Conducting only a single night of portable monitoring can misclassify disease severity in patients with mild to moderate sleep apnea, according to study results published in CHEST.
The study enrolled 10,340 adults with sleep apnea who were referred to a diagnostic testing facility for a sleep study. An at-home sleep apnea test was performed by a self-applied type 3 monitor, which was used for 3 consecutive nights. The monitor assessed oxyhemoglobin saturation, oro-nasal airflow, and chest excursion.
Researchers determined the apnea-hypopnea index (AHI) for each night and computed a reference AHI using data from all 3 nights. In addition, the researchers identified the presence and severity of sleep apnea based on 4 thresholds of individual AHI and the reference AHI values: <5.0 (normal), 5.0 to 14.9 (mild), 15.0 to 29.9 (moderate), and ≥30.0 (severe).
There were strong and consistent associations between the AHI values between night 1 and night 2 (r=0.89; 95% CI, 0.88-0.90), night 1 and night 3 (r=0.87; 95% CI, 0.86-0.88), and night 2 and night 3 (r=0.89; 95% CI, 0.88-0.90). Substantial within-patient variability was observed in the AHI values (average standard deviation, 4.4 events/h). In addition, the researchers observed that approximately 40% of patients who were underdiagnosed on the first night relative to the reference AHI remained underdiagnosed after additional nights of testing.
Any 1 night of monitoring resulted in substantial misclassification of disease severity. When compared with the reference AHI value derived from all 3 nights, approximately 93% of patients with a normal study on night 1 and 87% of patients with severe sleep-disordered breathing on night 1 were correctly classified. Conversely, 20% of patients with mild and moderate sleep-disordered breathing on night 1 were misdiagnosed as either not having sleep apnea or having mild sleep apnea.
Study limitations included the lack of data on alcohol intake and the use of sedative medication, which the investigators suggested could have contributed to variability in AHI between each night.
The researchers concluded that portable monitoring across multiple nights “clearly provides an alternative for more diagnosing sleep apnea that is accessible for all health care professionals.”
Punjabi NM, Patil S, Crainiceanu C, Aurora RN. Variability and misclassification of sleep apnea severity based on multi-night testing [published online February 17, 2020]. CHEST. doi:10.1016/j.chest.2020.01.039