• Helen S Driver, Effie J Pereira, Kathryn Bjerring, Fern Toop, Steven C Stewart, Peter W Munt, and Michael F Fitzpatrick.
• Sleep Disorders Laboratory, Kingston General Hospital and Queen's University, Department of Medicine, Ontario. driverh@kgh.kari.net
• Can. Respir. J. 2011 May 1; 18 (3): 137-43.

BackgroundPortable monitors are increasingly being used as a diagnostic screening tool for obstructive sleep apnea (OSA), and in-laboratory validation of these devices with polysomnography (PSG) is required.ObjectiveTo assess the reliability of the MediByte (Braebon Medical Corporation, Canada) type 3 screening device compared with overnight PSG.MethodsTo cover a range of OSA severity, a consecutive series of patients wore the screening device while simultaneously undergoing PSG. Data acquired from the screener and PSG were blinded and scored separately. The number of apneas and hypopneas per hour were calculated using recording time (respiratory disturbance index [RDI]) for the MediByte device, and sleep time (apnea-hypopnea index [AHI]) for PSG.ResultsData from 73 patients with a mean age of 53 years and body mass index of 32.2 kg⁄m2 showed high measurement association between the RDI and AHI, with a Pearson correlation of 0.92, accounting for 85% of the variance. Based on Bland-Altman measurement agreement, the mean difference between the RDI and AHI (-5.9±11.2 events⁄h) indicated screener under-reporting. For an AHI of greater than 15 events⁄h, the sensitivity and specificity of the screener was 80% and 97%, respectively; for an AHI of greater than 30 events⁄h, the positive predictive value was 100%, while the negative predictive value was 88%.ConclusionThe MediByte device accurately identified patients without OSA and had a high sensitivity for moderate-to-severe OSA.

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