Many doctors are confused about when it’s safe for their patients with advanced stage disease to get behind the wheel, a new study reports.

In the first survey to investigate the practice of Australian doctors assessing fitness to drive researchers found that palliative care patients are likely to receive inconsistent advice.

According to the investigators, while current guidelines provide advice for driving safety in patients with neurological conditions, they do not provide clear guidance for opioid use and driving safety in patients with advanced disease.

“These are patients who are often on multiple medications, have pre-morbid chronic illness, are undergoing therapeutic regimens and also have progressive disease. All of which contribute to affecting patients overall functional capacity and safety to drive,” the researchers from St Vincent’s Private Hospital in Brisbane noted.

Some 92 palliative medicine specialists completed the online survey presenting various scenarios involving patients with advanced disease that required the doctor to give advice about driving.

But investigators said the results have relevance to all doctors who prescribe opioids, particularly since the survey found “variability in practice and at times substantial discordance with driving guidelines.”

“Deciding when an opioid naïve patient is safe to drive after taking a short acting oral opioid is challenging, hence the variability of responses seen [in the survey].

An opioid naïve person may experience side effects such as sedation, light-headedness and slowed reaction time after taking an opioid … Translating this into apparent effect on driving safety is not simple,” the researchers from St Vincent’s Private Hospital Brisbane said.

While most doctors involved in the study indicated that they would advise a patient to temporarily refrain from driving after taking a short-acting opioid, many were confused about just how long that period should be.

“This is not surprising given the lack of evidence surrounding the effect of acute opioid administration on driving skill,” the investigators said adding that while current evidence is scant it supports the advice that a patient should not drive until 1-2 weeks after starting an opioid.