Available evidence "mostly does not support" a link between continuous positive airway pressure therapy and long-term, clinically important outcomes for obstructive sleep apnea, according to a U.S. government agency report.
Officials working for the Agency for Healthcare Research and Quality reviewed 47 CPAP studies to try to learn if the devices affect all-cause mortality, cardiovascular disease and other outcomes.
- AHRQ's conclusion has implications for leading CPAP manufacturers Philips Respironics and ResMed, which have released materials on the link between CPAP and cardiovascular health. CMS triggered the review, suggesting the findings could affect reimbursement.
CPAP efficacy is typically assessed in terms of the effect on the apnea-hypopnea index, which indicates the severity of sleep apnea. However, evidence of the link between sleep apnea and health outcomes such as hypertension has led to interest in whether improving AHI affects other outcomes.
AHRQ attempted to determine the effect of CPAP on outcomes beyond AHI by reviewing the medical literature. The review identified 47 studies, including 12 randomized controlled trials and 13 nonrandomized comparative studies (NRCS). Reviewers said the studies used highly inconsistent criteria to define breathing measures but they gleaned enough from the data to form some conclusions.
"RCTs provide low strength of evidence that CPAP does not affect the risk of all-cause mortality, stroke, myocardial infarction or composite [cardiovascular] outcomes," AHRQ wrote. Combining the RCT and NRCS data provided low strength of evidence that CPAP reduces the risk of mortality but the agency said that finding "may be most applicable to older adults and longer-term followup."
In other areas, the evidence was too limited to form conclusions. AHRQ said the RCTs provide insufficient evidence to assess risk of cardiovascular death, although factoring in NRCS data suggests CPAP has no effect. The overall dataset is too limited to form conclusions about the effect of CPAP on risk of transient ischemic attack, angina, coronary artery revascularization, congestive heart failure and atrial fibrillation.
AHRQ said more studies of the effect of CPAP on long-term outcomes are needed. Further research could show whether breathing endpoints such as AHI are valid intermediate or surrogate measures of long-term, clinically important outcomes.
The agency is seeking feedback on its report until April 23. A spokesperson for CPAP leader ResMed said their medical affairs team "is currently reviewing the report and drafting a public comment around it" and as such "can't comment on this right now."
A Philips spokesperson also declined to comment on AHRQ's report.
CPAP is covered by Medicare's competitive bidding but CMS opted against awarding contracts in the most recent round after some bidding areas saw increases of 100%.