The prescription of positive airway pressure is associated with reduced all-cause mortality, according to the results of a cohort study published in JAMA Otolaryngology–Head & Neck Surgery.
The association becomes evident several years after positive airway pressure (PAP) initiation, according to the researchers. Obstructive sleep apnea (OSA) is among the top 10 modifiable cardiovascular risk factors, and is associated with increased risks of coronary artery disease, stroke, and death. PAP is the most effective treatment for OSA, but this treatment’s effect on all-cause and cardiovascular mortality is uncertain. Randomized trials have yielded inconclusive answers to this question, and evidence from observational studies has been weak.
To investigate the association between PAP prescription and mortality in patients with obesity and severe OSA, Quentin Lisan, MD, of the Paris Cardiovascular Research Center and his colleagues conducted a multicenter, population-based cohort study. The researchers examined data for 392 participants in the Sleep Heart Health Study, in which adult men and women age 40 years or older were recruited from nine population-based studies between 1995 and 1998 and followed for a mean of 11.1 years. With each participant who had been prescribed PAP, the investigators matched as many as four participants who had not been prescribed PAP, on the basis of age, sex, and apnea-hypopnea index. Of this sample, 81 patients were prescribed PAP, and 311 were not.
All participants had a clinic visit and underwent overnight polysomnography at baseline. At 2-3 years, participants had a follow-up visit or phone call, during which they were asked whether their physicians had prescribed PAP. Participants were monitored for cardiovascular and all-cause mortality.
In all, 319 of the 392 participants were men; the population’s mean age was 63 years. Patients who had received a PAP prescription had a higher body mass index and more education, compared with patients who had not received a prescription. Mean follow-up duration was 11.6 years in the PAP-prescribed group and 10.9 years in the nonprescribed group.
A total of 96 deaths occurred during follow-up: 12 in the PAP-prescribed group and 84 in the nonprescribed PAP group. The crude incidence rate of mortality was 24.7 deaths per 1,000 person-years in the nonprescribed group and 12.8 deaths per 1,000 person-years in the PAP-prescribed group. The difference in survival between the prescribed and nonprescribed groups was evident in survival curves after 6-7 years of follow-up. After adjustments for prevalent cardiovascular disease, hypertension, diabetes, body mass index, education level, smoking status, and alcohol consumption, the hazard ratio of all-cause mortality for the prescribed group was 0.38, compared with the nonprescribed group.
Dr. Lisan and his colleagues identified 27 deaths of cardiovascular origin, one of which occurred in the prescribed group. After adjusting for prevalent cardiovascular disease, the hazard ratio of cardiovascular mortality for the prescribed group was 0.06, compared with the nonprescribed group.
One reason that the reduction in mortality associated with PAP was not found in previous randomized, controlled trials could be that their mean length of follow-up was not long enough, the researchers wrote. For example, the mean length of follow-up in the SAVE trial was 3.7 years, but the survival benefit was not apparent in the present analysis until 6-7 years after treatment initiation.
These results are exploratory and require confirmation in future research, Dr. Lisan and his colleagues wrote. No information on adherence to PAP was available, and the researchers could not account for initiation and interruption of PAP therapy. Nevertheless, “prescribing PAP in patients with OSA should be pursued and encouraged, given its potential major public health implication,” they concluded.
The Sleep Heart Health Study was supported by grants from the National Institutes of Health.
Author: Erik Greb