Many older people experience declining age-related lower muscle strength and muscle mass (sarcopenia), and this can be so severe that it affects their health and quality of life. However, new research shows that biomarkers associated with senescence (ageing at the cellular level) may detect the people at greatest risk of developing sarcopenia. A researcher says that identifying such older people early can help them to more rapidly start muscle-building exercises.
More and more older people face age-related diseases and problems, with cardiovascular diseases, mental disorders and cancer being the familiar ones.
Other problems such as sarcopenia are less well known, but it can strongly affect how long people are hospitalised and how well each person copes with illness or old age in general.
“Even though the presence of sarcopenia can have such significant consequences for older people, it is unfortunately not measured systematically upon admission. With the growing number of older people, and therefore also an increasing number of older patients, we need clinical tools that enable older patients at risk to be rapidly identified. This would enable us to initiate relevant treatment and training early and effectively, both during and after an acute hospital stay,” explains a researcher behind the new study, Rikke Kamper, MSc in Exercise & Health and PhD student at the Department of Geriatrics and Palliative Care, Bispebjerg and Frederiksberg Hospital Copenhagen, Denmark.
The new study shows that testing for a specific biomarker in a simple blood test can determine older people’s risk of sarcopaenia.
This clinically relevant discovery could be used to identify people with sarcopenia more rapidly, thereby helping them to regain their muscle strength and muscle mass through targeted exercise and nutrition.
“Restoring muscle mass takes much longer than regaining or increasing muscle strength. Identifying people at risk of sarcopenia much earlier therefore has many benefits, and tools such as biomarkers and other measurements can be important,” explains another researcher behind the study, Charlotte Suetta, Consultant, Department of Geriatric & Palliative Medicine, Bispebjerg and Frederiksberg Hospital, and Professor, Department of Clinical Medicine, University of Copenhagen, Denmark.
The research has been published in the Journal of Cachexia, Sarcopenia and Muscle.
Many older people are frail
Sarcopenia and frailty leave older people both weakened and vulnerable, with some developing one of these conditions relatively early in old age and others developing one or both conditions very late.
Since the number of older people is increasing, and people live longer with several diseases, more older people will need help.
Determining who will need help and who can take care of themselves is not straightforward, and using age as an indicator is not good enough.
“The purpose of our research was to find biomarkers to identify frailty or sarcopenia among people acutely hospitalised with a medical condition such as lung disease or heart disease,” says Rikke Kamper.
Cohort study of 1,036 older people
The researchers determined the concentration of the biomarker growth differentiation factor-15 (GDF-15) among acutely hospitalised older people.
GDF-15 is linked to senescence and has previously been associated with lower muscle strength and physical performance among healthy older people. The higher the levels of plasma GDF-15, the more frail the older person is.
However, whether GDF-15 can be used as a biomarker for sarcopenia and frailty among older people within the first 24 hours of hospitalisation is not clear.
To investigate the potential, the researchers collected blood samples from 1,036 people older than 65 years hospitalised at Bispebjerg and Frederiksberg Hospital and determined the concentration of plasma GDF-15 within the first day.
The researchers also examined the participants for sarcopenia and frailty by testing their muscle strength and examining their body composition and muscle mass.
The participants averaged 78.9 years old, and 53% were women.
Clearly associated with sarcopenia and frailty
The results showed that the concentration of plasma GDF-15 was clearly associated with sarcopenia and frailty.
The results are in accordance with the researchers’ previous studies in which they examined the level of plasma GDF-15 among healthy older people and found a higher level among older people with sarcopenia.
“We could have assumed that inflammation may have affected the association between GDF-15 and sarcopenia and frailty in connection with older people acutely hospitalised for medical conditions, but this turned out not to be the case. Instead, we found the same association among sick older people as that among healthy older people, even though we controlled for acute inflammation and the presence of other chronic diseases,” notes Rikke Kamper.
Establishing cutoff concentrations
The researchers also defined cutoff concentrations for the association between GDF-15 and sarcopenia and frailty: 1541 pg/ml for sarcopenia and 2166 pg/ml for frailty.
The median concentration of GDF-15 was 2669 pg/ml.
“These clinically relevant cutoff concentrations mean that we can use this biomarker for older hospitalised people. In particular, older people for whom sarcopenia is suspected can be followed up with a blood test. This means getting them triaged more rapidly and starting relevant treatment and exercise. Even if this might not have been the main reason why the older person was hospitalised, they will be reassured that we have covered all the bases,” explains another researcher involved in the study, Hanne Nygaard, a nurse and research lead in the Department of Emergency Medicine, Bispebjerg and Frederiksberg Hospital, Copenhagen, Denmark.
