Frailty and Sarcopenia in Older Patients Receiving Kidney Transplantation

Abstract

Kidney transplantation is the treatment of choice for most of the patients with end-stage renal disease (ESRD). It improves quality of life, life expectancy, and has a lower financial burden to the healthcare system in comparison to dialysis. Every year more and more older patients are included in the kidney transplant waitlist. Within this patient population, transplanted subjects have better survival and quality of life as compared to those on dialysis. It is therefore crucial to select older patients who may benefit from renal transplantation, as well as those particularly at risk for post-transplant complications. Sarcopenia and frailty are frequently neglected in the evaluation of kidney transplant candidates. Both conditions are interrelated complex geriatric syndromes that are linked to disability, aging, comorbidities, increased mortality, and graft failure post-transplantation. Chronic kidney disease (CKD) and more importantly ESRD are characterized by multiple metabolic complications that contribute for the development of sarcopenia and frailty. In particular, anorexia, metabolic acidosis and chronic low-grade inflammation are the main contributors to the development of sarcopenia, a key component in frail transplant candidates and recipients. Both frailty and sarcopenia are considered to be reversible. Frail patients respond well to multiprofessional interventions that focus on the patients' positive frailty criteria, while physical rehabilitation and oral supplementation may improve sarcopenia. Prospective studies are still needed to evaluate the utility of formally measuring frailty and sarcopenia in the older candidates to renal transplantation as part of the transplant evaluation process.

Keywords: disability; elderly; frailty; kidney transplant; malnutrition; sarcopenia.

Figure 1

The cycle of frailty (45). The four key factors of frailty (in the central circle) are sarcopenia, lower resting metabolic rate, lower energy expenditure, and chronic undernutrition. These factors are interconnected and amplifying the process and it is hard to distinguish the first factor that started it. In the peripheral area are represented the contributors to these factors. The main contributors to sarcopenia are weight loss (through protein and micronutrient deficit and increased catabolism), musculoskeletal senescence and various diseases. Sarcopenia itself, through the reduction of muscle strength and power, provokes one of the key features of the frailty assessment: the reduced walking speed. The diaphragm and visceral muscle sarcopenia along with anemia are responsible for reduced oxygen uptake (VO₂) and subsequent exhaustion, which contribute in slowing the walking speed. Reduced walking speed is associated with lower physical activity and subsequent lower energy expenditure. In some cases, the marked reduced walking capacity can configure a disability with loss of independency and need for assistance. Neuroendocrine dysregulation, frequently observed in older people, can reduce the appetite (anorexia of aging) and contribute to chronic undernutrition along with the lower energy expenditure with subsequent weight loss. A mild and chronic inflammation can have a negative impact in these processes. VO₂, oxygen uptake.

Figure 2

Algorithm to identify cases of sarcopenia in transplant candidates and recipients [adapted from (89)].