Performance of the Fitbit Charge 2 and Galaxy Watch 2 compared with polysomnography in assessing patients with obstructive sleep apnoea

Wearable devices may be used to evaluate sleep in patients with obstructive sleep apnoea (OSA). This study compared the use of two wearable devices (the Fitbit Charge 2 (FC2) and Galaxy Watch 2 (GW2)) with that of polysomnography (PSG) for assessing the sleep time of OSA patients. A total of 127 consecutive patients with OSA underwent overnight PSG while wearing the FC2 and GW2 on their nondominant wrist. We compared the total sleep time (TST) determined by the devices with that obtained by PSG with paired t tests, Bland‒Altman plots, and interclass correlations. Moreover, we evaluated the time in each sleep stage and differences due to OSA severity. The mean age of the OSA patients was 50 years, and the mean apnoea-hypopnea index was 38.3 events/h. The recording failure rate was not significantly different between the GW2 and FC2 (15.7% vs. 8.7%, p = 0.106). Compared to PSG, both the FC2 and GW2 underestimated TST by 27.5 and 24.9 minutes, respectively. TST bias in both devices did not correlate with OSA severity. The FC2 and GW2 underestimated TST, which should be considered when monitoring sleep time in patients with OSA.