Increased Mortality in Relation to Insomnia and Obstructive Sleep Apnea in Korean Patients Studied with Nocturnal...

To elucidate the links between the two most prevalent sleep disorders, insomnia and obstructive sleep apnea (OSA), and mortality.

We studied 4,225 subjects who were referred to the Center for Sleep and Chronobiology, Seoul National University Hospital, from January 1994 to December 2008. We divided the subjects into five groups: mild OSA (5 ≤ AHI < 15), moderate OSA (15 ≤ AHI < 30), severe OSA (AHI ≥ 30), insomnia, and a no-sleep-disorder group consisting of subjects without sleep disorders. Standardized mortality ratio (SMR), hazard ratio, and the survival rates of the five groups were calculated and evaluated.

The SMR of all-cause mortality was significantly higher in the severe OSA group than in the general population (1.52, 95% CI 1.23-1.85, p < 0.05). The SMR of cardiovascular mortality increased progressively with the severity of OSA (no-sleep-disorder: 0.09, mild: 0.40, moderate: 0.52, severe: 1.79, p < 0.05). Statistical analyses of the hazard ratios indicated that severe OSA is a risk factor for all-cause mortality (HR 3.50, 95% CI 1.03-11.91, p = 0.045) and cardiovascular mortality (HR 17.16, 95% CI 2.29-128.83, p = 0.006). Cardiovascular mortality was also significantly elevated in the insomnia group (HR 8.11, 95% CI 1.03-63.58, p = 0.046).

Severe OSA was associated with increased all-cause mortality and cardiovascular mortality compared to the no-sleep-disorder group. Insomnia was associated with increased cardiovascular mortality compared to the no-sleep-disorder group.