Sleep doctors are concerned about a draft report casting doubt on the clinical benefits of continuous positive airway pressure (CPAP), the clinical gold standard for sleep apnoea.
Reviewers from the Agency for Healthcare Research and Quality (AHRQ) 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 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 US offers coverage for CPAP therapy under Medicare for patients with OSA, amounting to hundreds of millions of dollars per annum.. One recent study of Medicare recipients 56% were at high risk for OSA and possible candidates for treatment.
“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 that it is widely recognised that CPAP is the most effective treatment for improving OSA symptoms, such as snoring and daytime sleepiness.
“Nothing else even comes close,” he said. “CPAP is 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 review included data from 47 long term (≥6 or 12 months) randomised clinical trials for OSA.
Investigators noted that the studies used “highly inconsistent” definitions of measures such as respiratory events, as well as the Apnoea-Hypopnoea Index (AHI) metric.
“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 definitions should be standardised.
“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, agreed inconsistency and poor CPAP compliance in sleep studies have made it difficult to assess its impact on mortality and most other long-term outcomes.
But he, like Dr Rapoport, expressed concern that some will interpret the findings to mean that CPAP is ineffective.
“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.”
Dr Patel served on the writing committee for the American Academy of Sleep Medicine’s (AASM) latest clinical practice guidelines for OSA treatment with CPAP. He observed that the guidelines differ from the AHRQ findings, in that CPAP has been shown to lower blood pressure in hypertensive OSA patients.
The AHRQ analysis was also restricted to 6 month follow-ups or longer, 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, Dr 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.”
Source: MedPage Today
