Severe breathing disorders during sleep are associated with an increased
risk of dying from any cause according to research published this week in
the
open access journal PLoS Medicine. The study finds that the increased risk
of dying is most apparent in men between 40 and 70 years of age with
severe
sleep-disordered breathing, and suggests a specific link between this
condition and death from coronary heart disease in men.
Sleep-disordered breathing is characterized by a collapse of the upper
airway during sleep, leading to numerous, brief interruptions of breathing
known as sleep apnea, and it is experienced by one in four men and one in
ten women. Although it is increasingly recognised as a serious
condition-linked with hypertension, heart failure and stroke, as well as
causing daytime sleepiness with dangerous consequences such as impairing a
person's ability to drive safely-previous studies investigating
sleep-disordered breathing have not included participants in sufficient
numbers to
identify specific factors (such as age and sex) that might predict an
increased risk of dying.
In the Sleep Heart Health Study, Naresh Punjabi of Johns Hopkins
University, Baltimore and colleagues studied over 6,000 men and women,
initially
assessing their night-time breathing, sleep patterns and blood oxygen
levels, and calculating each participant's apnea-hypopnea index (AHI),
defined
as the number of pauses in breathing severe enough to cause a 4% drop in
blood oxygen saturation, per hour of sleep. Following the study
participants
over an average of 8 years, they found that those with severe sleep
disordered breathing (AHI of 30 or above) at the outset were one and a
half times
more likely to die from any cause, irrespective of age, sex, race, body
mass index, smoking status and prevalent medical conditions. Men aged
40-70
with severe sleep-disordered breathing were twice as likely to die from
any cause as men the same age not suffering from the condition (that is,
those
with AHI less than 5). Death from coronary heart d isease was found to be
associated with sleep-disordered breathing in men, but not in women. Those
who had milder sleep-breathing disorders did not have a statistically
significant increased risk of dying.
As an observational study, this research cannot determine whether
sleep-disordered breathing is the actual cause of deaths, rather than a
factor that
happens to be associated with fatal conditions, nor whether treating
sleep-disorder breathing can lengthen life. To address this question, the
authors
suggest "additional research in the form of randomized clinical trials… to
assess if treatment [of sleep-disordered breathing] can reduce
premature mortality associated with this common and chronic disorder."
Funding:
Supported by the National Heart, Lung, and Blood Institute
through the following cooperative agreements: U01-HL53940 (University of
Washington), U01-HL53941 (Boston University), U01-HL63463 (Case Western
Reserve University), U01-HL53937 (Johns Hopkins University), U01-HL53938
(University of Arizona), U01-HL53916 (University of California, Davis),
U01-HL53934 (University of Minnesota), U01-HL63429 (Missouri Breaks
Research),
and U01-HL53931 (New York University). The funding institutions had no
role in study design, data collection and analysis, decision to publish,
or
preparation of the manuscript.
Competing Interests:
NMP received honoraria and travel support for
continuing medical education lectures or symposia sponsored by Respironics
and
Resmed Inc. DMR is currently the holder (through New York University) of
multiple patents licensed to Covidian and Fisher & Paykel Healthcare on
the
use of nasal CPAP, the primary treatment of obstructive sleep apnea, and
to Advance Brain Monitoring, Protech on diagnostic tools for use in
ambulatory monitoring of sleep apnea, and recieves royalties from these.
DMR has also held industry-sponsored grants relating to sleep and
sleep-disordered breathing treatments with Restore Medical, St. Jude
Medical, Guidant (Boston Scientific), Protech, Advanced Brain Monitoring,
and
Korosensor. At no time were any of the activities of DMR in the Sleep
Heart Health Study data collection or analysis directly related to any of
his
listed activities in ways that compro mised the study, as reviewed
annually by the Steering Committee. SR has National Institutes of Health
grants
that fund research into the association of sleep disorders and health
outcomes. SR is a member of the Sleep Research Society Board of Directors.
SR is
the Principal Investigator for a contract between University Hospitals of
Cleveland and Dymedix, Inc. to validate sleep signals of sleep apnea
diagnosis. MLU has a Baxter Healthcare Grant (Reanalysis of the HEMO Study
using novel analytic approaches). MLU is personally unaware of a Baxter
sleep product and this support did not influence his contribution to this
work.
Citation:
"Sleep-Disordered Breathing and Mortality: A Prospective Cohort Study."
Punjabi NM, Caffo BS, Goodwin JL, Gottlieb DJ, Newman AB, et al. (2009)
PLoS Med 6(8): e1000132. doi:10.1371/journal.pmed.1000132
Source
PLoS Medicine