Continuous positive airway pressure versus standard care for the treatment of people with mild obstructive sleep apnoea (MERGE): a multicentre, randomised controlled trial

BACKGROUND: The evidence base for the treatment of mild obstructive sleep apnoea is limited and definitions of disease severity vary. The MERGE trial investigated the clinical effectiveness of continuous positive airway pressure in patients with mild obstructive sleep apnoea. METHODS: MERGE, a multicentre, parallel, randomised controlled trial enrolled patients (≥18 years to ≤80 years) with mild obstructive sleep apnoea (apnoea-hypopnoea index [AHI] ≥5 to ≤15 events per h using either AASM 2007 or AASM 2012 scoring criteria) from 11 UK sleep centres. Participants were assigned (1:1) to either 3 months of continuous positive airway pressure plus standard care (sleep counselling), or standard care alone, by computer-generated randomisation; neither participants nor researchers were blinded. The primary outcome was a change in the score on the Short Form-36 questionnaire vitality scale in the intention-to-treat population of patients with mild obstructive sleep apnoea diagnosed using the American Academy of Sleep Medicine 2012 scoring criteria. The study is registered with ClinicalTrials.gov, NCT02699463. FINDINGS: Between Nov 28, 2016 and Feb 12, 2019, 301 patients were recruited and randomised. 233 had mild obstructive sleep apnoea using AASM 2012 criteria and were included in the intention-to-treat analysis: 115 were allocated to receive continuous positive airway pressure and 118 to receive standard care. 209 (90%) of these participants completed the trial. The vitality score significantly increased with a treatment effect of a mean of 10·0 points (95% CI 7·2-12·8; p<0·0001) after 3 months of continuous positive airway pressure, compared with standard care alone (9·2 points [6·8 to 11·6] vs -0·8 points [-3·2 to 1·5]). Using the ANCOVA last-observation-carried-forward analysis, a more conservative estimate, the vitality score also significantly increased with a treatment effect of a mean of 7·5 points (95% CI 5·3 to 9·6; p<0·0001) after 3 months of continuous positive airway pressure, compared with standard care alone (7·5 points [6·0 to 9·0] vs 0·0 points [-1·5 to 1·5]). Three serious adverse events occurred (one allocated to the continuous positive airway pressure group) and all were unrelated to the intervention. INTERPRETATION: 3 months of treatment with continuous positive airway pressure improved the quality of life in patients with mild obstructive sleep apnoea. These results highlight the need for health-care professionals and providers to consider treatment for patients with mild obstructive sleep apnoea. FUNDING: ResMed Ltd

Mild obstructive sleep apnoea in females: <i>post hoc</i> analysis of the MERGE randomised controlled trial.

BackgroundA post hoc analysis of the MERGE trial was conducted, to investigate whether sex differences are evident at the mildest end of the disease spectrum, for symptoms associated with obstructive sleep apnoea (OSA) and the response to continuous positive airway pressure (CPAP) treatment.MethodsMERGE participants with mild OSA (apnoea-hypopnoea index 5-15 events·h-1; American Academy of Sleep Medicine 2012 criteria) were randomised to either CPAP plus standard care (sleep hygiene counselling) or standard care alone for 3 months. Quality of life (QoL) was measured by questionnaires completed before and after the 3 months. This post hoc analysis of participants of the MERGE trial compared the symptom presentation, and response to CPAP, between the sexes.Results233 patients were included; 71 (30%) were female. Females were more symptomatic at baseline in all QoL questionnaires. Specifically, females had lower 36-item Short-Form Health Survey (SF-36) Vitality scores (mean±sd 39.1±10.1 versus 44.8±10.3) and higher Epworth Sleepiness Scale (ESS) scores (mean±sd 11.0±4.2 versus 9.5±4.4). Both sexes experienced snoring, but more females reported fatigue and more males reported witnessed apnoeas. All symptoms improved with CPAP for both sexes; however, females had larger improvements in SF-36 Vitality scores, which was the primary outcome of the MERGE trial (mean change 9.4 (95% CI 6.8-12.0) versus 6.0 (95% CI 4.3-7.7); p=0.034), and ESS (mean change -4.1 (95% CI -5.1- -3.0) versus -2.5 (95% CI -3.1- -1.8); p=0.015), after adjustment for baseline scores and CPAP usage.ConclusionsSex differences are apparent in patients with mild OSA. Females experience worse QoL symptoms than males at presentation to the sleep clinic; however, these improve significantly with CPAP treatment