In a report published in the August 1, 2008 edition of Sleep, Australian researchers have reported findings that indicate that the interrupted nighttime breathing of sleep apnea appears to increase the risk of death.
While earlier studies have made this link, they were conducted in sleep centers, and not in the general community. The new study suggests a much broader risk among all people with obstructive sleep apnea. In fact, in a news release, researcher Nathaniel Marshall, a postdoctoral fellow at the Woolcock Institute of Medical Research in Sydney, stated that "This is the first study to demonstrate an independent association between all-cause mortality and sleep apnea in a community-based study."
"The size of the increased mortality risk was surprisingly large," Marshall continued. "In our particular study, a sixfold increase means that having significant sleep apnea at age 40 gives you about the same mortality risk as somebody aged 57 who doesn't have sleep apnea."
Sleep apnea is a sleep disorder characterized by repeated pauses in breathing during sleep, each pause lasting long enough so that one or more breaths is missed.
The current study included 380 participants, consisting of men and women 40 to 65 years old. Among them, three had severe obstructive sleep apnea, 18 had moderate sleep apnea, and 77 had mild sleep apnea. The remaining 285 people did not suffer from sleep apnea.
During 14 years of follow-up, participants who died consisted of about 33% of those with moderate to severe sleep apnea, 6.5% of those with mild sleep apnea, and 7.7 percent of those without the condition. The researchers noted that the deaths of patients with mild sleep apnea could not be directly tied to the condition. As to the 33% death rate of those with the moderate to severe condition, Marshall stated that "Our findings ... remove any reasonable doubt that sleep apnea is a fatal disease,"
Commenting on these findings, Dr. David M. Claman, director of the Sleep Disorders Center at the University of California, San Francisco, stated that "This Australian data has additional strengths in that it is a population-based prospective sample with a long period of follow-up," adding that he believes the study to have strengthened the conclusion that severe obstructive sleep apnea contributes to cardiovascular illness and death.
More reinforcement for these conclusions comes from a University of Wisconsin study , where researchers found severe sleep apnea was associated with a threefold increased risk of dying. They further concluded that for those with moderate to mild sleep apnea, the risk of death was increased 50% over people without sleep apnea.
In yet another study on the effects of sleep apnea, Japanese researchers reported in the June issue of the journal Urology, that nocturia, frequent urination during the night, appears to be a fairly common condition among men suffering from obstructive sleep apnea,
In the study, Dr. Yoji Moriyama of Gifu University School of Medicine and colleagues studied the occurrence of nocturia (defined as needing to void two or more times each night), and other urinary symptoms, classifying their subjects according to the frequency of night-time urination and age (younger than 50, and older than 50).
The findings showed nocturia to be present in 41% of their subjects, and that the risk of nocturia was directly related to the severity of sleep apnea, and that the association was particularly strong in patients under 50 years of age.
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