[Validation of a contact-free sleep apnea monitor in adults with obstructive sleep apnea]

Objective: To evaluate the diagnostic value of a contact-free sleep apnea monitor in Chinese adults with obstructive sleep apnea (OSA). Methods: One hundred and ninety-eight participants with snoring were recruited between July 2018 and May 2019 in Sleep Center of Peking University People's Hospital, using nocturnal polysomnography (PSG) and contact-free sleep apnea monitor simultaneously. We evaluated the difference between respiratory event index (REI) generated by contact-free sleep apnea monitor and PSG-Apnea-Hypopnea Index (AHI). We calculated the sensitivity and specificity of OSA diagnosis using the contact-free sleep apnea monitor by hypothesis testing for means, Pearson correlation coefficient and Bland-Altman plots. Then, we used the receiver operating characteristic (ROC) curve to find out the best cut-off of OSA diagnosis. Results: PSG-AHI and the REI of contact-free sleep apnea monitor showed no statistically significant difference [15.9 (4.7, 40.2) vs. 16.2 (6.1, 40.0), P=0.381], and they were significantly correlated (r=0.914, P<0.05), with mean difference of -0.06 (95%CI:-18.44, 18.31). The ROC curve showed that if REI ≥5 events/h was used as diagnostic criteria, the sensitivity and specificity of diagnosing OSA were 91.2% and 58.0%, respectively. The sensitivity and specificity of the contact-free sleep apnea monitor REI≥13.3 in diagnosing moderate and severe OSA were 90.1% and 71.1%, respectively. Conclusion: The REI obtained from the contact-free sleep apnea monitor showed a good agreement with the PSG-AHI, and therefore, the contact-free sleep apnea monitor can be used for the screening of patients with moderate and severe OSA.