Bob Johnson
CH.com Alumnus
 
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"Only the educated are free." -Epictetus
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Kennett Square, PA (USA)
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We have seen several postings warning about the harmful impact of sleep apnea on the heart in additin to its immediate impact on CH. Yet another.... =====================
MEDSCAPE (8/2/08)
Untreated Sleep-Disordered Breathing May Triple Risk for Mortality
August 1, 2008 — An 18-year follow-up study finds that untreated sleep-disordered breathing (SDB) increases the risk for mortality 3-fold, according to the results of a study reported in the August 1 issue of Sleep.
"...SDB is a treatable but markedly under-diagnosed condition of frequent breathing pauses during sleep," write Terry Young, PhD, from the University of Wisconsin-Madison, and colleagues. "SDB is linked to incident cardiovascular disease, stroke, and other morbidity. However, the risk of mortality with untreated SDB, determined by polysomnography screening, in the general population has not been established."
The study cohort for this 18-year mortality follow-up study was the population-based Wisconsin Sleep Cohort sample (n = 1522). Participants had baseline polysomnography to detect SDB, which was characterized by the number of apnea and hypopnea episodes per hour of sleep. Cutoff points at 5, 15, and 30 episodes per hour of sleep identified mild, moderate, and severe SDB, respectively. All-cause and cardiovascular mortality risks associated with SDB severity levels, after adjustment for potential confounding factors, were estimated with use of Cox proportional hazards regression.
After adjustment for age, sex, body mass index, and other clinical variables, the risk for all-cause mortality significantly increased with SDB severity. For severe SDB vs no SDB, the adjusted hazard ratio (HR) for all-cause mortality was 3.0 (95% confidence interval [CI], 1.4 - 6.3). When persons who had been treated with continuous positive airway pressure (CPAP; n = 126) were excluded, the adjusted HR for all-cause mortality with severe SDB vs no SDB was 3.8 (95% CI, 1.6 - 9.0), and the adjusted HR for cardiovascular mortality was 5.2 (95% CI, 1.4 - 19.2). Accounting for daytime sleepiness did not change these results.
"Our findings of a significant, high mortality risk with untreated SDB, independent of age, sex, and BMI [body mass index] underscore the need for heightened clinical recognition and treatment of SDB, indicated by frequent episodes of apnea and hypopnea, irrespective of symptoms of sleepiness," the study authors write.
Limitations of this study include lack of information on consistent CPAP use with time or effectiveness of air pressure level to prevent airway closure, lack of randomization, inability to determine how CPAP contributes to lower death rates, inability to determine how long participants had SDB before their baseline study, and cohort 95% white and all employed at recruitment.
"Although further studies are needed to quantify the proportion of mortality that could be lowered by prevention or treatment of SDB, the results of our study can be applied directly to current health care practice," the study authors conclude.
The National Institutes of Health supported this study. The study authors have disclosed no relevant financial relationships.
Sleep. 2008;31:1071-1078.
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