Validation of the Construct of Intrinsic Capacity in a Longitudinal Chinese Cohort.

OBJECTIVES: We examined the structure and predictive ability of intrinsic capacity in a cohort of Chinese older adults. METHODS: We used data from the MrOS and MsOS (Hong Kong) study, which was designed to examine the determinants of osteoporotic fractures and health in older Chinese adults. We analysed baseline and the 7-year follow-up data using exploratory factor analysis, confirmatory factor analysis (CFA), and mediation analysis. RESULTS: The study consisted of 3736 participants at baseline (mean 72.2 years), with 1475 in the 7-year follow-up. Bi-factor CFA revealed five sub-factors labelled as 'cognitive', 'locomotor', 'vitality', 'sensory', and 'psychological' and one general factor labelled as 'intrinsic capacity'. The model fits the data well, with Root Mean Square Error of Approximation (RMSEA)=0.055 (90% CI=0.053-0.058) for the 5-factor model and RMSEA=0.031 (90% CI=0.028-0.035) for the bi-factor model. Significantly lower intrinsic capacity scores were found in older age groups, women, as well as those who had lower levels of education, lower subjective social status, reported more chronic diseases, or a higher number of IADL limitations (All p<0.0001). Intrinsic capacity had a direct effect in predicting incident IADL limitations at the 7-year follow-up (ß=-0.21, p<0.001). The effect was larger than the direct effect of the number of chronic diseases on incident IADL limitations (ß=0.05, not significant). CONCLUSIONS: This study supports the construct and predictive validity of the proposed capacity domains of intrinsic capacity. The findings could inform the development of an intrinsic capacity score that would facilitate implementation of the concept of intrinsic capacity in clinical practice.

Effects of Protein, Essential Amino Acids, B-Hydroxy B-Methylbutyrate, Creatine, Dehydroepiandrosterone and Fatty Acid Supplementation on Muscle Mass, Muscle Strength and Physical Performance in Older People Aged 60 Years and Over. A Systematic Review on the Literature.

OBJECTIVES: The objective of this study was to perform a systematic review to investigate the effects protein, essential amino acids (EAA), ß-hydroxy ß-methylbutyrate (HMB), creatine, dehydroepiandrosterone (DHEA) and fatty acid supplementation on muscle mass, muscle strength and physical performance of elderly subjects. METHODS: Using the electronic databases MEDLINE and EMBASE we identified RCTs published until February 2016 which assessed the effects of these nutrient supplementation on muscle strength, muscle mass or physical performance. Study selection and data extraction were performed by two independent reviewers. RESULTS: Search strategy allowed us to identify 23 RCTs. Among them, four used proteins as nutritional supplement, seven EAAs, six creatine, four DHEA and finally, two HMB. From our systematic review, it seems that the effects of these supplementations on muscle health are rather limited. Only consistent effects of EAA supplementation on physical performance (3 out of the 4 RCTs using EAA supplementation found significant effect of this supplementation on physical performance) and HMB supplementation on muscle mass (all the 2 identified RCTs using HMB supplementation found significant effect of this supplementation on muscle mass) have been found across studies. No consistent effects were found for the other types of dietary supplementation. Because of the important limitations in study design, inconsistency and lack of directness, the overall quality of the evidence was judged to be low or very low using the GRADE system. CONCLUSION: This systematic review showed a limited effect of nutritional supplementation on muscle mass, muscle power and physical function. Inconsistent positive effects were observed for some specific supplementations but the results only concerned one aspect of the muscle. Well designed and appropriately powered RCTs are needed to provide evidence for appropriate clinical recommendations.