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Effects of Varying Approaches for Identifying Respiratory Disturbances on Sleep Apnea
Assessment.
ABSTRACT Varying approaches to measuring the respiratory disturbance index (RDI) may lead to discrepant
estimates of the severity of sleep-disordered breathing (SDB). In this study, we assessed the impact of varying the
use of corroborative data (presence and degree of desaturation and/or arousal) to identify hypopneas and apneas. The
relationships among 10 RDIs defined by various definitions of apneas and hypopneas were assessed in 5,046 participants
in the Sleep Heart Health Study (SHHS) who underwent overnight unattended 12-channel polysomnography (PSG). The magnitude
of the median RDI varied 10-fold (i.e., 29.3 when the RDI was based on events identified on the basis of flow or volume
amplitude criteria alone to 2.0 for an RDI that required an associated 5% desaturation with events). The correlation
between RDIs based on different definitions ranged from 0.99 to 0.68. The highest correlations were among RDIs that
required apneas and hypopneas to be associated with some level of desaturation. Lower correlations were observed between
RDIs that required desaturation as compared with RDIs defined on the basis of amplitude criteria alone or associated
arousal. These data suggest that different approaches for measuring the RDI may contribute to substantial variability in
identification and classification of the disorder.
