Pubdate: Thu, 14 Dec 2017
Source: National Post (Canada)
Copyright: 2017 Canwest Publishing Inc.
Author: Geordon Omand
Page: A8


Drug may do more harm than good, say critics

VANCOUVER * There is little to no research to support the supposed
benefits of medical cannabis, and what evidence exists suggests that
using marijuana as medicine may do more harm than good, family
doctors' associations across Canada are telling their members.

A trio of advisories prepared by the Alberta College of Family
Physicians has been distributed to more than 32,000 clinicians,
summarizing the scientific literature, or lack thereof, around
medicinal marijuana.

"One thing that was quite consistent was adverse events," said Dr.
Mike Allan, a professor of family medicine at the University of
Alberta in Edmonton. "And the benefits, even if they're real, are much
smaller than what people might anticipate."

Allan co-ordinates the college's biweekly updates, "Tools for
Practice," which focus on topical issues and are circulated through
professional chapters in every province except Quebec and Newfoundland
and Labrador.

The three most recent updates were inspired by physicians wanting to
know more about the research behind medical cannabis. Family doctors
are facing increasing pressure from patients asking about medicinal
pot and the college wants to ensure its members have the information
they need to make informed decisions around treatment, Allan said.

"I think this gives ( doctors) some comfort, saying, ' Look, here's
the evidence. It's actually missing in a lot of places, so I can't
give it for conditions X, Y and Z,' " Allan said. He described medical
pot as a high-risk product that should only used in rare
circumstances when other, safer treatment options have been exhausted.

Health Canada data show the number of clients registered with licensed
medical marijuana producers jumped to more than 200,000 as of June
2017, which is about 2.7 times greater than  the 75,166 people
registered at the same time last year. Registrations more than tripled
in both 2016 and 2015.

"The decision to use cannabis for medical purposes is one that is made
between patients and their healthcare practitioners, and does not
involve Health Canada," department spokeswoman Tammy Jarbeau said
Tuesday in an email.

Health Canada published a lengthy information bulletin for medical
professionals about the benefits and harms of medical marijuana,
topped with a disclaimer warning that cannabis is not an approved
therapeutic product and the department does not endorse its use. The
document was last updated in 2013.

The first advisory prepared by Alberta's family physicians college,
which was released Nov. 14, says the evidence is "too sparse and poor"
to conclude that marijuana is effective at relieving pain. The second
document, released two weeks later, describes "adverse effects" as one
of the only consistent findings of the existing studies. These harms
included hallucinations, paranoia, dizziness and l ow blood pressure.

The research likely underestimates the frequency of adverse outcomes
because most studies involve patients who have a history of using pot
so are less likely than the average person to experience any negative
side effects, Allan said.

Some studies indicate marijuana can reduce nausea for chemotherapy
patients and control spastic muscle contractions in patients with
multiple sclerosis, but there is virtually no evidence of any effect
on chronic anxiety or glaucoma, as is commonly cited by industry advocates.

"Some of the pain studies go for nothing more ... than five, six
hours. And this is for chronic pain," Allan said. "It's hard to get a
great feel for how someone is going to do long term on a medicine
after five, six hours."

The only evidence of marijuana being used to treat glaucoma is a
single randomized study conducted on six patients, he added.

Medical colleges have released some general guidelines for primary-
care providers about prescribing marijuana. Documents released by the
colleges of physicians and surgeons in both British Columbia and
Alberta cite the absence of reliable evidence demonstrating the
effectiveness of cannabis as medication.

The Alberta college is helping put together more comprehensive
provincial guidelines for prescribing medical cannabis, which it
expects to release by March, Allan said.
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