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Title: Obstructive sleep apnoea in older people
Author: McMillan, Alison
ISNI:       0000 0004 7233 099X
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2015
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Obstructive sleep apnoea (OSA) is common and the prevalence increases with age. When OSA leads to sleep disruption and excessive daytime sleepiness, it is referred to as obstructive sleep apnoea syndrome (OSAS). The aim of this thesis was to investigate the consequences of OSAS in older people (˃ 65 years) and the effect of continuous positive airway pressure (CPAP) therapy. CPAP is the treatment of choice in moderate to severe OSAS in middle aged people. However, there is a paucity of evidence on the therapeutic and economic benefits of CPAP in older people with OSAS. The two studies in this thesis aimed to address this by comparing outcomes in older people with OSAS before and after treatment with CPAP. The first study presented is the thesis is the PREDICT trial; a multicentre randomised controlled trial of CPAP in older people with OSAS. The trial studied the clinical efficacy of CPAP after 3 months, while determining the cost effectiveness of treatment over 12 months. The results of the trial showed that CPAP was an effective treatment for reducing excessive daytime sleepiness by -2.1 (95%CI -3.0 to -1.3); p < 0.001 points as measured by the Epworth sleepiness scale. CPAP also improved quality of life, with a statistically significant increase in the quality adjusted life years calculated with the SF-6D, equating to one week. The CPAP group also accrued marginally lower health care costs over 12 months compared to the group treated with best supportive care alone. Overall the economic benefit of CPAP was linked to the reduced healthcare usage offsetting the cost of the equipment. The second study presented in the thesis was a single centre randomised controlled trial to investigate the impact of CPAP on cognitive function and brain morphology in older people with minimally symptomatic OSAS after 6 months of treatment. In this study I tested the hypothesis that older patients with OSAS have cognitive impairment and corresponding brain changes which would be modifiable with treatment. The results of this study suggested older people with minimally symptomatic OSAS had normal cognitive function but impaired attention and executive function. CPAP treatment improved one aspect of attention, although memory and overall cognitive function were unchanged. The results of the brain MRI scans are not presented, and are in the process of being analysed. In conclusion the data presented in this thesis support the use of CPAP therapy in older people with excessive daytime sleepiness due to OSAS.
Supervisor: Morrell, Mary ; Simonds, Anita Sponsor: National Institute for Health Research
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral