Screening for subclinical sleep-disordered breathing

Abstract

We evaluated self-administered questionnaires and short sleep studies in screening for sleep-disordered breathing (SDB) in 40 hypertensive men ages 36-66 unselected for symptoms. Each subject completed a questionnaire including questions on sleep-related symptoms and underwent overnight polysomnography in which we evaluated the apnea-hypopnea index (AHI) and the percentage of time during which arterial O2 saturation was <90% (T90). The first 90 min of overnight study was evaluated separately, and 10 subjects with an AHI ≥ 10 also underwent late afternoon nap study. By overnight polysomnography, 48% of the cohort had an AHI ≥ 10, and 35% had a T90 ≥ 10%. Using linear regression, we found no features of the symptom questionnaire that strongly predicted AHI. Only self-reported snoring and baseline arterial PO2 significantly predicted T90. The AHI and T90 were not significantly correlated. Considering an AHI ≥ 10 in the overnight study as ''abnormal'' and an AHI ≥ 10 on the short study as a ''positive'' test, the specificity of the AHI in the first 90 min was 100% (21/21), and the sensitivity was 42% (8/19). The sensitivity of the nap study was 60% (6/10). We conclude that in a cohort unselected for symptoms, the ability of self-administered questionnaires to predict SDB was low; short studies were only moderately sensitive for detecting an AHI ≥ 10, and the AHI was not a major determinant of nocturnal desaturation.