Sleep Apnea Increased Mortality in 14-Year Study

BALTIMORE – Moderate to severe sleep apnea significantly increased the risk of all-cause mortality, according to 14 years of follow-up data from a large community sample.

“Sleep apnea is a disease of public health significance,” said Nathaniel Marshall, Ph.D., of the University of Sydney, who presented results from the Busselton Health Study at the annual meeting of the Associated Professional Sleep Societies.

Previous studies have suggested that obstructive sleep apnea (OSA) increases the risk of death from cardiovascular disease, Dr. Marshall said. Until recently, however, the role of sleep apnea as an independent predictor of all-cause mortality has not been well studied, he added.

The Busselton Health Study is an ongoing community-based study in Busselton, Western Australia.

For the study, the researchers analyzed data from 400 community-dwelling adults aged 45-60 years. All of the participants were tested for OSA using a home sleep apnea monitoring device. Sleep apnea was quantified using the respiratory disturbance index (RDI), and moderate to severe apnea was defined as an RDI score of 15 or more respiratory disruptions per hour of sleep.

Complete data were available from 380 participants (278 men and 102 women) after an average of 13.4 years. The mortality rate was significantly higher (33.3%) among the 18 participants who had moderate to severe apnea (six deaths), compared with 6.5% among the 77 participants with mild OSA (five deaths) and 7.7% among the 285 participants without OSA (22 deaths).

Compared with people who did not have sleep apnea, the mortality hazard ratio was 6.24 for people with moderate to severe sleep apnea, after the researchers controlled for risk factors including age, gender, body mass index, mean arterial pressure (as a measure of blood pressure), smoking status, total cholesterol, HDL cholesterol, diabetes status, and physician-diagnosed angina.

“I was suspicious of the size of this effect,” Dr. Marshall said. “If you put this same model into an odds ratio, you get an odds ratio of about 10.” To put it another way, “sleep apnea has about the same effect on mortality as getting 18 years older,” he said.

But the results reflect similar recent findings from two studies in the United States–the multicenter Sleep Heart Health Study and the Wisconsin Sleep Study–that also show significant independent associations between OSA and all-cause mortality.

The association between moderate to severe OSA and all-cause mortality in the Busselton Health Study persisted even in a partly adjusted model that did not control for blood pressure. That model was used for comparison because OSA is a known cause of hypertension, Dr. Marshall noted. However, the researchers found no significant association between mild sleep apnea and an increased risk of death, which is good news, he said.

The study was limited by a lack of information about any treatment of sleep apnea in the study group, but the community-based format of the study kept it free of clinical referral bias, Dr. Marshall explained.

The results suggest that sleep apnea could be added to the list of standard mortality risk factors. But the findings also emphasize the need for randomized controlled trials of sleep apnea treatments that are designed to identify reductions in mortality risk, Dr. Marshall noted.

Dr. Marshall reported that he had no financial conflicts to disclose.

ELSEVIER GLOBAL MEDICAL NEWS

BALTIMORE – Moderate to severe sleep apnea significantly increased the risk of all-cause mortality, according to 14 years of follow-up data from a large community sample.

“Sleep apnea is a disease of public health significance,” said Nathaniel Marshall, Ph.D., of the University of Sydney, who presented results from the Busselton Health Study at the annual meeting of the Associated Professional Sleep Societies.

Previous studies have suggested that obstructive sleep apnea (OSA) increases the risk of death from cardiovascular disease, Dr. Marshall said. Until recently, however, the role of sleep apnea as an independent predictor of all-cause mortality has not been well studied, he added.

The Busselton Health Study is an ongoing community-based study in Busselton, Western Australia.

For the study, the researchers analyzed data from 400 community-dwelling adults aged 45-60 years. All of the participants were tested for OSA using a home sleep apnea monitoring device. Sleep apnea was quantified using the respiratory disturbance index (RDI), and moderate to severe apnea was defined as an RDI score of 15 or more respiratory disruptions per hour of sleep.

Complete data were available from 380 participants (278 men and 102 women) after an average of 13.4 years. The mortality rate was significantly higher (33.3%) among the 18 participants who had moderate to severe apnea (six deaths), compared with 6.5% among the 77 participants with mild OSA (five deaths) and 7.7% among the 285 participants without OSA (22 deaths).

Compared with people who did not have sleep apnea, the mortality hazard ratio was 6.24 for people with moderate to severe sleep apnea, after the researchers controlled for risk factors including age, gender, body mass index, mean arterial pressure (as a measure of blood pressure), smoking status, total cholesterol, HDL cholesterol, diabetes status, and physician-diagnosed angina.

“I was suspicious of the size of this effect,” Dr. Marshall said. “If you put this same model into an odds ratio, you get an odds ratio of about 10.” To put it another way, “sleep apnea has about the same effect on mortality as getting 18 years older,” he said.

But the results reflect similar recent findings from two studies in the United States–the multicenter Sleep Heart Health Study and the Wisconsin Sleep Study–that also show significant independent associations between OSA and all-cause mortality.

The association between moderate to severe OSA and all-cause mortality in the Busselton Health Study persisted even in a partly adjusted model that did not control for blood pressure. That model was used for comparison because OSA is a known cause of hypertension, Dr. Marshall noted. However, the researchers found no significant association between mild sleep apnea and an increased risk of death, which is good news, he said.

The study was limited by a lack of information about any treatment of sleep apnea in the study group, but the community-based format of the study kept it free of clinical referral bias, Dr. Marshall explained.

The results suggest that sleep apnea could be added to the list of standard mortality risk factors. But the findings also emphasize the need for randomized controlled trials of sleep apnea treatments that are designed to identify reductions in mortality risk, Dr. Marshall noted.

Dr. Marshall reported that he had no financial conflicts to disclose.

ELSEVIER GLOBAL MEDICAL NEWS

BALTIMORE – Moderate to severe sleep apnea significantly increased the risk of all-cause mortality, according to 14 years of follow-up data from a large community sample.

“Sleep apnea is a disease of public health significance,” said Nathaniel Marshall, Ph.D., of the University of Sydney, who presented results from the Busselton Health Study at the annual meeting of the Associated Professional Sleep Societies.

Previous studies have suggested that obstructive sleep apnea (OSA) increases the risk of death from cardiovascular disease, Dr. Marshall said. Until recently, however, the role of sleep apnea as an independent predictor of all-cause mortality has not been well studied, he added.

The Busselton Health Study is an ongoing community-based study in Busselton, Western Australia.

For the study, the researchers analyzed data from 400 community-dwelling adults aged 45-60 years. All of the participants were tested for OSA using a home sleep apnea monitoring device. Sleep apnea was quantified using the respiratory disturbance index (RDI), and moderate to severe apnea was defined as an RDI score of 15 or more respiratory disruptions per hour of sleep.

Complete data were available from 380 participants (278 men and 102 women) after an average of 13.4 years. The mortality rate was significantly higher (33.3%) among the 18 participants who had moderate to severe apnea (six deaths), compared with 6.5% among the 77 participants with mild OSA (five deaths) and 7.7% among the 285 participants without OSA (22 deaths).

Compared with people who did not have sleep apnea, the mortality hazard ratio was 6.24 for people with moderate to severe sleep apnea, after the researchers controlled for risk factors including age, gender, body mass index, mean arterial pressure (as a measure of blood pressure), smoking status, total cholesterol, HDL cholesterol, diabetes status, and physician-diagnosed angina.

“I was suspicious of the size of this effect,” Dr. Marshall said. “If you put this same model into an odds ratio, you get an odds ratio of about 10.” To put it another way, “sleep apnea has about the same effect on mortality as getting 18 years older,” he said.

But the results reflect similar recent findings from two studies in the United States–the multicenter Sleep Heart Health Study and the Wisconsin Sleep Study–that also show significant independent associations between OSA and all-cause mortality.

The association between moderate to severe OSA and all-cause mortality in the Busselton Health Study persisted even in a partly adjusted model that did not control for blood pressure. That model was used for comparison because OSA is a known cause of hypertension, Dr. Marshall noted. However, the researchers found no significant association between mild sleep apnea and an increased risk of death, which is good news, he said.

The study was limited by a lack of information about any treatment of sleep apnea in the study group, but the community-based format of the study kept it free of clinical referral bias, Dr. Marshall explained.

The results suggest that sleep apnea could be added to the list of standard mortality risk factors. But the findings also emphasize the need for randomized controlled trials of sleep apnea treatments that are designed to identify reductions in mortality risk, Dr. Marshall noted.

Dr. Marshall reported that he had no financial conflicts to disclose.

ELSEVIER GLOBAL MEDICAL NEWS