Study links frailty risk with obesity

Morgan Liotta

24/01/2023 4:49:31 PM

Routine assessment of BMI is a fundamental part of reducing the risk of frailty in older age, according to both new research and a local expert.

Older frail person's hand
Over a 21-year monitoring period, people with obesity were assessed for risk of frailty later in life.

According to the RACGP aged care clinical guide (Silver Book), frailty is ‘a syndrome of physiological decline that occurs in later life’, and is associated with ‘vulnerability to adverse health outcomes’ – but age alone ‘does not define frailty, and frailty is not an inevitable consequence of ageing’.
Declared a medical condition in 2019, frailty is best assessed annually using a validated measurement tool, the RACGP recommends.
And while undernutrition is among the factors associated with increased frailty, the Silver Book also identifies that obesity may be a factor due to its contribution to a ‘pro-inflammatory state’.
That theory is also supported by newly published research from Norway, which suggests that being overweight from mid-life onwards is linked to a heightened risk of physical frailty in older age.
Using body mass index (BMI) and waist circumference, the study investigated the association between obesity, pre-frailty and frailty among 4509 people aged 45 and older from 1994−2016 in the Norwegian city of Tromsø.
Those people who had obesity in 1994 were almost 2.5 times as likely to be ‘pre-frail or frail’ by 2016 than those with a normal BMI.
A BMI of less than 18.5 was categorised as ‘underweight’, a BMI of 18.5–24.9 as ‘normal’, and 25–29.9 as ‘overweight’. A BMI of 30 and above was classed as obesity.
The authors highlight that as both ‘general and abdominal’ obesity, especially over time during adulthood, are associated with an increased risk of pre-frailty and frailty in later life, that routine assessment and maintaining optimal BMI and waist circumference throughout adulthood are important to reduce frailty risk.
Assessment and management of overweight and obesity in primary care require a personalised, non-judgemental approach, according to the RACGP, and the Australian Diabetes Society recently developed an algorithm for the management of obesity in this setting.
Dr Terri-Lynne South, Chair of RACGP Specific Interests Obesity Management, told newsGP that as part of that care GPs should be aware of the reasons behind frailty, such as age-related loss of lean body mass, particularly muscle mass.
‘There are simple ways for us to screen for this in general practice, including grip strength, as well as simple things like the sit-to-stand test: how many times the patient can go from sitting in a chair to standing over a minute,’ she said.
‘We can use those as cut offs, but also serial markers over 20 years … which is what is talked about and linked to in the [Tromsø] study.’
Frailty is defined in the study as the presence of at least three or more – and ‘pre-frailty’ as the presence of one to two – of the following five criteria:

  • low-grip strength
  • slow walking speed
  • exhaustion
  • unintentional weight loss
  • low physical activity.
Grip strength, cited as a biomarker for muscle strength in older adults, was found to be associated with baseline overweight and obesity assessed using BMI in the study.
Based on World Health Organization guidelines, the study defined a waist circumference of ≤94 cm for men and ≤80 cm for women as ‘normal’, and ‘high’ for men with >102 cm and women with >88 cm.
Those with a ‘moderately high’ waist circumference at the beginning of the study monitoring period were 57% more likely to be pre-frail or frail than those with a ‘normal’ waistline, while those recorded with a ‘high’ waist circumference were twice as likely to fall into the frail categories.
Aligning with previous research, the Tromsø study’s findings of the link between mid-life overweight or obesity and the development of pre-frailty and frailty in later life is potentially due to the ‘aggravation of the age-related decline in muscle strength, aerobic capacity and physical function’.
The increased inflammatory capacity of fat cells and their infiltration into muscle cells, which can enhance naturally occurring age-related decline in muscle mass and strength, also plays a role.
Dr South believes it is important to understand that if someone is retaining their body weight, they are not necessarily retaining their lean muscle mass.
‘We know that we tend to gain weight after the “middle-age spread” and beyond until age 65, and then we can start to lose weight, but in that middle age, we’re actually gaining fat tissue and losing lean body mass,’ she said.
‘Then in the more elderly, they’re losing preferentially lean body mass. So that’s what frailty comes down to – it’s really that muscle mass in our bodies – and weight per se, is not the best marker of muscle mass.’
Obesity can lead to increased fat mass and lipid infiltration in muscle fibres, the Tromsø study states, resulting in reduced muscle strength and function.
‘When coupled with an age-related decline in muscle mass and strength, it causes “sarcopenic obesity”, which is linked to an increased risk of frailty and disability,’ the authors write.
However, the authors caution that these links should be interpreted carefully, as few studies have tracked long-term weight changes and frailty risk, and this type of study cannot ascertain that mid-life overweight or obesity causes frailty.
The study also accounted for co-existing conditions such as diabetes and lifestyle factors such as alcohol intake, smoking and physical activity when determining results for ‘strong’ and ‘pre-frail/frail’ groups.
They also emphasised that with rapidly ageing populations and rising obesity epidemics, their research adds to evidence moving away from viewing frailty ‘only as a wasting disorder’.
Dr South agrees.

‘Frailty is not just cognitive, it’s physical as well as related to medications or medical conditions,’ she said.

‘It’s something that GPs really need to embrace … the percentage of patients that are considered older is increasing, so it’s going to become a higher and higher priority.’
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