Summary of findings 3. CPAP with expiratory pressure relief compared to fixed CPAP for adults with obstructive sleep apnoea.
| CPAP with expiratory pressure relief compared to fixed CPAP for improving usage of CPAP machines in adults with obstructive sleep apnoea | ||||||
| Patient or population: adults with a diagnosis of sleep apnoea Setting: Europe, USA, New Zealand Intervention: CPAP with expiratory pressure relief Comparison: fixed CPAP | ||||||
| Outcomes | Anticipated absolute effects* (95% CI) | Relative effect (95% CI) | № of participants (studies) | Certainty of the evidence (GRADE) | Comments | |
| Risk with fixed CPAP | Risk with CPAP with expiratory pressure relief | |||||
| Machine usage
assessed by hours/night Follow‐up: range 2 to 24 weeks |
The mean machine usage was 5.1 hours/night | MD 0.14 hours/night higher (0.07 lower to 0.35 higher) | ‐ | 609 (9 RCTs) | ⊕⊕⊝⊝ Low 1 2 | |
| Machine usage assessed by number of participants using machine for 4 or more hours per night ‐ not measured | ‐ | ‐ | ‐ | ‐ | ‐ | |
| Symptoms
assessed with ESS Follow‐up: range 4 to 24 weeks |
The mean symptoms was 7 ESS | 0.17 ESS units higher (0.26 lower to 0.60 higher) | ‐ | 515 (6 RCTs) | ⊕⊕⊕⊝ Moderate 1 | MCID of between 2 to 3 has been proposed by Patel 2018. |
| Withdrawals (parallel group trials/first arm cross‐over trials) Follow‐up: 12 weeks |
Study population | OR 0.86 (0.48 to 1.55) | 298 (2 RCTs) | ⊕⊕⊝⊝ Low 3 | ||
| 201 per 1000 | 178 per 1000 (108 to 281) | |||||
| Quality of life assessed with FOSQ: scale from 5 to 20 Follow‐up: 12 weeks |
The mean quality of life was 18.7 FOSQ units | 0.4 FOSQ units lower (1.15 lower to 0.35 higher) | ‐ | 74 (1 RCT) | ⊕⊕⊝⊝ Low 4 | MCID for FOSQ has not been confirmed; a change of 1 unit has been proposed as representing a possible meaningful change (Billings 2014). |
| AHI measured by number of events/hr Follow‐up: range 6 to 12 weeks |
The mean AHI was 5.3 events/hour | 0.24 events/hour higher (0.49 lower to 0.96 higher) | ‐ | 342 (5 RCTs) | ⊕⊕⊕⊕ High | |
| Blood pressure ‐ not measured | ‐ | ‐ | ‐ | ‐ | ‐ | |
| Adverse events (machine tolerability outcomes) Follow‐up: range 4 to 24 weeks |
No specific measures of nasal or oral symptoms were carried out in six studies providing information on tolerability outcomes. Four studies assessed treatment comfort scores but data could not be combined. None of the studies reported that there were differences between the different treatment modes. Different measures of mask leak were made by two studies with no differences reported in either 90th percentile leak or average leak. |
‐ | 577 (6 RCTs) |
⊕⊝⊝⊝ Very low 5 6 | ||
| *The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). AHI: Apnoea Hypopnoea Index; CI: confidence interval; CPAP: continuous positive airway pressure; ESS: Epworth Sleepiness Scale; FOSQ: Functional Outcomes of Sleep Questionnaire; MCID: minimal clinically important difference; MD: mean difference; OR: odds ratio; RCT: randomised controlled trial. | ||||||
| GRADE Working Group grades of evidence High certainty: we are very confident that the true effect lies close to that of the estimate of the effect. Moderate certainty: we are moderately confident in the effect estimate; the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low certainty: our confidence in the effect estimate is limited; the true effect may be substantially different from the estimate of the effect. Very low certainty: we have very little confidence in the effect estimate; the true effect is likely to be substantially different from the estimate of effect. | ||||||
1 Downgraded one level due to serious risk of bias. Uncertainty over study design from trials published as abstracts and open‐label design in other studies.
2 Downgraded one level due to serious imprecision. Confidence interval includes no difference and increase of up to 20 minutes per person per night.
3 Downgraded two levels due to very serious imprecision. Wide confidence intervals and small sample size.
4 Downgraded two levels due to very serious imprecision. Single study with small sample size.
5 Downgraded one level due to serious imprecision. Small sample size.
6 Downgraded two levels due to very serious inconsistency. Different study designs and approaches taken to capturing tolerability outcomes.