Nightly variability of sleep-disordered breathing measured over 3 nights.

Abstract

To examine the nightly variability of sleep-disordered breathing (SDB) as measured by the apnea-hypopnea index (AHI). Retrospective comparison of 3 sequential nights of testing performed in the home in 1091 patients who were referred for diagnostic testing of SDB. The Pearson and Intraclass correlation coefficients ranged between 0.88 and 0.90 for each pair of nights. Based on night 1, approximately 90% of patients were classified consistently with "AHI-high" (the highest AHI measured across the 3 nights) using an AHI threshold of 5. However, 10% were misclassified on night 1 relative to the highest AHI level. These findings suggest that (1) 1 night of diagnostic testing for SDB is not sufficient to diagnosis SDB in approximately 1 of every 10 cases, and (2) there is little, if any, significant nightly change in SDB in the home environment. D.