Diagnostic test evaluation of a nasal flow monitor for obstructive sleep apnea detection in sleep apnea research

In this diagnostic test evaluation of a nasal flow monitoring device for obstructive sleep apnea (OSA), 34 patients referred for polysomnography were studied at home for three consecutive nights with the monitor. The mean age of subjects (+/- SD) was 41.9 +/- 10.3 years, and their mean apnea-hypopnea index (AHI) was 31.5 +/- 27.2. The difference between the average AHI from three nights at home on the monitor and the polysomnogram (PSG) result was 1.8 +/- 17.1. The area under the receiver operating characteristic curve (AUC) for PSG AM >= 10 was .96. With a threshold AHI of 18 on the flow monitor, sensitivity was .92, specificity .86, positive predictive value .96, and negative predictive value .75. For detecting severe OSA (AHI >= 30), the AUC was .85. With knowledge of appropriate thresholds and the pretest risk of OSA, the flow monitor can be used to detect or exclude OSA for sleep-related research, as well as to identify severe cases needing priority for further evaluation.