Prevalence and comorbidities of SA and based on AI or AHI were captured from 65 studies (11,921 subjects) which spanned the years 1981 to 1997, 36 published after 1990. Thirty-two of these 65 studies were performed in the United States, 21 in Europe, and 12 elsewhere. Average study size was 183 patients (range, 10 to 1,620). Data listings for these studies are provided separately.⁽²⁾ All averages which follow are weighted for sample size. Variability in the reported prevalence of SA, or in the prevalence of associated conditions in SA patients, is likely due to different distributions of age and gender among the populations sampled, and more so due to different criteria for a diagnosis of SA. As with the diagnostic test studies, there appeared to be no consensus in the literature regarding a consistent definition of SA, or common criteria for making the diagnosis. These limitations in the literature should be considered when interpreting the results which follow.

Eleven studies reported the prevalence of SA in general populations of people (total n = 2,410). The mean prevalence of SA in these patients ranged from 0 percent to 33 percent, and averaged 9.2 percent. The prevalence of SA in several special populations were also reported. In 7 studies of healthy elderly (generally over age 60 or over age 70) people (n = 469), the prevalence of SA ranged from 2 percent to 43 percent, and averaged 34.6 percent. In 8 sets of patients with coronary artery disease (total n = 461 patients), the prevalence of SA ranged from 50 percent to 100 percent and averaged 54.9 percent. In 4 studies of hypertensive patients (n = 166 patients), SA was diagnosed in 22 percent to 30 percent, and averaged 26.9 percent. In 3 studies of 1,138 men with erectile dysfunction or impotence, the prevalence of SA ranged from 11 percent to 44 percent and averaged 42.2 percent. (These results are summarized in Evidence Table 14.) For other special populations (stroke, end stage renal disease, congestive heart failure, Alzheimer's disease, depression, and healthy offspring of SA patients), the numbers of studies and patients were very small, and prevalence was not averaged.

Table

Evidence Table 14: Prevalence of sleep apnea.

When reviewing studies of SA patients for the prevalence of associated medical conditions, the most frequently reported condition was hypertension. In 24 studies (n=3,497 patients), the frequency of coincidental hypertension in SA patients ranged from 9 percent to 77 percent and averaged 42.0 percent. In 9 sets of patients with SA, concomitant coronary artery disease was noted in 20.3 percent of patients, on average, and ranged from 2 percent to 33 percent. Ventricular arrhythmias were noted in 5 studies of SA patients (n = 205), ranging from 3 percent to 47 percent of patients monitored, averaging 13.1 percent of patients. There were 5 studies with prolonged follow-up (5 to 13 years) of SA patients, that reported deaths (all causes) in 6 percent to 11 percent of 2,281 SA patients followed, with an average of 7.0 percent (Evidence Table 15).

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Evidence Table 15: Summary of studies with comorbid conditions.