Sleep disordered breathing has been found in four out of five healthy Australians aged over 70 years in a large cohort study and is often linked to impaired physical health-related quality of life and cognitive function.
Monash University researchers analysed data from two sleep studies – a multicentre, randomised, double-blind study and an Australian sub-study – and found 81% of the almost 1400 eligible participants had at least five episodes of oxygen desaturation and met the criteria for mild sleep apnoea. One in four had moderate symptoms.
Clinically, however, the sleep disordered breathing was not associated with daytime sleepiness, depression or quality of life concerning mental health.
The results, published in Respirology, suggested treatment decisions should focus on people experiencing the clinical indicators, given the high prevalence of obstructive sleep apnoea.
“This study has confirmed the ubiquitous nature of [sleep-disordered breathing] in older age, demonstrated an association with reduced cognitive function and has shown that sleep-disordered breathing as measured by the [oxygen desaturation index] is associated with reduced physical health [quality of life],” the authors wrote.
“For this age group, in which sleep-disordered breathing is so common, quality of life and cognitive assessments may best guide treatment decisions and targets for sleep-disordered breathing, especially as treatment of sleep-disordered breathing has been shown to improve quality of life in older age,” they added.
The study conducted cross-sectional analysis of data from the Australian-US ASPREE and Australian SNOREASA sub-study in a bid to assess the clinical impact of sleep-disordered breathing for older people.
It found 80.7% of participants had oxygen desaturation index of equal to or greater than 5.
“Given that the ‘normal’ cut-off of an ODI of ≥5 was exceeded by over 80% of this relatively healthy cohort, the results suggest that SDB may even be expected as part of normal ageing,” the study authors said.
Severe sleep-disordered breathing was experienced by 6.9% of subjects and 24.3% had moderate symptoms.
“For this age group, in which SDB is so common, QOL and cognitive assessments may best guide treatment decisions and targets for SDB, especially as treatment of SDB has been shown to improve QOL in older age,” the researchers suggested.
Respiratory and Sleep Physician Associate Professor Garun Hamilton, one of the co-authors of the paper, said the study highlighted how common obstructive sleep apnoea was in the aged population.
“This is the first study to show the Australian prevalence of OSA [obstructive sleep apnoea] in such a large community elderly population,” said Professor Hamilton, Director of Sleep Research at Monash Health.
“What is unclear is at what level of sleep disordered breathing is this an almost normal part of ageing versus something that is pathological? It is likely that we need to shift definitions of OSA according to age and perhaps co-morbidities, and consider OSA as a continuum that changes in significance across the age and co-morbidity spectrum, like the way we consider blood pressure.”
He said the clinical presentation of lower quality of life and cognitive function, and the lack of daytime sleepiness, was consistent with other cohort studies, however the results were stronger than expected for mild sleep apnoea.
“It is important to note however, that these are cross sectional associations and do not prove causation. We need to wait for the longitudinal follow up data to assess this more specifically,” he said.
He said decisions on how to treat older people with OSA relied on a comprehensive qualitative assessment, given the challenges with adherence to the CPAP treatment.