Medicinal cannabis may not be as effective in relieving chronic pain according to one of the world’s longest community studies, however other research has shown the drug beneficial for children with epilepsy.

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The research published in Lancet Public Health showed there was no clear evidence that cannabis led to reduced pain severity or pain interference or led participants to reduce their opioid use or dose.

The University of NSW (UNSW) four-year study of 1,500 people was funded by the National Health and Medical Research Council (NHMRC) and led by the National Drug and Alcohol Research Centre (NDRAC).

Study participants had been in chronic pain for on average 10 years and taken prescribe opioids for four years. There were very high rates of physical and mental health problems.

Researchers examined the effect of cannabis on participants’ pain, on the extent to which pain interfered with their everyday life and on their prescribed opioid use.

Results showed those using cannabis had greater pain and anxiety, were coping less well with their pain and reported that pain was interfering more in their life, than those not using the drug.

“Chronic non-cancer pain is a complex problem. For most people, there is unlikely to be a single effective treatment,” UNSW lead author Dr Gabrielle Campbell said.

In a pioneering study three-quarters of Australian parents of children with epilepsy treated with medicinal cannabis from the black market overwhelmingly reported the drug as effective.

Cannabis has showed proven medical benefits in treating drug-resistant epilepsy in children, chemotherapy-induced nausea and multiple sclerosis.

In the University of Sydney study children were treated with generally lower doses of cannabis than commonly considered a therapeutic dose successful in clinical trials.

“And despite the overwhelming presence of generally low levels of THC, concentrations did not differ between samples perceived as ‘effective’ or ‘ineffective’,” University of Sydney School of Psychology’s Ms Anastasia Suraev said.

Just over half were associated with a 75-100% reduction in the occurrence of seizures; and 65% had other beneficial effects such as improved cognition (35%) and language skills (24%).

“Our findings highlight the huge unmet clinical need in the management of treatment-resistant epilepsy in childhood,” Ms Suraev said.

The research was published in journal Scientific Reports.

Medicinal cannabis was legalised in Australia in February in 2016 through a doctor- prescribed special access scheme.

A recent survey of Australian GPs showed while the majority supported medicinal cannabis being available on prescription, most admitted they didn’t know enough about prescribing it for their patients.

More than two thirds of GPs had at least one patient enquire about medicinal cannabis in the three months prior being surveyed. Fewer than one in 10 knew how to navigate the processes to prescribe. The majority reported they felt uncomfortable discussing medicinal cannabis with their patients.

The research published in British Medical Journal Open found most GPs supported the use of medicinal cannabis for: chronic cancer pain (80.2%); palliative care (78.8%); and intractable epilepsy (70.3%).

A majority of GPs considered medicinal cannabis should be available by prescription, with the preferred model trained GPs being able to prescribe independently of specialists.

Author and Academic Director of the Lambert Initiative Professor Iain MacGregor said GPs lacked the support needed to handle patient enquiries about medicinal cannabis. “GP education and training are urgently needed. Our survey demonstrates many GPs have fielded recent enquiries about medicinal cannabis from their patients –yet most feel poorly informed and inadequately trained around medicinal cannabis and its current regulation and uses.”

Fewer than 800 patients had accessed legal medicinal cannabis in Australia.

Part of the problem was the specialist-based model largely excluded GPs from prescribing, Professor MacGregor said.

“This situation continues to frustrate patients, many of whom simply continue to access illicit cannabis to self-medicate.”