Treatment with continuous positive airway pressure machines does not reduce cardiovascular risk more than usual care for patients with both cardiovascular disease and obstructive sleep apnea, according to a new study which was published in the New England Journal of Medicine.
Data from the 2,717-patient study indicated that after a mean follow-up time of 3.7 years, there was no difference between the CPAP and usual-care group in terms of death from cardiovascular causes, myocardial infarction or stroke and hospitalization for heart failure, acute coronary syndrome or transient ischemic attack.
A total of 17% of the patients in the CPAP group and 15.4% in the usual-care group had serious CV events.
“Given the level of risk of cardiovascular disease attributed to OSA in previous observational studies, we were surprised not to find a benefit from CPAP treatment,” study principal investigator Dr. Doug McEvoy of Australia’s Adelaide Institute for Sleep Health at Flinders University said in a prepared statement.
Patients being treated with the CPAP machines reported mean apnea-hypopnea index scores which decreased from 29 to 3.7 events per hour, which puts them in “good control of their OSA,” according to the report.
“It’s not clear why CPAP treatment did not improve CV outcomes. It is possible that, even though the average CPAP adherence of approximately 3.3 hours per night was as expected, and more than we estimated in our power calculations, it was still insufficient to show the hypothesized level of effect on CV outcomes,” Dr. McEvoy said in a press release.
Patients on CPAP treatment did show improvements in terms of wellbeing, according to the report, as defined by symptoms of daytime sleepiness, health-related quality of life, attendance at work and mood.
“While it is disappointing not to find a reduction in CV events with CPAP treatment, our results show that treatment of OSA in patients with CV disease is nevertheless worthwhile – they are much less sleepy and depressed, and their productivity and quality of life is enhanced. More research is needed now on how to reduce the significant risk of CV events in people who suffer from sleep apnea,” Dr. McEvoy said. “Given our finding of a possible reduction in cerebrovascular events in patients who were able to use CPAP for more than 4 hours per night, and of prior studies showing a stronger association between OSA and stroke than between OSA and coronary artery disease, future trials should consider targeting patients with OSA and stroke who can achieve a high level of compliance with CPAP.”