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(Reuters Health) - Although having sleep apnea has been linked to elevated risk of heart disease, high blood pressure and stroke, a new analysis of past research finds that apnea treatment with positive airway pressure (PAP) does not reduce the risk of cardiovascular events or death.
"Doctors need to be aware that while PAP may provide symptomatic relief for sleep apnea, it is unlikely to provide protection against cardiovascular events or death,” the study's senior author Bruce Neal from UNSW Sydney in Australia told Reuters Health by email.
PAP is commonly used to treat sleep apnea, but it remains unclear whether PAP alters the risk of vascular disease and death in these patients, the study team writes in JAMA.
Neal's team analyzed data on adults with sleep apnea from 10 randomized clinical trials that included a total of 7,266 patients.
In these trials, PAP was not significantly associated with major adverse cardiovascular events such as heart attack, major adverse cardiovascular events plus hospitalization for unstable angina, cardiovascular death, all-cause death, non-cardiovascular death, acute coronary syndrome, stroke, hospitalization for unstable angina or heart failure.
Four trials did hint that people who used PAP at least four hours per night might have improved cardiovascular outcomes, but the results didn't reach a statistically meaningful threshold.
“Two points here: first, while it’s an intuitively appealing finding, it is statistically rather weak,” Neal said. “Second, good adherence is hard to achieve with current therapeutic options for PAP. If a new, very well-tolerated mode of PAP therapy is identified, it would be really helpful to do a large outcome trial to try and confirm this tantalizing observation.”
While PAP did not improve blood pressure, body mass index, blood lipids, blood sugar or overall quality of life, it was associated with improvements in sleepiness and some measures of physical and mental wellbeing.
"Based on the available evidence," the researchers conclude, "it is reasonable to recommend PAP therapy for the improvement of symptoms in patients with obstructive sleep apnea (OSA) but not for protection against vascular disease or death."
“Patients with sleep apnea, who are often at increased cardiovascular risk, need rigorous management with other indicated therapies, such as blood pressure lowering, statins, and antithrombotic drugs,” Neal said.
"I think the most interesting finding of the meta-analysis is that the best estimate of the effect of obstructive sleep apnea treatment on risk of major adverse cardiovascular events is very similar to the reduction in risk seen with aspirin, beta-blockers, or statin medications," said Dr. Daniel J. Gottlieb from VA Boston Healthcare System and Harvard Medical School, who wrote an accompanying editorial.
"That this was not statistically significant reflects the small number of patients entered in clinical trials up to this point,” he told Reuters Health by email.
“I don't think these findings should have a major impact on CPAP prescribing,” Gottlieb said. “The main reason for treatment of CPAP remains control of symptoms, especially excessive sleepiness. Whether treatment of OSA will reduce cardiovascular risk remains an unanswered question.”
Most studies included in this analysis showed that patients are not using their CPAP machine as long as they should, noted Dr. Haitham Al Ashry from The Medical University of South Carolina in Charleston, which may explain the study results.
"However, when authors looked at patients who wore their CPAP more than four hours, they found decreased risk of death, heart attacks, and stroke, which is in concert with a similar analysis we published recently in the American Journal of Cardiology,” he told Reuters Health by email.
“I think physicians should continue to do their due diligence in counseling patients about the importance of adherence to CPAP,” Al Ashry said. “It is clear from this paper that cardiovascular benefits may be lost if CPAP is worn less than four hours. This is consistent with Medicare criteria that define patients’ compliance with CPAP as wearing the machine at least four hours each night for 70 percent of the nights.”