A Comparison of a Wrist-Worn Portable Device (WatchPAT 200)™ with In-Lab Polysomnography for the Diagnosis of Obstructive Sleep Apnea

To assess the sensitivity of WatchPAT 200 for the diagnosis of moderate-to-severe OSA and diagnosis of OSA (any severity) using in-lab full-night polysomnography (PSG) as the gold standard in Indian subjects. The concordance rate between the two devices for the severity category of OSA was also assessed.

This was a retrospective study involving patients who underwent simultaneous sleep study using WatchPAT 200 and in-lab polysomnography for the diagnosis of OSA during the study period. A baseline evaluation using the Epworth sleepiness scale, STOP-BANG questionnaire, and co-morbidities assessment was done for all patients. Pearson’s correlation coefficients and Bland–Altman plots were used to assess the correlation and agreement.

Among 70 subjects, 91.4% were diagnosed as OSA with PSG. The sensitivity of WatchPAT 200 for the diagnosis of moderate-severe OSA was 98.15% while for OSA (any severity) was 100%. The overall concordance or accuracy rate—i.e., the same diagnoses by both diagnostic modalities—was 75.71%. The median (IQR) of pAHI and nadir SpO2 were 42 (18.95–64.35) events/h and 78 (68.75–85.25), respectively. A high correlation (r = 0.87, p < 0.001) and good agreement were found between pAHI and AHI. The mean pAHI-AHI was 7.8 (95% confidence interval [CI], 4.55–11.01) with watchPAT overestimating AHI in most cases.

WatchPAT 200 has a good sensitivity and negative predictive value for the diagnosis of OSA; however, it tends to overestimate AHI and leads to diagnostic severity misclassification in one-fourth of subjects.