Cannabis for chronic noncancer pain in patients prescribed opioids: efficacy questioned

By Nicole MacKee
Cannabis is often used by people with chronic noncancer pain who have been prescribed opioids, say Australian researchers, who have found that cannabis use neither improved pain nor reduced opioid use in this cohort. 

In their prospective study of 1514 people with noncancer pain who had been prescribed opioids, published in The Lancet Public Health, cannabis use was reported by almost one-quarter of participants (24%). The Pain and Opioids in Treatment (POINT) study found growing interest in using cannabis for pain relief among study participants, with interest almost doubling from 33% at baseline to 60% after four years. 

At the four-year follow up, the researchers found that, compared with nonusers, cannabis users reported greater pain severity (risk ratio 1.14 for less frequent cannabis users; 1.17 for daily or near-daily users), greater pain interference, greater generalised anxiety disorder severity scores and lower self-efficacy in managing pain.

The researchers also found no evidence that cannabis use reduced the use of prescribed opioids.

They noted that, due to the illegality of cannabis use during the study period (participants were recruited between 2012 and 2014), its use may have been under-reported. The medicinal use and supply of cannabis was decriminalised in Australia in 2016.

Dr Meredith Craigie, Dean of the Faculty of Pain Medicine, The Australian and New Zealand College of Anaesthetists, said there was great value in this in-depth, community-based study.

‘This study helps us to understand that what people have been doing isn’t working for all the people all the time,’ Dr Craigie told Medicine Today.

She said chronic pain was a complex condition, and there was a perennial search for an ‘easy fix’, but more research was needed into the specific active components of cannabis.

‘We are putting the cart before the horse in that the products are on the market, but we still don’t understand what these individual products are likely to do, and what doses we should recommend to which patients, if at all,’ she said, adding that industry had been reluctant to support independent scientific research efforts.

The authors of an editorial accompanying the research said it was important to avoid the mistakes made with opioids in finding a safer, more effective alternative.

Dr Craigie agreed. ‘We have a community living in hope that [cannabis] is the next “wonder-drug”, but we have to be careful that we are not promoting another range of harmful products, as occurred 25 years ago with opioids.’ 
Lancet Pub Health 2018; 3: e341-350.
Lancet Pub Health 2018; 3: e309-e310.