Researchers examined data from 24 previous sleep studies that included a total of 3,250 patients with diagnosed or suspected obstructive sleep apnea. Overall, researchers didn't find a significant difference at a group level in mean Apnea-Hypopnea Index (AHI) between sequential nights in the sleep studies.
However, at the individual patient level, the mean AHI difference between night one and night two of the sleep studies was -1.70/hour.
"Therefore, a single night sleep study might not draw an accurate picture of the disease," said lead study author Dr. Maurice Roeder of the department of pulmonology at University Hospital Zurich in Switzerland.
"The effect of longitudinal sleep monitoring on clinical outcomes like CPAP compliance and excessive daytime sleepiness as well as its cost effectiveness should be subject of future research," Dr. Roeder said by email.
Differences in timing of Rapid Eye Movement (REM) sleep were positively correlated with variation in respiratory events, the researchers report in Thorax.
At the individual level, 41% of the apnea patients in the analysis experienced night-to-night variability in respiratory events of more than 10 per hour.
In addition, 49% of the participants experienced changes in the classification of obstructive sleep apnea severity class at least once in sequential sleep studies, based on thresholds for diagnosing apnea severity at more than 5, 15, or 30 events per hour.
This suggests that about 12% of patients might be missed during a single night at a diagnostic threshold of more than 5 or 15 respiratory events an hour, the study team notes. And, about 10% of patients would be missed during a single night at a diagnostic threshold of more than 30 events per hour.
One limitation of the analysis is that most of the smaller studies were non-interventional observational studies, not randomized trials, the study team notes. The smaller sleep studies also used a variety of protocols, devices, scoring rules, and sleep environments to assess respiratory events.
It's also possible that the inclusion criteria, which required the time between two sleep studies to be less than six months, may have been too broad, said Dr. Vishesh Kapur of the division of pulmonary, critical care, and sleep medicine at the University of Washington in Seattle.
"Six months is a relatively long time during which a patient's sleep apnea could change due to weight change, nasal congestion or other factors," Dr. Kapur, who wasn't involved in the study, said by email.
Nonetheless, the results underscore that clinicians may not be able to accurately diagnose obstructive sleep apnea from a single night of observation, Dr. Kapur said.
"If you have a symptomatic patient with symptoms that make you suspect obstructive sleep apnea that has a negative polysomnogram consider repeating the study since you may document sufficient sleep apnea to offer therapy that could benefit the patient," Dr. Kapur recommended.
By Lisa Rapaport
SOURCE: https://bit.ly/33PVQlh Thorax, online August 13, 2020.
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