energy, carbohydrate, protein, fiber, zinc, carotene, and vitamin B
were associated with the lower prevalence of sarcopenia. Therefore, consuming sufficient nutrients through various protein source foods and vegetables will help prevent sarcopenia in the Korean elderly.
Electromagnetic interference (EMI) shielding for visual observation applications, such as windows utilized in military or aerospace, is important but difficult to realize due to conventional ...materials having difficulty in achieving sufficient transparency and EMI shielding simultaneously. In this paper, we present multilayered structures based on salt water for simultaneous highly optical transparency (OT) and EM shielding effectiveness (SE) performance. In the proposed structures, planar acrylic and glass were used as two types of clear substrates to hold salt water. The measured OT of both acrylic/salt water/acrylic and glass/salt water/glass structures was higher than 90% with a nearly uniform light transmission, which introduced a negligible impact on optical observation. Furthermore, both simulations and experimental results demonstrated that the SE of the multilayer structure was higher than 20 dB in the X-band from 7.5 to 8.5 GHz. Moreover, the SE was significantly enhanced by increasing the thickness of the salt water layer. Especially, both OT and SE of the multilayered structures were improved simultaneously by increasing the salinity of the salt water. These proposed structures demonstrate great potential in EMI shielding observation applications.
Background
Sarcopenia is commonly observed in patients with cardiovascular diseases. However, studies on the association between sarcopenia and atrial fibrillation and their causal relationships are ...limited. We performed cross‐sectional and longitudinal analyses to investigate the association between sarcopenia and atrial fibrillation among community‐dwelling older adults.
Methods
A total of 2225 participants from the Korean Frailty and Aging Cohort Study (KFACS) from 2016 to 2017 were included in this cross‐sectional analysis. Sarcopenia was defined according to the Asian Working Group for Sarcopenia 2019 consensus. Atrial fibrillation was diagnosed on the basis of electrocardiographic findings. We investigated whether atrial fibrillation increased the risk of incident sarcopenia 2 years later and whether sarcopenia, in turn, increased the 2‐year risk of developing atrial fibrillation using KFACS data from 2018 to 2019.
Results
Of the 2225 participants (54.2% women; mean age 76.0 ± 3.9 years), 509 (22.9%) had sarcopenia at baseline. In the cross‐sectional analysis, sarcopenia was associated with atrial fibrillation after multivariate adjustment odd ratio (OR), 2.127; 95% confidence interval (CI), 1.240–3.648; P = 0.006. Among the sarcopenia components, low physical performance was associated with atrial fibrillation (OR, 1.872; 95% CI, 1.123–3.120; P = 0.016). During the 2‐year follow‐up period, atrial fibrillation was not associated with new‐onset of sarcopenia (OR, 1.483; 95% CI, 0.597–3.685; P = 0.396), and sarcopenia also did not significantly increase the risk of incident atrial fibrillation (OR, 1.120; 95% CI, 0.384–3.264; P = 0.836).
Conclusions
Although we found a significant association between sarcopenia and atrial fibrillation in a cross‐sectional analysis, we could not establish a causal relationship between the two based on 2 years of follow‐up. Further research with long‐term follow‐up is required to identify causal relationship between atrial fibrillation and sarcopenia.
PurposeThe purpose of the Korean Frailty and Aging Cohort Study (KFACS) is to initiate a nationwide, population-based prospective cohort study of older adults living in the community to assess their ...frailty status and explore transitions between frailty states over time in Korea.ParticipantsThe KFACS is a multicentre longitudinal study with the baseline survey conducted from May 2016 to November 2017. Each centre recruited participants using quota sampling stratified by age and sex. The number of participants recruited through 2 years of baseline study from 10 centres was 3014, with each site accounting for approximately 300 participants. The inclusion criteria were: having an age of 70–84 years, currently living in the community, having no plans to move out in the next 2 years, having no problems with communication and no prior dementia diagnosis.Findings to dateTo define physical frailty, the KFACS used a modified version of the Fried Frailty Phenotype (FFP) consisting of five components of frailty: unintended weight loss, weakness, self-reported exhaustion, slowness and low physical activity. In the baseline study of 2016–2017, 2907 of 3014 individuals fulfilled all five components of FFP. The results indicated that 7.8% of the participants (n=228) were frail, 47.0% (n=1366) were prefrail and 45.2% (n=1313) were robust. The prevalence of frailty increased with age in both sexes; in the group aged 70–74 years, 1.8% of men and 3.7% of women were frail, whereas in the 80–84 years age group, 14.9% of men and 16.7% of women were frail. Women tended to exhibit a higher prevalence of frailty than men in all age groups.Future plansThe KFACS plans to identify outcomes and risk factors associated with frailty by conducting a 10-year cohort study, with a follow-up every 2 years, using 3014 baseline participants.
An electromagnetic pulse (EMP) with high energy can damage electronic equipment instantly within a wide range of thousands of kilometers. Generally, a metal plate placed inside a thick concrete wall ...is used against an EMP, but it is not suitable for an EMP shielding window, which requires not only strong shielding effectiveness (SE) but also optical transparency (OT). In this paper, we propose a very thin and optically transparent structure with excellent SE for EMP shielding window application. The proposed structure consists of a saltwater layer held between two glass substrates and two metal mesh layers on the outside of the glass, with a total thickness of less than 1.5 cm. The SE and OT of the structure are above 80 dB and 45%, respectively, which not only meet the requirement of EMP shielding for military purposes but also retain the procedure of good observation. Moreover, the OT of the structure can be significantly improved using only one metal mesh film (MMF) layer, while the SE is still maintained high to satisfy the required SE for home applicants. With the major advantages of low cost, optical transparency, strong SE, and flexible performance, the proposed structure can be considered a good solution for transparent EMP shielding windows.
Muscle weakness is linked to a range of adverse health outcomes across the lifespan including mortality, morbidity, and disability. Because lifestyles and body composition are quite different between ...Western and Asian countries, there is an urgent need to establish normative grip strength values for individuals of Asian descent. This study presents normative data for hand grip strength in a Korean population-representative sample.
A sample of 11,073 individuals (age 10-80 years) was included from the Sixth Korea National Health and Nutrition Examination Survey, 2014-2015. Isometric grip strength was assessed using a handheld dynamometer. Relative grip strength was calculated as the maximum absolute grip strength divided by body mass index. Means, standard error, and quintiles for grip strength and relative grip strength were analyzed per 5-year age group for each sex. To create growth charts for grip strength and relative grip strength, parametric quantile regression was used.
In males, absolute grip strength increased quickly starting from 10 years of age until approximately 20 years of age. In females, there was gradual growth until approximately 15 years of age. Grip strength continued to increase until a peak between ages 30 and 39 years, and then declined from midlife onwards in both sexes. Our data showed that the prevalence of weak grip strength increased rapidly in late adult life based on a T-score of -2 standard deviations below the sex-specific peak mean (equivalent to 33 kg in males and 20 kg in females). Approximately 20% of subjects had weak grip strength at age 65-69 years.
This was the first study to establish normative reference values for grip strength across the lifespan in a Korean population aged 10-80 years. Percentiles of grip strength will inform clinical assessments and will help identify thresholds for the identification of muscle weakness.
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