Study objectives: We aimed to validate the diagnostic accuracy and night-to-night variability of a simple 3-channel (type IV monitor) portable sleep monitor, ApneaLink (AL), in a population of morbidly obese subjects.
Design: Cross-sectional validation and diagnostic accuracy study.
Setting: Public tertiary care obesity center in Norway.
Participants: A total of 105 (67 females) treatment seeking morbidly obese subjects were included, mean (SD) age 44.3 (11.4) years and BMI 43.6 (5.6) kg/m2.
Interventions: The patients underwent two successive nights of recordings; the first night with the AL only, and the following night with both the reference instrument Embletta (E), a type III portable somnograph, and the AL.
Measurements and results: Main outcomes were diagnostic accuracy of AL as assessed by sensitivity, specificity and area under ROC curves, and level of agreement between AL and E. AL had high diagnostic accuracy at all levels of OSA, and the Bland-Altman plots showed good agreement between AL and E. The sensitivity and specificity of the instrument were 93% and 71% at the AHI cutoff 5 events/h, and 94% and 94% at the AHI cutoff 15, respectively. The night-to-night variability was low.
Conclusion: Our results indicate that a simple 3-channel portable sleep monitor (ApneaLink) has a high diagnostic accuracy in diagnosing OSA in morbidly obese treatment seeking patients. Accordingly, this and similar instruments might help non-specialists to diagnose OSA in morbidly obese patients, and, importantly, help non-specialists to refer patients who need specific treatment to specialist without unnecessary delay.
Keywords: obstructive sleep apnea; portable somnograph; validation.