A Canadian study appears to give medical cannabis the thumbs up for safe use among patients suffering from chronic pain.
Published in the Journal of Pain on Sept. 16, the study found that chronic pain patients who used medical marijuana every day for a year – given they were carefully monitored – did not experience an increase in serious adverse events compared to patients who did not use the treatment.
The research, a national multicenter study, was led by Dr. Mark Ware of the Research Institute of the McGill University Health Center (RI-MUHC) in Montreal, Canada.
The team followed 215 adult patients with chronic non-cancer pain who used medical cannabis, comparing them to a control group of 216 patients of chronic pain who did not use cannabis. They focused on seven clinical centers in Canada with an expertise in pain management, namely centers in Fredericton, Halifax, London, Montreal, Toronto and Vancouver.
Dr. Ware highlights their study, done from 2004 to 2008, as the first and largest one to be made on the long-term safety value of medical marijuana in the arena of pain management.
“We found that medical cannabis, when used by patients who are experienced users, and as part of a monitored treatment program for chronic pain over one year, appears to have a reasonable safety profile,” Dr. Ware said in a press release.
The study participants in the cannabis group were given herbal cannabis with 12.5 percent of the active ingredient tetrahydrocannabinol (THC), with an average of 2.5 grams of cannabis consumed a day in smoked, vaporized or edible form. They underwent lung function and cognitive testing, some with blood tests, and were asked about their pain levels, mood, and quality of life over the course of one year.
While quality-controlled herbal cannabis “appears to have a reasonable safety profile,” the researchers record an increased risk of non-serious side effects, such as headaches, dizziness, and respiratory issues linked to smoking.
Dr. Ware noted the limitations of their research, where patients were self-selected and not randomized, and were most participants were experienced medical marijuana users. The study, he said, cannot conclude about the safety of cannabis in new users.
In addition, the team admitted to not being able to separate out the effects of tobacco, nothing that many of the medical-grade marijuana users also smoked tobacco or combined it with the medicinal weed.
"We couldn't tease out what was just a pure cannabis smoking effect and what was tobacco. So we recommend caution in terms of smoking," explained Dr. Ware.
Along with supplementary material, the study will be published in the journal's print version in October this year.