Smartwatch-based detection of moderate-to-severe and high-risk obstructive sleep apnea.

PURPOSE: Obstructive sleep apnea (OSA) is a prevalent condition associated with long-term consequences, such as cardiovascular and neurocognitive diseases, yet many cases remain undiagnosed and therefore untreated due to the cost and limited access to traditional in-lab overnight polysomnography (PSG). The ubiquity of consumer wearable technology offers a practical way to mitigate these limitations, enabling more accessible, large-scale screening. However, the clinical validity of these devices requires further testing.

METHODS: In this novel prospective study, we rigorously evaluated the diagnostic performance of the Samsung Galaxy Watch for detecting moderate-to-severe OSA (apnea-hypopnea index, AHI ≥ 15 events/h) compared to in-lab PSG using the AHI, and "high-risk" OSA subjects using the PSG-derived hypoxic burden (HB) criteria. We enrolled 152 adults aged 22 years or older with a prior diagnosis of moderate-to-severe OSA or a high pre-test likelihood of having it (STOP-Bang score ≥ 3), who wore the smartwatch during two in-lab PSG nights (147 completed both nights; total 1,850 h of in-lab PSG sleep): an initial in-lab PSG night, followed by ≥ 3 watch-only at-home nights, and then a second in-lab PSG night. In addition to AHI, we evaluated Galaxy Watch performance across PSG-derived HB-defined risk strata (low- vs. high-risk OSA) as HB integrates the depth, duration, and frequency of oxygen desaturations and has been shown to better reflect cardiometabolic risk and disease severity than AHI.

RESULTS: In our cohort, the Galaxy Watch achieved an area under the receiver operating characteristic (AUROC) curve of 0.94 (95% CI 0.889-0.980) for detecting moderate-to-severe OSA. With the default estimated AHI (eAHI) threshold of 15, the device yielded a sensitivity of 94.1% (95% CI 84.1-98%) and a specificity of 66.7% (95% CI 51-79.4%), while with the cohort-optimized eAHI threshold of 25.95, sensitivity was 82.4% (95% CI 69.7-90.4%) and specificity was 94.9% (95% CI 83.1-98.6%). Notably, within the HB defined high-risk OSA group, the Galaxy Watch achieved 100% sensitivity and 100% specificity using the default threshold, indicating robust discrimination between HB-defined low- and high-risk OSA categories.

CONCLUSION: Overall, these findings highlight the substantial potential of consumer-grade wearables to accurately detect moderate-to-severe sleep apnea using both AHI- and HB-defined risk strata across controlled and real-world settings.

REGISTRATION: ClinicalTrials.gov ID: NCT06603441; First posted: 2024-09-19.

CURRENT KNOWLEDGE/STUDY RATIONALE: Obstructive sleep apnea (OSA) remains substantially underdiagnosed because definitive testing with polysomnography (PSG) is resource-intensive and not readily accessible to all patients. Although consumer smartwatches offer a promising approach for large-scale OSA screening, prospective validation against PSG and evaluation using physiologically meaningful measures such as hypoxic burden have been limited.

STUDY IMPACT: In this prospective study of 152 adults undergoing repeated PSG and smartwatch assessment, the Galaxy Watch demonstrated high accuracy for detecting moderate-to-severe OSA and showed excellent performance for identifying individuals with high hypoxic burden, a subgroup at elevated cardiometabolic risk. These findings support the use of consumer-grade wearable technology as a scalable, accessible screening tool to improve OSA risk identification, triage, and referral for definitive diagnostic evaluation.