Ignorance reigns when it comes to medicinal cannabis

6 minute read

Fresh research shows urgent need for improved training to overcome the GPs' knowledge gap over medicinal cannabis

A landmark survey of Australian general practitioner attitudes and knowledge about medicinal cannabis has returned a result most would freely admit: ignorance reigns.

Most polled GPs lacked sufficient knowledge to talk about medicinal cannabis with patients, they said, and couldn’t discuss available medicines or how to access them, nor their potential harms.

Just over half of 640 GPs surveyed by University of Sydney researchers late last year nonetheless supported medicinal cannabis on prescription. While that made the cohort more conservative than the general Australian population – which has expressed roughly 85% support – an additional 30% of respondents were neutral on the subject.

The survey results were published overnight in the BMJ.

GPs self-reported “very low” knowledge of the effects, products and process of accessing medicinal cannabis. Just one in 10 understood the current regulatory environment, two-thirds had no idea how to get access for their patients, while four out of five said they did not have good knowledge of its effects.

Only 28.8% felt comfortable discussing medicinal cannabis with patients.

While just 22.8% of respondents felt there was scientific evidence to support the efficacy of medicinal cannabis, half were neutral.

Support was more likely for treatment of chronic cancer pain (80.2% of all respondents) and intractable epilepsy (70.3%) – indications that had a higher evidence base and were also more likely to be supported by state governments, the researchers said.

Concerns centred on abuse and dependence (27.7% would not prescribe medicinal cannabis for this reason), while some GPs worried about repeating historical mistakes made with opioids and benzodiazepines.

But more than half of GPs with an opinion on whether medicinal cannabis was less hazardous than other prescription medicines thought it was safer than statins and antidepressants, 78.1% thought it was safer than chemotherapy drugs, and about three in four GPs thought it safer than opioids and benzodiazepines.

High-profile cannabis researcher and medicinal chemist Professor Iain McGregor, of the University of Sydney’s Lambert Initiative for Cannabinoid Therapeutics, led the study.

Professor McGregor, who has published more than 50 papers on cannabinoids in the past two decades, told The Medical Republic his team was “surprised and delighted” by the mix of positive and neutral sentiment, which he called “sensible”.

“Everyone acknowledges that the evidence [for medicinal cannabis efficacy] is far from perfect – the historical prohibitions around cannabis have been a major impediment to research. But it’s possible to draw reasonable conclusions with a high degree of confidence in some cases about the effects of medicinal cannabis on certain conditions,” he told TMR.

“You shouldn’t drive when you’re high on a THC preparation and cannabis dependence does exist… but adverse effects are far below those of benzodiazepines and opioids and many other drugs that are just routinely prescribed in clinical practice.”

The professor estimated around 100,000 Australians use illicit cannabis for medicinal purposes, based on the number of registered patients in Canada. Only around 700 Australian patients had been prescribed the substance since it was legalised in late 2016, with the majority of prescriptions coming from specialists.

Just over 60% of respondents reported at least one patient enquiry about medicinal cannabis in the three months prior to completing the survey, with some receiving more than five enquiries.

That may not sound particularly onerous, given Australians make roughly 6000 visits per full-time equivalent GP each year. But Professor McGregor said anecdotal evidence suggested an escalation of enquiries had followed this “snapshot” from last year after more recent “media hype”.

The researchers wrote that “ongoing media coverage” was “fuelling unrealistic patient expectations regarding therapeutic efficacy and cannabis access”, potentially forcing GPs into a gatekeeper role despite their limited knowledge, training and prescribing capacity.

“This is the terrible dilemma of GPs – that in a way they’re on the frontline dealing with patients’ expectations, but the current system hasn’t really empowered them,” Professor McGregor said.

“They have to deal with patients coming along with [chronic pain unresponsive to] every opioid and gabapentinoid known to mankind, saying ‘none of them have really worked, can I give cannabis a go?’”

The researchers concluded there was an “urgent need” for improved training to overcome the knowledge gap, and also called for more prescribing powers for GPs.

Lambert Initiative researchers surveyed GPs at one-day seminars in Sydney, Melbourne, Brisbane, Adelaide, and Perth run by GP education company HealthEd between August and September of last year.

Each seminar covered multiple medical topics, and while Professor McGregor spoke on medicinal cannabis at each, the surveys were distributed and collected before he presented.

Respondents skewed female (n=428 or 67.3%, compared with 44.7% of the Australian GP cohort). The researchers defended the low response rate of 37% by saying it exceeded typical GP survey response rates.

Professor McGregor told TMR he had not received funding any from medicinal cannabis drug companies. “They’ve run clinical trials with various products from various companies, but it’s all been at arms’ length.”

He said he didn’t own shares or have any commercial interest in the companies involved.

While his organisation was increasingly involved in advocacy and policy work, its “core activity” was developing novel cannabinoid therapeutics, Professor McGregor said.

The Lambert Initiative was established in 2015 by a mammoth $34 million donation from millionaire businessman Barry Lambert.

Despite poor knowledge and reservations about efficacy, almost 80% of respondents backed a GP-led access model, while three in five supported a model that shared care with specialists, and 44.6% supported specialist-only prescribing.

A question added later in the survey (n=398) which asked GPs to select their preferred model saw 41.2% choose trained GP-only, 29.6% “shared care” and 14.6% specialist-only prescribing.

Professor McGregor guessed this was because specialists, led by the Australian College of Physicians, have been relatively conservative on the issue of medicinal cannabis. He also pointed to cost and access issues around specialists, and suggested professional resentment might play a role.

“I think there’s a certain level of resentment there that [GPs] are entrusted with potentially far more hazardous or lethal drugs yet they’re not entrusted with medicinal cannabis,” Professor McGregor said.”That somehow you need to be a specialist in order to handle that one, even though nobody ever died of a cannabis overdose, and 50,000 people died in the US of opioid overdoses last year.”

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