Approved Research

Bioimpedance defined lean tissue mass in chronic kidney disease: its relationship to comorbidity, mortality and surrogate markers of frailty.

Lay summary

Many long-term health conditions lead to progressive loss of muscle bulk, usually referred to as lean tissue mass (LTM). This loss of muscle bulk can be particularly severe in people with chronic kidney disease, contributing to the most important symptom experienced by these patients: fatigue. Bioimpedance is an established method which safely estimates the muscle bulk in a patient at the bedside. Questions remain, however, as to whether there is value in measuring muscle bulk routinely and how it should be interpreted in clinical practice. We principally still do not know: (1) "how much is loss of muscle bulk explained by reduced kidney function compared to the effects of other long term health conditions?" and (2) "To what extent does the loss of muscle bulk explain how likely it is for patients to die, suffer from adverse events (such as falls) and symptoms attributable to frailty, such as fatigue, in patients with chronic kidney disease?".

To investigate these questions we will use data collected by the UK Biobank, a long-term study of half a million people of whom 50,000 have one or more long-term health condition.  Muscle bulk was measured using bioimpedance when patients entered the study. What happened to these patients was subsequently recorded throughout the study. We will use a novel statistical approach to understand how long-term health conditions and the level of kidney function in turn affect muscle bulk in patients with different demographic characteristics. This will enable us to describe whether these factors act on a patients muscle bulk, and how this relates to their symptom burden, health-related outcomes and the risk of death.

Our research findings will inform clinicians how best to interpret bioimpedance data measuring reduced muscle bulk by understanding: (1) how loss of muscle bulk is influenced by other long-term health conditions and (2) the relative importance of losses in muscle bulk in the development of adverse events and symptoms.  It is likely this research will reinforce the need to take a more personalised approach to clinical decision making where treatment goals may be influenced by the presence of other long-term health conditions. Our findings will be disseminated to patients and other relevant stakeholders, multidisciplinary conferences to healthcare professionals who work with patients with multiple long term health conditions, including chronic kidney disease, and by publication in peer reviewed scientific journals.