Purpose: The aim of the current pilot study is to compare the diagnostic accuracy of the NOX T3(TM) (T3) portable sleep monitor (PM) to that of simultaneously recorded in-lab polysomnogram (PSG).
Methods: A total of 40 participants were recruited following face-to-face evaluation at a sleep disorders clinic. Each participant wore both PSG and PM equipment simultaneously during their in-lab PSG. PSG records were manually scored using the American Academy of Sleep Medicine (AASM) criteria, and PM records were double-scored using the device's autoscore algorithm as well as manual scoring.
Results: The final sample consisted of 32 participants (56% male, 50% black) with a mean ESS, BMI, and apnea-hypopnea index (AHI) of 10.4, 32.8, and 16.3, respectively. Three participants (7.5%) were excluded for poor PM signal quality. Mean AHI derived from the T3's autoscore algorithm was similar to that from manual scoring (19.6 ± 18.9 vs. 18.6 ± 19.1, respectively). Autoscore-derived T3 AHI and PSG-derived AHI were strongly related (r = .93). The T3 (autoscored AHI) demonstrated a high degree of sensitivity for the presence of obstructive sleep apnea syndrome (OSA; 100%) and acceptable specificity for the exclusion of OSA using an AHI cutoff of ≥5 events/h (70%). The unit (autoscored) had a high degree of both sensitivity (92%) and specificity (85%) when the presence of OSA was defined more conservatively (AHI > 15 events/h). For OSA defined as an AHI of ≥5, the T3 (autoscored) correctly identified 88% of positive cases and 100% of negative cases.
Conclusions: In this small, clinic-based sample, the T3 demonstrated very good measurement agreement compared to PSG and a high degree of sensitivity for detecting even mild OSA. False positives appeared to be due to respiratory effort-related arousals (RERAs) being autoscored as obstructive apneas and may be due to inherent discrepancy in flow measurement sensitivity between PSG and portable monitors.