Lack of night-to-night variability of sleep-disordered breathing measured during home monitoring

The apnea-hypopnea index (AHI) is an important objective measure used in the diagnosis of sleep-disordered breathing. In affected patients, the AHI has been reported to vary across successive nights. We conducted a multichannel home sleep study on 44 patients with sleep-disordered breathing to determine whether the AHI does indeed vary and, if so, to quantify the degree of night-to-night variability. Of this group, 23 patients were tested for 3 consecutive nights and 21 were tested for 2 consecutive nights. Among the group as a whole, we found no statistically significant change in AHI across nights, although we did identify variations among individual patients.