You don’t need to be thin to be frail
Dr Katie Sheehan is a Vancouver based physiotherapist and a recent research fellow at The Irish Longitudinal Study on Ageing. You can see her platform presentation at 11.45 on Friday 21st at the BGS Scientific Meeting.
Frailty is often thought of as a wasting disorder and, as such, is frequently considered a consequence of ageing incurred by those older adults who present as underweight. The Fried model of frailty includes reduced gait velocity, low physical activity levels, weakness, exhaustion and weight loss. But frailty isn’t the sole preserve of the thin. As people get older, muscle mass is replaced by fat and physical function deteriorates. This phenomenon offers a particular difficulty for obese older adults who have too low a muscle mass relative to their body size. This mismatch represents a substantial barrier to physical function and may help to explain the recently reported cross sectional ‘U’ shaped relationship between Body Mass Index (BMI) and frailty. This correlation suggests that those who are underweight (body mass index (BMI) < 18.5 kg.m²) and those who are obese (BMI ≥ 30 kg.m²) are more likely to present as frail.
A BMI ≥ 30 kg.m² in midlife was found to be a risk factor for frailty in later life for Finnish men. Body composition in midlife is dissimilar to that of later life. As such while a BMI ≥ 30 kg.m² during midlife is associated with the development of frailty in later life, it is unclear whether higher BMI in later life may also predispose older adults to frailty.
In The Irish Longitudinal Study on Ageing we noted that, when co-morbidity was accounted for, obesity was associated with the frailty indicators of reduced gait velocity and physical activity levels. The criterion of weight loss was negatively linked to obesity. To avoid circularity, our main analysis focused on the non-weight components of frailty. Participants with obesity, defined by a BMI ≥ 30 kg.m² or a high waist circumference, were more likely to have a higher level of frailty after adjustment for all confounders. Interestingly, obesity was also associated with higher levels of frailty two years later.
Our results build on previous research which indicates a relationship between obesity and the development of frailty in later life. As a global population we are living longer and presenting as more overweight and obese. As such these obese frail will become more common than underweight frail clinically and present a new and growing challenge to health care.
You can see Dr Sheehan's platform presentation at 11.45 on Friday 21st at the BGS Scientific Meeting.