The Accuracy of Repeated Sleep Studies in OSA: A Longitudinal Observational Study With 14 Nights of Oxygen Saturation Monitoring

Background Strong evidence exists for clinically relevant night-to-night variability of respiratory events in patients with suspected OSA. Research Question How many sleep study nights are required to diagnose OSA accurately? Study Design and Methods Patients with suspected OSA underwent up to 14 nights of pulse oximetry (PO) at home and one night of in-hospital respiratory polygraphy (RP). The accuracy of each of the 13 sleep study nights was analyzed using the mean oxygen desaturation index 3% (ODI 3%) of all 14 nights as a reference. Multiple regression analyses assessed possible predictors for night-to-night variability. Results One hundred three patients underwent in-hospital RP. Using only the results of the RP, 19.7% were misdiagnosed using an ODI 3% cutoff of 15/h. One hundred eight patients underwent properly performed PO studies at home with a coefficient of variation (CV) of 31.5% (SD, 14.7%) across all nights. The first PO night demonstrated a sensitivity of 71.4% (95% CI, 55.4%-84.3%) and a specificity of 89.4% (95% CI, 79.4%-95.6%) to diagnose moderate OSA. Using only the first PO night, the negative predictive value was 83.1%. Adding a second recording night increased sensitivity up to 88.1% (95% CI, 74.4%-96.0%) with a slightly lower specificity of 85.9% (95% CI, 74.9%-93.4%). The ODI 3% of the in-hospital RP showed an independent negative association to the log-transformed CV (exponentiated coefficient, 0.989; 95% CI, 0.984-0.995). Interpretation One single night of in-hospital RP may miss relevant OSA. Multiple study nights, for example, using ambulatory oxygen saturation monitoring, increase accuracy for diagnosing moderate OSA