Continuous positive airway pressure

Vol 64: OCTOBER | OCTOBRE 2018 |

745 É D I T O R I A L

T O O L S F O R P R A C T I C E

Continuous positive airway pressure

Peter (Ran) Yang

Christina Korownyk

Clinical question

Does continuous positive airway pressure (CPAP) reduce cardiovascular disease (CVD) or mortality in patients with obstructive sleep apnea (OSA)?

Bottom line

There is a lack of convincing evidence that CPAP reduces CVD or mortality in patients with moderate to severe OSA. Adherence to CPAP treatment in most clinical trials is low (1.4 to 5.8 hours per night at 1 year). Modest clinically important improvements in daytime sleepiness have been demonstrated. Quality- of-life scales have also demonstrated improvement, although the clinical signifcance is unclear.

Evidence

Three meta-analyses of RCTs have been completed.

Most patients were male, with a mean age older than 60 years and moderate to severe OSA.

• There was no statistical difference in outcomes for CPAP versus standard care or sham.

-Cardiovascular disease

: 7% with CPAP versus 8% of controls (7 trials, 4562 patients).

-Cardiovascular death

: 9% with CPAP versus 8% of controls (7 trials, 5476 patients).

-Acute coronary syndrome

: 3% with CPAP versus 3%

of controls (7 trials, 4562 patients).

-Stroke

: 4% with CPAP versus 4% of controls (6 trials, 4171 patients).

• Post hoc analysis did not identify any signifcant rela- tionship between CPAP and CVD regardless of apnea severity, length of follow-up, or adherence.

• Limitations: Studies were somewhat heterogeneous, with inclusion of central apnea patients in some outcomes and differences in length of follow-up (2 to 68 months) and adherence to CPAP (1.4 to 5.8 hours a night at 1 year).

Context

• Obstructive sleep apnea is associated with increased risk of CVD and mortality.

• Use of CPAP modestly improves daytime sleepiness by 1.6 to 3.8 points on a 24-point scale, which is likely clini-

cally detectable.

• Use of CPAP is associated with modest improvements in quality-of-life measures (eg, about a 3.3- to 9.7- point improvement on a 100-point scale)

with uncer- tain clinical relevance.

• Use of CPAP signifcantly decreases blood pressure (mean reduction of 2.5 mm Hg systolic and 2.0 mm Hg diastolic, P < .001).

• Observational data suggest CPAP use significantly reduces motor vehicle accidents (P<.001).

A large RCT (2717 patients) reports a non–statistically significant trend toward injury reduction (7.4% vs 8.8%, P=.06).

Implementation

Laboratory polysomnography (level I study) is the criterion standard for diagnosing OSA.

If access is a barrier, home apnea testing (level III study) can be considered for symp- tomatic patients with a high pretest probability of OSA.

A trial of CPAP might demonstrate beneft in symptom- atic patients, although cost can be a barrier.

A systematic review and meta-analysis of 4 small trials found that exer- cise training demonstrated similar improvement in clini- cally important outcomes in patients with OSA (eg, about a 3.1-point improvement on a sleepiness scale out of 24).

While interventions were diverse, they typically included aerobic and resistance exercise 3 to 4 times per week.

Mr Yang is a medical student at the University of Alberta in Edmonton. Dr Korownyk is Associate Professor of the PEER (Patients, Experience, Evidence, Research) group in the Department of Family Medicine at the University of Alberta.

Competing interests None declared

The opinions expressed in Tools for Practice articles are those of the authors and do not nec- essarily mirror the perspective and policy of the Alberta College of Family Physicians.

References

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Tools for Practice articles in Canadian Family Physician are adapted from articles published on the Alberta College of Family Physicians (ACFP) website, summarizing medical evidence with a focus on topical issues and practice-modifying information. The ACFP summaries and the series in Canadian Family Physician are coordinated by Dr G. Michael Allan, and the summaries are co-authored by at least 1 practising family physician and are peer reviewed. Feedback is welcome and can be sent to toolsforpractice@cfpc.ca. Archived articles are available on the ACFP website: www.acfp.ca.