Nocturnal intermittent hypoxia and metabolic syndrome; the effect of being overweight: the CIRCS study.

AIM

We investigated whether nocturnal intermittent hypoxia, a surrogate marker for obstructive sleep apnea, is associated with metabolic syndrome and its components among Japanese.

METHODS

We examined 1,710 male and 2,896 female community-dwelling Japanese aged 40 to 69, who participated in annual cardiovascular examinations and investigations of sleep. Nocturnal intermittent hypoxia was estimated based on a 3% oxygen desaturation index measured with pulse-oximetry during sleep. No, mild and moderate-to-severe nocturnal intermittent hypoxia were defined by <5, 5 to <15 and >or=15 events/hour, respectively. Metabolic syndrome was defined by modified criteria of the Adult Treatment Panel III guidelines.

RESULTS

Compared with no nocturnal intermittent hypoxia, the multivariable odds ratio of metabolic syndrome was 1.9 (95% confidence interval: 1.6-2.4) for mild and 3.2 (2.2-4.7) for moderate-to-severe nocturnal intermittent hypoxia among men; 2.6 (2.1-3.4) and 5.8 (3.4-9.8) among women, respectively. When stratified by overweight status (body mass index >or=25 kg/m(2)), the multivariable odds ratio of two or more metabolic risk factors (other than overweight) associated with moderate-to-severe nocturnal intermittent hypoxia was 1.9 (1.2-3.1) among non-overweight subjects and 1.4 (0.9-2.1) among overweight subjects (p for interaction=0.002).

CONCLUSIONS

Nocturnal intermittent hypoxia was associated with the accumulation of metabolic risk factors, especially among non-overweight individuals.