MORE than half of patients with “clinically relevant” obstructive sleep apnoea (OSA) may miss out on further assessment under new Medicare criteria enabling GPs to directly refer patients for sleep studies, say researchers in this week’s MJA.
The researchers found that the combination of apnoea screening questionnaires – the Berlin (BQ), STOP-Bang and OSA-50 – with the Epworth sleepiness scale (ESS) was useful for identifying patients requiring further investigation for OSA, but missed more than half of those with “clinically relevant OSA”.
In November 2018, new Medicare criteria were introduced allowing GPs to directly refer eligible patients for sleep studies, if they had positive BQ results in at least two categories, an OSA-50 score of 5 or more, or a STOP-Bang score of at least 4, together with an ESS score of 8 or more.
The MJA authors evaluated 424 patients enrolled in the Tasmanian Longitudinal Health Study. They found that combining the screening questionnaires with the ESS resulted in high specificity (94–96%), but sensitivity was low at 36–51%.
Clinically relevant OSA was defined as moderate to severe OSA (15 or more oxygen desaturation events per hour) or mild OSA (5–14 desaturation events per hour) plus excessive daytime sleepiness.
The researchers said more work was needed to better identify patients with clinically relevant OSA who could benefit from treatment, and a STOP-Bang/ESS-based decision support tool, described in their article, may help GPs in identifying patients for assessment and referral.
But one expert said the researchers’ definition of “clinically relevant OSA” was casting the net too wide, contributing to their conclusion that approximately 50% of patients would be missed using the recently introduced MBS OSA screening guidelines.
Professor Doug McEvoy, a Practitioner Fellow of the National Health and Medical Research Council at the Adelaide Institute for Sleep Health at Flinders University, said there was a lot of debate about the patients with sleep apnoea who benefited from treatment.
“The evidence is very strong that people who are sleepy, and have associated quality of life or mood disturbance, benefit from continuous positive airway pressure (CPAP) therapy,” he said.
Also, patients with resistant hypertension have been shown to benefit from treatment, Professor McEvoy said.
But, he said, despite clinical guidelines recommending treatment to lower cardiovascular and metabolic risk in non-sleepy patients with more than 15 obstructive breathing events per hour, the evidence did not support this.
“If [people] are not sleepy, recent randomised controlled trials have cast considerable doubt on the commonly held belief they will benefit from CPAP [continuous positive airway pressure] treatment,” said Professor McEvoy, pointing to two recent articles he authored in European respiratory journals (here, and here).
Professor McEvoy was supportive of the current Medicare criteria.
“The new Medicare requirement says patients suspected of having OSA need to have at least moderate to severe sleepiness to warrant an investigation in the first place, and I would agree with that. I think that is where the benefit lies for treatment,” Professor McEvoy said.
However, Professor David Hillman, Clinical Professor at the University of Western Australia’s Centre for Sleep Science, said the Medicare referral criteria were not satisfactory at present and required further thought.
“They risk compounding underdiagnosis of an already significantly underdiagnosed problem. However, if the astute GP remains concerned about the possibility of OSA despite the patient not reaching these thresholds for direct referral for sleep study, she or he can still refer the patient for a sleep specialist opinion,” Professor Hillman told InSight+.
He said questionnaire-based tools were inherently limited, although there may be “marginal benefit” in further tweaking them.
“Patients with highly suggestive, problematic symptoms need a diagnostic test – in this case, a sleep study – and simple, low-cost options should be available in this regard,” said Professor Hillman, who says funding level low-cost level 3 and 4 sleep studies would help.
Professor Danny Eckert, Director of the Adelaide Institute for Sleep Health, said the MJA findings highlighted the need to be cautious of negative screening results, particularly when common symptoms or comorbid disease were present.
“While the current study confirms that a positive screening result with the newly implemented tools for GPs to recommend people for sleep studies for people with suspected OSA performs quite well, the ability to rule out clinically significant OSA with a negative screening result using recommended cut-offs is inadequate,” he said.
“This is a problem, as untreated OSA can have a deleterious effect on health, wellbeing, productivity and safety not only for the individual but, as highlighted in the recent Parliamentary Inquiry into sleep health awareness, society more broadly.”
Professor Eckert said missing clinically important OSA in people with comorbid disease may be especially concerning because OSA may be an important treatable modifier of not only the consequences of OSA but potentially for the comorbid disease as well.
Professor Eckert said the MJA authors’ decision support tool could help to improve diagnostic accuracy.
“While this proposed approach requires further investigation and validation, it has considerable potential and should be pursued,” he said.
Professor Eckert said GPs could also tap into resources prepared by the Australasian Sleep Association.