Sleep apnoea: How to assess driving risk

Fiona Clark

writer

Fiona Clark

Journalist

Fiona Clark

Sleep expert Dr Anup Desai runs through assessing the risks and responsibilities.

With rising obesity rates there’s a good chance that around 50 to 60 per cent of your middle-aged and older-aged patients could have Obstructive Sleep Apnoea (OSA). And while we know it is a risk factor for heart disease, stroke and dementia, it also impacts on ability to drive.

The rules on reporting on fitness to drive may vary from state to state but the 2022 Austroads Assessing Fitness to Drive states that a person is not fit to hold an unconditional licence if:

  • “they have an established sleep apnoea syndrome (sleep apnoea on a diagnostic sleep study and moderate to severe excessive daytime sleepiness); or
  • they have frequent self-reported episodes of sleepiness or drowsiness while driving; or
  • they’ve had a motor vehicle crash(es) caused by inattention or sleepiness; or
  • “if the person, in the opinion of the treating doctor, represents a significant driving

risk as a result of a sleep disorder.”

Dr Anup Desai, Sleep Specialist and Medical Director at the Sydney Sleep Centre, says a sleep test is the only validated clinical way of establishing OSA and its severity. This can be used in conjunction with subjective tests like the Epworth Sleepiness Scale (ESS) and the ‘opinion of the treating doctor’ as Austroads states.

 

When does ‘the opinion of the treating doctor’ apply? And what exactly does it mean…

Dr Desai acknowledges that this point is vague and open to interpretation, but says “I believe this would be used when the doctor has a concern regarding the extent of sleepiness or accident risk that the driver reports, relative to the patient’s own report, or in cases of severe OSA where excessive daytime sleepiness (EDS) or accident risk is denied.”

“In these cases, there may be a medical concern of under-reporting or lack of awareness of sleepiness, and for ethical and public safety reasons, the doctor may work on the side of caution by using this criteria as a basis for a conditional licence.”

A conditional licence may involve restricting a patient to day-time driving or necessary driving only, such as to work and home, and is relevant for all ‘at risk’ patients. It can be reviewed after treatment of OSA.

Those at increased risk of OSA tend to be:

  • overweight or obese
  • have comorbidities like hypertension or diabetes
  • post menopause women.

Dr Desai says it’s a good idea to ask these patients about their sleep and day-time drowsiness as you may identify people who have sleep apnoea who could benefit from advice on improving sleep, and sleep apnoea treatments.

“Sleep apnoea is an independent risk factor in various conditions, but it can also be a confounding factor,” he says.

He adds that it’s important to consider and advise on other things that affect sleep quality and duration, such as shift work, certain medications, alcohol consumption, conditions like depression, co-morbid insomnia, and menopause symptoms like night sweats.

Dr Desai says many patients will self-report their sleep issues to GPs, especially if their partner has said they’re snoring, if they’ve had a close shave in the car themselves, or if they feel excessively tired during the day and it’s impacting on their work or quality of life.

There may be people who deny any sleep problems, but “you’re looking at them and you’re thinking, ‘this isn’t adding up,’”. This is when your medical discretion comes into play.

Although he acknowledges it isn’t always easy, Dr Desai says it is the doctor’s responsibility to make patients aware of the risks of driver sleepiness to themselves and others, the possible treatments, and the consequences of not complying with treatment.

“The doctor needs to be open about this and emphasise that it is a requirement of a patient’s licence to understand and manage their medical driving risks. It is the responsibility of the doctor to inform the patient of their licence obligations,” Dr Desai says.

“Driving risks of course also apply in other more easily accepted medical conditions such as seizures or hypoglycaemic episodes, arrhythmias, etc., Dealing with this issue with patients is about broad public safety rather than just the individual’s perspective.”

 

How do you assess the driving risk someone poses?

There are various assessment tools to help determine daytime sleepiness including  the Epworth Sleepiness Scale (ESS). These can be used as subjective measures, but are just one part of a comprehensive assessment and are not sensitive or specific enough to diagnose OSA.

Another useful test to evaluate daytime sleepiness and driving accident risk is the Maintenance of Wakefulness Test (MWT).

Dr Desai says it is useful:

  • in patients with moderate to severe OSA who deny symptoms and decline treatment
  • if there are concerns regarding driving or occupational risk
  • if they’ve already had an accident caused by falling asleep and are seeking to get their licence re-instated.

This test involves the patient staying overnight in a sleep assessment facility and then during the day spending four 40-minute sessions two hours apart in a quiet, dark room to see how well they maintain their alertness. This can give both the patient and doctor a good indication of next steps in treatment. It can also be reassuring and document objectively that driving accident risk has been assessed and controlled.

When it comes to rating the severity of OSA, the overnight sleep assessment is the gold standard as it rates the severity with a Respiratory Disturbance Index (RDI). A score of 5-14.9 is mild, 15-29.9 is moderate and above 30 is severe.

Dr Desai reminds us that GPs must follow up on sleep study results that they directly order and ensure the patient receives appropriate treatment. They should also assess and manage driving risk for the sleep studies they directly order. If a patient has seen a sleep or respiratory physician first for the sleep study, the physician would then usually see the patient to review that result with them and write back to the GP with the management plan.

He says we tend to focus on the patients with moderate to severe sleep apnoea, but we should pay attention to those with mild OSA too.

“Severity of OSA (as defined by the RDI) isn’t necessarily a predictor of a patient’s risk of having a fall asleep motor vehicle accident. Mild, moderate or severe OSA patients can all fall asleep at the wheel and all need to be assessed for driving accident risk as per the Austroads Fitness to Drive Guidelines.”

If a patient refuses treatment or isn’t compliant and the doctor believes they are a risk on the roads, they may have to mandatorily report them to the licencing authorities.

“Patient privacy rules are important, but if we think they are a danger to others on the roads, we have an ethical and medical responsibility to report them; both the AMA and indemnity providers would support that,” Dr Desai explains.

There are risks with that, he warns. “The moment you report the patient they may disappear, and may shun further medical follow up.”

His preferred approach is to establish rapport and trust with the patient and work through a broader treatment approach that includes managing driving risk in the short term and treating their condition over the longer term. Driving restrictions can often be used short term to manage driving risk +/- a maintenance of wakefulness test to objectively assess their alertness and fitness to drive if untreated.

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Fiona Clark

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Fiona Clark

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