Phase Angle as Surrogate Marker of Muscle Weakness in Kidney Transplant Candidates Referred to Prehabilitation.

Phase angle (PhA), a marker of nutritional status obtained by bioelectrical impedance analysis (BIA), is associated with the integrity of cell membranes. Damage to muscle fiber membranes can impact muscle strength, which is related to adverse outcomes in adults with advanced chronic kidney disease (CKD). The main objective of this study was to determine the usefulness of the PhA in identifying muscle weakness in candidates for kidney transplants (KTs). Secondly, it aimed to examine the associations of PhA with other parameters of body composition, exercise performance, and muscle structure. Sensitivity, specificity, and area under the receiver operating characteristics curve were used to evaluate the PhA (index test) as a biomarker of muscle weakness. Muscle strength was estimated with maximal voluntary isometric contraction of the quadriceps (MVCI-Q) of the dominant side. Muscle weakness was defined as MVIC-Q < 40% of body weight. A total of 119 patients were evaluated (mean age 63.7 years, 75.6% men). A phase angle cut-off of 5.1° was identified to classify men with a higher likelihood of having low muscle strength in upper limbs (MVIC-Q 40% of their body weight). Male KT candidates with PhA < 5.1° had poorer exercise capacity, lower muscle strength, less muscle mass, and smaller muscle size. A PhA < 5.1° was significantly associated with an eight-fold higher muscle weakness risk (OR = 8.2, 95%CI 2.3-29.2) in a binary regression model adjusted by age, frailty, and hydration status. Remarkably, PhA is an easily obtainable objective parameter in CKD patients, requiring no volitional effort from the individual. The associations of PhA with aerobic capacity, physical activity, muscle mass, and muscle size underscore its clinical relevance and potential utility in the comprehensive evaluation of these patients.

New perspectives on frailty in light of the Global Leadership Initiative on Malnutrition, the Global Leadership Initiative on Sarcopenia, and the WHO's concept of intrinsic capacity: A narrative review.

This review gathered the evidence on the epidemiology of frailty, as well as on screening and diagnostic tools, and new perspectives, in light of the latest global frameworks in malnutrition, sarcopenia, and the World Health Organization's concept of intrinsic capacity. Frailty is a worldwide health challenge and highly prevalent in older adults and the population with chronic diseases independent of age. Regardless of the particular concept of frailty, many screening and diagnostic tools are able to identify frailty in older people, but none of them has shown superiority in every population and healthcare setting. Physical, cognitive, and social components are part of the larger context of frailty. The latest evidence-based initiatives on frailty recommend the use of validated tools to identify frailty's different components, tailored to the needs of specific populations and healthcare systems. Unintentional weight loss is a shared criterion between physical frailty and malnutrition according to the Global Leadership Initiative on Malnutrition criteria. A new definition of sarcopenia by the Global Leadership Initiative on Sarcopenia is awaited, but at present physical frailty shares with sarcopenia the criteria of low muscle function and physical performance (severity grading) according to the revised consensus of the European Working Group on Sarcopenia in Older People (EWGSOP2). The EWGSOP2 includes both muscle mass and function, with most scientific groups agreeing that function is a key hallmark of sarcopenia. The concept of intrinsic capacity features the reserves and positive aspects of aging, and responds to ageism by addressing the deficit model approach. Intrinsic capacity is an emerging, person-centered and public health indicator, aimed at preserving health at mid-life and beyond, to move towards a better aging process in the Decade of Healthy Aging 2020-2030.