Utility of the type 3 portable monitor for the diagnosis of patients with obstructive sleep apnea

Objective To evaluate the utility of a portable monitor at home for diagnosis of obstructive sleep apnea (OSA) in Chinese adults. Methods Eighty nine patients suspected of OSA underwent overnight, unattended home sleep apnea testing (HSAT) with a portable monitor (Nox-T3, Nox Medical Inc. Iceland)followed by an in-laboratory polysomnogram (PSG) with simultaneous portable monitor (PM) recording within one week. PSG and PM recorder were scored according to recommended guidelines by independent technicians. The correlation between PSG apnea hypopnea index (AHI) and PM respiratory disturbance index (RDI) were evaluated. Results Sleep testing showed RDI was (30.0±20.9) events/h on HSAT, and (33.4±22.4) events/h on in-laboratory PM recording. Apnea-hypopnea index (AHI) on PSG was (35.1±23.7) events/h. There was significantly statistical difference among the three group (P<0.001). Both RDI on HSAT and RDI on in-laboratory PM correlated significantly with AHI on PSG (r=0.877, P<0.001 and r=0.962, P<0.001, respectively). Bland-Altman analysis of AHI on PSG versus RDI on HSAT showed a mean difference of 4.4 events/h; limits of agreement was -17.6 to 26.5 events/h. Closer agreements were present when comparing the simultaneous recordings, with AHI on PSG versus RDI on in-laboratory PM showing a mean difference of 1.4 events/h, and limits of agreement was -11.3 to 14.2 events/h. Based on a threshold of AHI≥5 events/h, RDI on HSAT had 98.8% sensitivity, 40.0% specificity. Using an AHI ≥ 15 events/h, RDI on HSAT had 91.5% sensitivity, 76.5% specificity. Conclusion Type 3 PM has a good diagnostic value for adult OSA patients and there is close agreement between the Type 3 portable monitor and PSG. Key words: Sleep apnea, obstructive; Monitoring, ambulatory; Polysomnography; Diagnosis