Rationale: The most common single channel devices used for obstructive sleep apnea (OSA) screening are nasal airflow and oximetry. No studies have directly compared their role in diagnosing OSA at home.
Study objectives: To prospectively compare the diagnostic utility of home-based nasal airflow and oximetry to attended polysomnography (PSG) and to assess the diagnostic value of adding oximetry to nasal airflow for OSA.
Design: Cross-sectional study.
Setting: Laboratory and home.
Participants: Sleep clinic patients with suspected OSA.
Interventions: All patients had laboratory PSG and 2 sets of 3 consecutive nights on each device; nasal airflow (Flow Wizard, DiagnoselT, Australia) and oximetry (Radical Set, Masimo, USA) at home in random order.
Results: Ninety-eight of the 105 patients enrolled completed home monitoring. The accuracy of nasal airflow respiratory disturbance index (NF RDI) was not different from oximetry (ODI 3%) for diagnosing OSA (area under the ROC curve (AUC) difference, 0.04; 95% CI of difference -0.05 to 0.12; P = 0.43) over 3 nights of at-home recording. The accuracy of NF RDI was higher after 3 nights compared to one night (AUC difference, 0.05; 95% CI of difference, 0.01 to 0.08; P = 0.04). Addition of oximetry to nasal airflow did not increase the accuracy for predicting OSA compared to nasal airflow alone (P > 0.1).
Conclusions: Nasal flow and oximetry have equivalent accuracy for diagnosing OSA in the home setting. Choice of device for home screening of sleep apnea may depend on logistical and service delivery issues.