Comparison of two home sleep testing devices with different strategies for diagnosis of OSA

Purpose: Home sleep testing devices are being widely used in diagnosis/screening for obstructive sleep apnea (OSA). We examined differences in OSA metrics obtained from two devices with divergent home monitoring strategies, the Apnea Risk Evaluation System (ARES™, multiple signals plus forehead reflectance oximetry) and the Nonin WristOx ₂ ™ (single channel finger transmission pulse oximeter), compared to differences from night-night variability of OSA. Methods: One hundred fifty-two male/26 female subjects (BMI = 30.3 ± 5.6 kg/m ² , age = 52.5 ± 8.9 years) were recruited without regard to OSA symptoms and simultaneously wore both ARES™ and Nonin WristOx ₂ ™ for two nights (n = 351 nights). Automated analysis of the WristOx ₂ yielded oxygen desaturation index (ODI _Ox2 , ≥4% O2 dips/h), and automated analysis with manual editing of ARES™ yielded AHI4 _ARES (apneas + hypopneas with ≥4% O2 dips/h) and RDI _ARES (apneas + hypopneas with ≥4% O2 dips/h or arousal surrogates). Baseline awake oxygen saturation, percent time OpenSPiltSPi 90% O2 saturation (%time OpenSPiltSPi 90%O2Sat), and O2 signal loss were compared between the two methods. Results: Correlation between AHI4 _ARES and ODI _Ox2 was high (ICC = 0.9, 95% CI = 0.87–0.92, p OpenSPiltSPi 0.001, bias ± SD = 0.7 ± 6.1 events/h). Agreement values for OSA diagnosis (77–85%) between devices were similar to those seen from night-to-night variability of OSA using a single device. Awake baseline O2 saturation was significantly higher in the ARES™ (96.2 ± 1.6%) than WristOx ₂ ™ (92.2 ± 2.1%, p OpenSPiltSPi 0.01). There was a significantly lower %time OpenSPiltSPi 90%O2Sat reported by the ARES™ compared to WristOx ₂ (median (IQR) 0.5 (0.0, 2.6) vs. 2.1 (0.3, 9.7), p OpenSPiltSPi 0.001), and the correlation was low (ICC = 0.2). Conclusions: OSA severity metrics predominantly dependent on change in oxygen saturation and metrics used in diagnosis of OSA (AHI4 and ODI) correlated well across devices tested. However, differences in cumulative oxygen desaturation measures (i.e., %time OpenSPiltSPi 90%O2Sat) between the devices suggest that caution is needed when interpreting this metric particularly in populations likely to have significant hypoxia.