J Rhinol.  2022 Nov;29(3):155-162. 10.18787/jr.2022.00424.

Diagnostic Performance of Photoplethysmography-Based Smartwatch for Obstructive Sleep Apnea

• Kim MW
• Park SH
• Choi MS

• KMID: 2536584
• DOI: http://doi.org/10.18787/jr.2022.00424

Abstract

Background and Objectives
Considering the prevalence and health effects of obstructive sleep apnea (OSA), early diagnosis and proper treatment are essential. Polysomnography (PSG) has limitations in diagnosing or tracking large-scale OSA patients. Smartwatches (SWs) can be equipped with a photoplethysmograph (PPG) that can indirectly measure heart rate and blood oxygen saturation by detecting the difference of light absorption through blood. The purpose of this study is to compare oxygen saturation parameters of PPG-based SWs with those of PSG to determine the diagnostic accuracy for OSA.
Methods
After obtaining voluntary consent from patients who were scheduled to undergo PSG in a sleep clinic due to suspected OSA, they were randomly assigned to wear a Galaxy watch4 (GW) or Apple watch7 (AW) on their wrist. The agreement rates between the oxygen saturation parameters of the two SW types and PSG were evaluated. The accuracy, sensitivity, and specificity of the oxygen saturation parameters for diagnosis of OSA (apnea-hypopnea index [AHI] ≥5/h) were compared between the two types of SW.
Results
A total of 133 patients underwent PSG while wearing an SW. Including duplicates, 109 patients wearing a GW and 69 wearing an AW were included. The diagnostic accuracy of AHI ≥5/h according to oxygen saturation time measured by a GW was less than 90%, the respective sensitivity and specificity were 82.9% and 75.8%. The area under the curve (AUC) of the receiver operating characteristic (ROC) curve was 0.807 (p<0.001). Using the lowest oxygen saturation value of GW, the sensitivity was 81.6%, the specificity was 69.7%, and the AUC of the ROC was 0.849 (p<0.001). The diagnostic accuracy of AHI ≥5/h according to the average oxygen saturation of AW, and the sensitivity and specificity were 75.6% and 70.8%, respectively. The AUC of this ROC curve was 0.757 (p<0.001). Using the lowest oxygen saturation value of AW, the sensitivity was 71.1%, the specificity was 62.5%, and the AUC of the ROC was 0.705 (p=0.005).
Conclusion
This study found that the two types of SW showed considerable accuracy in diagnosing OSA, but the accuracy decreased as the severity of OSA increased.

Keyword

Obstructive sleep apnea; Polysomnography; Photoplethysmography; Wearable electronic devices; Oxygen saturation

Figure

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  Fig. 1. Bland-Altman plots comparing SpO2 parameters between each Smartwatch and PSG. A: GW showed good agreement results when the period of desaturation less than 90% was small, whereas the agreement rate decreased as the difference increased. B: The lowest recorded SpO2 parameter of GW showed a difference of -2.5% on average with the PSG result, and showed a good agreement in all sections. C: The parameter of average SpO2 of AW showed a difference of -1.5% with the PSG result, and showed a good agreement. D: The lowest SpO2 parameter of AW showed a difference of 10% with the PSG result, and showed a fair agreement. GW, Galaxy watch; AW, Apple watch; PSG, polysomnography; SpO2, oxygen saturation.

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  Fig. 2. Receiver-operating characteristic curves of the various oxygen parameters of each Smartwatch in predicting AHI ≥5, AHI ≥15, and AHI ≥30. A: The duration of saturation less than 90% parameter of GW. B: The lowest oxygen saturation parameter of GW. C: The average oxygen saturation parameter of AW. D: The lowest oxygen saturation parameter of AW. GW, Galaxy watch; AW, Apple watch; AHI, apnea-hypopnea index.

Reference

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