Approved Research

The prevalence and functional relevance of sarcopenic obesity according to different definitions in older adults in the UK Biobank, and in relation to falls and fractures.

Lay summary

Sarcopenia is a disease of low muscle quantity and strength and is typically associated with being underweight and of older age. However, sarcopenia can exist in people who are also obese - this is called sarcopenic obesity. Separately, sarcopenia and obesity can increase a person's risk of falls, certain fractures and even death. A person who has both sarcopenia and obesity may have the combined risk of both sarcopenia and obesity.

Sarcopenic obesity is usually defined by combining a measure of sarcopenia (e.g. low muscle weight, low hand-grip strength) and a measure of obesity (e.g. high fat weight, high waist circumference). However, there are many definitions of sarcopenic obesity and because of this, estimates of the number of people with sarcopenic obesity vary from 3 in 100 to 20 in 100 people. To improve the health of people with sarcopenic obesity, we need to identify the definition which best predicts their risk of outcomes such as falls and fractures.

Measures of body composition (measures of muscle, fat and bone), muscle function (e.g. measures of muscle strength and performance), self-reported questionnaires (e.g. falls and fractures) and health-record data (e.g. fractures) will be taken from the Imaging Visit (Instance 2) of the UK Biobank.

The first aim of this study is to look at the relationship between measures of sarcopenia and obesity and falls and fractures in older adults. The second aim of this study is to look at how well four definitions of sarcopenic obesity predict falls and fractures. It is estimated that this project will take up to 24 months to complete.

Falls cost the NHS about £2.3bn per year. But there is also an individual cost; falls cause distress, loss of independence and fractures. In particular, falls are a big problem for older adults with one third falling at least once per year. If that person is obese, the risk of falling is higher. If that person is sarcopenic and obese, the risk is higher still. However lack of a standard definition is limiting awareness and identification of this condition. This study will help to identify a definition of sarcopenic obesity which can be put to practical use in healthcare.

Also, the results of this study will be used in the design of a detailed study using small muscle biopsies, MRI scans and state-of-the-art gait monitoring to understand the biology of sarcopenic obesity, and so how it might be treated.