Last updated July 11, 2018 at 2:33 pm
Australian study suggests drug might not do much for pain.
As the debate around medicinal cannabis heats up, new research in the use of the drug for pain management, one of the world’s longest in-depth community studies yet, has left the scientific position as muddy as ever.
The research by the University of New South Wales (UNSW) examined the effects of cannabis on 1,500 people prescribed opioids for non-cancer pain over a four-year period, but there were no strong findings supporting a clear role for the drug in relieving pain.
But the results were complicated. Participants who used cannabis had a greater pain severity than those who didn’t use cannabis. They also had increased anxiety, were coping less well with their pain, and reported that pain was interfering more in their life.
Participants were interviewed at the beginning of the study and then every year for the next four. They were asked about chronic pain over the previous year and its impact on sleep, daily life, working ability, and social interaction.
Over the time interest in cannabis for pain relief rose from 33% of participants at the beginning of the study up to 60% of participants at the four-year mark. By the end of the study, almost a quarter of participants had used cannabis for pain.
As cannabis was only approved in Australia for medical purposes in October 2016, well after the study recruitment process had closed, many had accessed illicit cannabis. This meant the cannabis was likely consumed without guidance of a medical practitioner, with unknowns around dosage, quality, or expectations.
The authors also note that “it is not surprising that two of the main reasons for discontinuing cannabis use for pain were access difficulties and legal concerns”.
Complex care needs
But by the end of the study, most participants reported that cannabis had no effect on their use of opioid medication – a major hoped-for benefit of making medicinal cannabis available. Many had abandoned its use, but for other reasons.
Lead author of the study, Dr Gabrielle Campbell, said the study showed the need for caution.
“Care needs to be taken in advising patients about expectations of cannabis for their pain, management will be complex, and it’s unlikely that one strategy will work for everyone,” she said, adding that the use of cannabis use for noun-cancer pain needs a multidisciplinary approach.
Cannabinoids are typically used in adjunction to other medications, not as the frontline drug for pain management.
“It’s a real-world study, [we] have been looking at doing maybe more experimental studies to determine the interactions of the two drugs,” said Professor Michael Farrell, Director National Drug and Alcohol Research Centre at UNSW Sydney and an Investigator on this study
Future studies might involve controlled doses, and higher quality doses.
Several guidance documents for medicinal cannabis can be accessed through the TGA.