This NIHR trial found that continuous positive airway pressure for obstructive sleep apnoea in people aged 65 and over led to less daytime sleepiness and was reasonable value for money.
Obstructive sleep apnoea causes the airway to close intermittently overnight leading to daytime sleepiness. It is most common in older people, but previous studies have generally focused on middle-aged people.
NIHR commissioned the trial to address this evidence gap. The study can be considered alongside NICE guidance which recommends that the devices be offered to people with obstructive sleep apnoea who have not responded to initial treatment such as lifestyle changes.
Why was this study needed?
Obstructive sleep apnoea is a fairly common condition, affecting 2-4% of middle-aged people and up to 20% of older people. The muscle and soft tissue in the throat relax during sleep, temporarily blocking the supply of air to the lungs. This disrupts the peron’s sleep – they wake up or sleep lighter during the night – causing sleepiness in the daytime. This can increase their risk of road traffic accidents from falling asleep at the wheel. One treatment - continuous positive airway pressure (CPAP) – involves wearing a face mask that continuously pumps a small amount of pressurised air into the throat to prevent it collapsing during the night. A 2008 meta-analysis for NICE found that CPAP reduced daytime sleepiness and was cost effective in middle-aged people. However, the evidence was less clear in older people. The NIHR funded this study to measure the clinical and cost effectiveness of CPAP in older adults, aged 65 or more, with newly diagnosed obstructive sleep apnoea.
What did this study do?
The PREDICT randomised controlled trial (RCT) randomly allocated 278 people aged 65 and over, with obstructive sleep apnoea syndrome to receive either “best supportive care” only, or best supportive care with CPAP. Best supportive care was defined as advice on minimising daytime sleepiness through lifestyle changes – such as improving sleep hygiene, napping, caffeine or losing weight if appropriate. The RCT took place in 12 NHS sleep clinics across the UK. Sleep clinic staff measuring sleep outcomes were unaware of the treatment participants had received, reducing potential bias in their assessments. Data analyses were pre-specified, reducing the risk of bias at this stage.
What did it find?
- 231 participants were assessed at 3 and 12 months and included in the analysis. After three months, CPAP with best supportive care improved self-reported sleepiness by an average of 3.8 points (from 11.5 to 7.7) on a 0 to 24 sleep scale. This was a slightly larger improvement than best supportive care only, average improvement 2.0 points (from 11.4 to 9.8). A score of 11 or above indicates possible sleep apnoea, whereas a score of 10 or below is considered normal. CPAP remained the marginally better treatment by 2.0 points (95% confidence interval [CI] 2.8 to 1.2) after 12 months.
- The average annual cost was comparable between CPAP (£1,363) and best supportive care (£1,389). In the economic analysis, CPAP appeared to be a cost-effective alternative to BSC alone. CPAP decreased costs by a small amount and improved health outcomes. However, the differences in costs and health outcomes between the treatment groups were small and uncertain. The probability that CPAP would be cost-effective at the NHS threshold of £20,000 per QALY gained was 61%, using the EQ-5D scale to measure health related quality of life.
- General and disease-specific quality of life improved more in those receiving CPAP. Both groups experienced improvements in daily functions and reduced night-time urination. There was no change in incidence of road traffic accidents.
What does current guidance say on this issue?
2008 NICE guidelines recommend that people with moderate or severe obstructive sleep apnoea are offered CPAP if their sleep apnoea affects their daily life – such as falling asleep at work – and if other treatments or lifestyle changes have not been successful.
What are the implications?
PREDICT is the longest trial of CPAP specifically in older people with sleep apnoea. It provides evidence to support the application of NICE recommendations in this population, which was previously uncertain. On average, the people included in this trial had mild sleep apnoea, but it was still serious enough that they had sought treatment for it.
PREDICT found that CPAP was cost-effective but to a lesser extent than was calculated for the 2008 NICE guidance. This may be a difference between older and younger population or might be because many of the studies in NICE’s analysis compared CPAP against “do nothing”, whereas PREDICT compares it against best supportive care, which provided advice and information.
Symptoms improved more the longer CPAP was used each night, suggesting a need to ensure that patients comply and use the device for long enough each night.
McMillan A Bratton DJ, Faria R et al. A multicentre randomised controlled
trial and economic evaluation of continuous positive airway pressure for the
treatment of obstructive sleep apnoea syndrome in older people: PREDICT. Health Technol Assess 2015; 19(4).
This project was funded by the National Institute for Health Research HTA Programme (project
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sleep apnoea. London: Department of Health; updated 2015.
NICE. Continuous positive airway pressure
for the treatment of obstructive sleep apnoea/hypopnoea syndrome. TA139. London: National Institute for Health and Care
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