A single polysomnography has been the gold standard for diagnosing obstructive sleep apnoea, but new research suggests the approach may be under or overestimating disease severity for some.
Clinicians’ longstanding reliance on one-night sleep studies to diagnose OSA may finally be due for a rethink, experts say.
Obstructive sleep apnoea – a common chronic sleep disorder characterised by repetitive complete or partial collapse of the upper airway during sleep – affects approximately one billion adults globally.
Early access findings from a Flinders University study, published in npj Digital Medicine, analysed roughly 100 participants’ sleep over three months at home using a Withings Sleep Analyser (WSA) – a flat, under-the-mattress sensor utilising AI to measure the apnoea-hypopnoea index (AHI).
WSA data were subsequently analysed alongside data from participants undergoing a single-night polysomnography (PSG).
When WSA was used as the reference standard, a single-night polysomnography failed to detect OSA in 26% of patients who tested positive on the home monitor. Of the 39 patients who tested positive on the WSA, 10 had previously been classified as not having OSA based on a single-night in-lab or at-home polysomnography.
Conversely, when polysomnography was used as the reference standard, six patients (15%) tested positive on the home WSA device but negative on their sleep study.
Lead author Dr Bastien Lechat from FHMRI Sleep Health said the research identified a fundamental limitation in diagnostic approaches – namely, under or overestimating disease severity in some individuals.
“Our findings show that sleep apnoea can vary considerably from one night to the next, so if you only measure it once, you may not capture the true severity of the condition,” he said.
Professor Sutapa Mukherjee, a senior consultant at Southern Adelaide Local Health Network (SALHN) and Professor of respiratory and sleep medicine, said this variability had important implications for diagnosing and understanding the condition.
“Sleep apnoea is a dynamic disorder, and by capturing how it changes over time, we can build a much more accurate and clinically meaningful picture of a patient’s condition,” she said.
Notably, patients with poor sleep during laboratory testing were more likely to have their OSA severity underestimated.
All patients slept less in the lab than at home, but those misclassified by polysomnography lost approximately 100 minutes more sleep, suggesting that monitoring sleep in the home environment may yield a more accurate diagnosis.
However, researchers concluded the WSA cannot serve as a standalone diagnostic tool since it cannot measure oxygen levels or body position, or distinguish types of apnoeas, limiting its applicability for risk stratification and phenotyping.
Patients with variable OSA severity were more accurately diagnosed with the WSA than with polysomnography, but its accuracy decreased among patients with poor or irregular sleep, such as shift workers. This challenges the ability of simplified devices to estimate OSA severity.
Researchers said future technological advances may help address these limitations.
Beyond high misdiagnosis rates, recent evidence indicates significant night-to-night fluctuations in OSA severity can independently predict adverse health outcomes, such as hypertension and cardiovascular disease, irrespective of a patient’s average OSA severity.
Monash University Associate Professor Brad Edwards, head of the sleep disorders research program, told Allergy & Respiratory Republic that although sleep specialists were aware of AHI’s night-to-night variability, the study more accurately identified sleep apnoea and provided concrete data.
“The waitlist to get these in-lab PSGs can be quite lengthy… sometimes that can take three, six, up to even 12 months,” he said.
More than half (53%) of the study’s participants waited less than three months for an appointment, while almost a quarter (23%) waited more than 12 months.
Professor Edwards said that while WSA “isn’t a complete replacement” for polysomnography, it could help confirm a clinician’s suspected diagnosis, provide quicker results, and initiate treatment sooner, helping to ease the healthcare burden.
Moreover, the more detailed the data a patient has to discuss with a sleep physician, the better the diagnosis and treatment plan, he said.
Often, in-lab sleep studies are reserved for more complex cases than those with a classic presentation, he said – such as overweight, middle-aged men with witnessed apnoeas.
In these more straightforward cases, a WSA could help confirm a diagnosis, he told ARR.
Conversely, he said if patients showed no sleep apnoea over 28 nights of monitoring, this could help direct clinicians to another condition, such as insomnia.
Currently, to Professor Edwards’ knowledge, there is limited data on the causes of OSA variability. The study’s researchers suspected factors such as sleeping position, alcohol and food intake, or airway-related physiological differences, but sample size constraints meant these hypotheses could not be tested.
Meanwhile, there is increasing awareness that sleep apnoea and variability in its severity place patients at greater risk of cardiovascular, metabolic, or neurocognitive problems, Professor Edwards said.
“As the study highlights, there’s roughly one in four people who are likely to be misdiagnosed or missed [with a polysomnography],” Professor Edwards said.
Patients previously undiagnosed with sleep apnoea but with persistent symptoms could consider having another discussion with their sleep physician or GP, he told ARR.
Read the full report here.
