medwireNews: US researchers have found that use of continuous positive airway pressure (CPAP) in patients with both chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea is associated with reductions in mortality, even when used only minimally.
And the relationship showed a dose-response effect, with the greatest reductions in mortality risk seen among patients undergoing the most nightly hours of therapy.
“We were most surprised to find that any level of CPAP use in this cohort, over no use, was associated with some mortality benefit,” said lead author, Michael Stanchina from Rhode Island Hospital in Providence, in a press statement.
Stanchina’s team identified 3760 patients with a diagnosis of obstructive sleep apnea or COPD from an outpatient database between 2007 and 2010. Of these patients, 227 had both conditions, or overlap syndrome, and received CPAP. By the end of the study, 17 (7.4%) overlap patients had died.
Objective monitoring of the CPAP device over 1 to 3 months showed that each hour of CPAP use by overlap patients was associated with a 29% reduction in mortality risk, after adjusting for confounders. Each 1-year increase in age was also significantly associated with a 14% increase in mortality risk.
And, while benefits were observed for any amount of usage, those who used CPAP for more than 2 hours per night had significantly lower mortality than those who used it for less time, with the greatest survival rate observed among those with between 4 and 6 hours usage per night.
Additionally, the authors found that patients who died during the study had significantly worse compliance, with only 21.2% using CPAP for at least 4 hours per night compared with 65.9% of those who were alive at the end of the study.
Stanchina and colleagues say that their findings demonstrate that “any CPAP use may actually be good (i.e., better than nothing), but more use is likely better.”
They note that although age did not correlate with CPAP use, patients with the lowest compliance tended to be older. “These data support the notion that older patients with overlap syndrome may have an amplification of their mortality risk due to both aging itself… and to limited use of PAP therapy,” they comment in the Journal of Clinical Sleep Medicine.
Additionally, there was a small but significant correlation between Charlson index and CPAP use, indicating that increasing numbers of comorbidities is another factor that negatively affects CPAP use.
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