It is still unclear how patients with obstructive sleep apnoea (OSA) should be assessed to determine if they are safe to drive, a European Respiratory Society task force has concluded.
Despite EU legislation setting OSA benchmarks for safe driving, a review of the evidence found that much more research is needed on how to measure vigilance and sleepiness and how that correlates with fitness to drive.
The ERS Statement in the European Respiratory Journal said a standardised model for screening for OSA and identifying those patients at high risk of accidents while driving is needed.
In 2014, the EU introduced a directive requiring that patients with an apnoea or hypopnoea frequency per hour (AHI) of at least 15 AHI >15 and associated sleepiness should not drive until effectively treated and a doctor confirms they are able to continue driving.
Speaking with the limbic, task force member Dr Mark Elliott, said the goal of the ERS taskforce was to look at the evidence on how best to assess a patient’s risk.
“The problem is the ERS Statement raises more questions than answers because of the poor quality or lack of evidence,” he said.
The Task Force found that OSA is a recognised risk factor for driving accidents, but identifying those who are at risk is problematic because there are so many factors to take into account, including whether the patient is taking extra precautions to mitigate their risk.
“Despite the large number of studies, we still lack simple instruments applicable on a large scale that could reliably indicate that a subject with OSA is fit to drive.
“OSA is often unrecognised and screening the population of drivers for the presence of OSA is a difficult task,” the ERS reviewers concluded.
Ultimately it should be the responsibility of the physician to suspect OSA and request diagnostic examination in the case of subjects renewing their driving license, and the primary responsibility for issuing the driving licence remains with the relevant licensing authority, they added.
One aspect the expert group could agree on is that documented use of CPAP for at least 4 hours for at least 70% of nights is considered enough evidence that a patient with OSA is fit to drive.
Some have suggested the use of driving simulators as a way to assess a patient’s risk but they are expensive to use in practice and there is still a lack of data showing that performance on a simulator is predictive of accidents during real driving, the paper concluded.
“The problem is going from the average to the individual,” said Dr Elliott. “In my personal view if you give didactic guidance you end up being being unfair to a large group of people with no evidence.”
In Australia, the medical standards for driver licensing state that a person is unfit to hold a licence if they have have established sleep apnoea syndrome (sleep apnoea on a diagnostic sleep study and moderate to severe excessive daytime sleepiness. The standards recommend that people with sleep apnoea be referred to a specialist sleep physician for further assessment, investigation with overnight polysomnography and management.
According to Austroads: “A person found to be positive for moderate to severe OSA on polysomnography, but who denies symptoms and declines treatment, may be offered a Maintenance of Wakefulness Test (MWT) … For those with a normal MWT, the driver licensing authority may consider a conditional licence without OSA treatment subject to review in one year.”