SAN ANTONIO – , results from a large longitudinal analysis showed.
“The association between severe OSA and significant morbidity and mortality – particularly cardiovascular in nature – is well established,” the study’s first author, Alexandros N. Vgontzas, MD, said at the annual meeting of the Associated Professional Sleep Societies. “In contrast, mild to moderate OSA is highly prevalent in the general population but its association with morbidity and mortality is not well established.”
In an effort to examine the association between mild to moderate OSA and all-cause mortality, Dr. Vgontzas and colleagues drew from the Penn State Adult Cohort, a random general population sample of 1,741 men and women who were studied in the sleep lab with an 8-hour polysomnography at baseline and followed for a mean of 19.2 years for all-cause mortality.
The researchers retrieved mortality data from the Centers for Disease Control and Prevention’s National Death Index and defined mild OSA as an apnea/hypopnea index (AHI) of 5-14.9 events per hour, while moderate OSA was defined as an AHI of 15-29.9 events per hour. They used Cox proportional hazards regression to estimate all-cause mortality and adjusted for race, sex, body mass index, smoking, hypertension, diabetes, heart problems, and stroke.
Dr. Vgontzas, of the Sleep Research and Treatment Center at Penn State University, Hershey, Pa., reported that 596 individuals have died since the study began. On adjusted analysis, patients with an AHI between 5 and 29 were 1.28 times as likely to die overall (P = .019). The researchers found that the association with mortality was stronger among patients younger than age 60, compared with those aged 60 and older. The hazard ratio was 1.44 for study participants younger than age 60 (P = .027), and 1.14 for those aged 60 and older (P = .34).
“Mild to moderate sleep apnea is associated with significant all-cause mortality risk, but the strength of the association decreases markedly with age,” Dr. Vgontzas concluded. “These findings are in line with previous findings that the association of mild to moderate OSA with cardiometabolic risk is modified by age and suggests that OSA in older adults is a distinctly different phenotype than in the young and middle-aged.”
The explanation for the association remains unclear. “Is it because the people of older age have some kind of genetic protection, or is because their sleep apnea is milder?” he asked. “We don’t have the data to tell.”
Dr. Vgontzas reported having no financial disclosures.
SOURCE: Vgontzas A et al. .