How common is Sleep Apnea?

The Wisconsin Sleep Cohort Study looked to answer this question. It assessed 602 men and women aged 30-60 years old with an overnight sleep study (polysomnography). These people did not necessarily have symptoms of sleep apnea. It measured how often these people had sleep apnea events and how often people were considered to have symptomatic sleep apnea.

The Wisconsin Study found that:

· 9% of women and 24% of men had an apnea-hypopnea index (AHI) ≥5/hr (at least mild sleep apnea by sleep study), while

· 4% of women and 9.1% of men had an AHI ≥15/hr (at least moderate sleep apnea).

· It was estimated that 2% of women and 4% of men had symptomatic sleep apnea (as defined by being excessively sleepy during the day and having 5 or more sleep apnea events per hour).

The Sleep Heart Health Study is a study designed to look at the relationship of sleep disordered breathing and heart disease. In this study, 886 men and 938 women underwent at-home sleep studies. The number of sleep apnea events was measured using the respiratory disturbance index (RDI) (defined in this study as the number of apneas and hypopneas per hour of sleep).

· 51% had a RDI ≥ 5/hr

· 22% had a RDI ≥ 15/hr

Overall, sleep apnea is a common disorder. More people meet sleep study criteria for a significant number of sleep apnea events than have symptomatic sleep apnea.

REFERENCES:

The occurrence of sleep-disordered breathing among middle-aged adults. Young T, Palta M, Dempsey J, Skatrud J, Weber S, Badr S. N Engl J Med. 1993 Apr 29;328(17):1230-5.

Relation of sleepiness to respiratory disturbance index: the Sleep Heart Health Study. Gottlieb DJ, Whitney CW, Bonekat WH, Iber C, James GD, Lebowitz M, Nieto FJ, Rosenberg CE.

Am J Respir Crit Care Med. 1999 Feb;159(2):502-7.