Sleep medicine specialists are worried about a draft technology assessment from the Agency for Healthcare Research and Quality (AHRQ) that casts doubt on the long-term clinical benefit for the gold standard treatment for sleep apnea.
Reviewers found that studies of continuous positive airway pressure (CPAP) have consistently failed to show improvements in non-sleep-related outcomes linked to obstructive sleep apnea (OSA), such as stroke, heart attack, diabetes, and depression.
The report -- and through April 23 -- concluded that the published evidence "mostly does not support that CPAP prescription affects long-term, clinically important outcomes," and it highlighted research gaps and methodological weaknesses in the available studies, along with significant CPAP compliance issues, which have all contributed to the failure to show long-term benefits for the treatment.
OSA specialists who spoke to MedPage Today about AHRQ's research review agreed that CPAP remains by far the most effective treatment for sleep-related symptoms of OSA. They worried that the report could be misinterpreted as meaning that the treatment has no value.
The research review was requested by CMS; Medicare covers 80% of a 3-month trial of CPAP for beneficiaries with a diagnosis of OSA, with continued coverage based on treatment compliance.
One found that more than half (56%) were at high risk for OSA and possible candidates for treatment. Total Medicare spending on CPAP amounts to hundreds of millions of dollars annually.
"The big fear that I have, and many of my colleagues have, is that the way this report is worded could easily be misinterpreted as saying that prescribing CPAP doesn't improve these (long-term) outcomes, so we shouldn't be paying for it," said David Rapoport, MD, who directs the sleep medicine research program at the Icahn School of Medicine at Mount Sinai in New York City.
He said CPAP is widely recognized as the most effective treatment for improving OSA symptoms, such as snoring and daytime sleepiness.
"Nothing else even comes close," he said. "CPAP s really a remarkable treatment for addressing the breathing disorder associated with obstructive sleep apnea. But it has to be used, and compliance remains a big issue."
The AHRQ's Evidence-based Practice Centers (EPC) included data from 47 randomized clinical trials and other studies in their analysis reporting long-term (≥6 or 12 months) clinical outcomes in adult patients with OSA.
Investigators noted that the studies used "highly inconsistent" definitions of breathing measures, respiratory events, and response to treatment, measured using the Apnea-Hypopnea Index (AHI) -- a metric that the report also critiqued.
"No standard definition of this measure exists and whether AHI (and associated measures) are valid surrogate measures of clinical outcomes is unknown," the report states.
Elise Berliner, PhD, of AHRQ, told MedPage Today that addressing the inconsistencies and limitations of the existing studies should be a top priority of the sleep research community.
She added that while the report does not address whether CPAP is overprescribed, it does call on the sleep research community to improve study designs by standardizing key measures such as AHI, CPAP compliance, and the definition of severe OSA.
"I do think the community needs to get together and figure out how to do better studies," she said. "We need larger and longer studies, and there is also the issue of compliance. In most of the studies, people were not using these devices all night long."
The report found that the existing randomized controlled trials provide low strength of evidence that CPAP affects all-cause mortality, stroke and myocardial infarction risk, or other cardiovascular outcomes. Researchers also concluded that insufficient evidence exists showing an impact for CPAP on the risk for automobile accidents, depression, and anxiety and hypertension.
Sanjay Patel, MD, of the University of Pittsburgh, agrees that lack of consistency and poor CPAP compliance in sleep studies have made it difficult to assess the treatment's impact on mortality and most other long-term outcomes.
But like Rapoport, he expressed concern that the draft report findings will be interpreted by some as suggesting that CPAP is an ineffective treatment.
"The thinking in the field has been that treatment may help prevent diseases like diabetes and heart disease that are related to sleep apnea," he told MedPage Today. "This report says we don't have good evidence on this, but it doesn't really distinguish between outcomes where we do and do not have enough research to say definitively that treatment with CPAP isn't beneficial."
Patel served on the writing committee for the American Academy of Sleep Medicine's on the treatment of adults with OSA using positive airway pressure, which was published in 2019.
He noted that the updated guidelines differ from the AHRQ report in one key area, concluding that CPAP has been shown to lower blood pressure in OSA patients with comorbid hypertension.
The AHRQ analysis was restricted to people who were followed for more than 6 months, while the AASM's writing committee considered studies with shorter follow-up times.
"The effect [of CPAP] on blood pressure can be seen at 1 month," he said. "Multiple studies with 3 months of follow-up show improvements in blood pressure, but AHRQ did not look at those studies."
While CPAP is still considered the most effective treatment for OSA, Rapoport said there is a growing recognition within the sleep medicine field that it's not for everyone, given the ongoing issues with compliance.
"In the past, other treatments such as mandibular advancement devices have been marginalized," he said. "These treatments don't work nearly as well as CPAP in terms of lowering AHI, but they do work well for many patients, and people who are prescribed them actually use them. Until recently, there wasn't much acceptance that this was good enough. But there is now greater recognition that we should maybe be prescribing treatments that aren't perfect if people are more likely to use them."
Disclosures
The AHRQ Evidence-based Practice Centers investigators reported no relevant conflicts.
David Rapoport, who commented on the report, cited financial ties to the CPAP manufacturer Fischer and Paykel.