Cannabis and pain

In 1999, what was then the Institute of Medicine (now the National Academy of Medicine) issued a report that mocked the idea that smoking plant material could ever be considered medicine but cautiously endorsed research into the possible therapeutic utility of either natural or artificial cannabinoids.  A few years later, “drug czar” Barry McCaffrey dismissed the whole idea as “Cheech and Chong medicine.”

Things have changed.

A new National Academies report makes an unequivocal finding:


There is substantial evidence that cannabis is an effective treatment for chronic pain in adults.

It also finds that some patients are replacing opiates with cannabis.

On average, the pain control benefits of cannabis are described as “modest.” And the data are – for reasons the report lays out – still frustratingly inconclusive about which chemical components of cannabis are doing the work and what dosage regimens and routes of administration are most effective. Still, the finding is what it is.   The sound you hear in the background is the gnashing of drug warriors’ teeth.

Pain is the most common indication cited when physicians and other heath practitioners recommend cannabis under state medical-marijuana laws. It is also the hardest symptom to measure objectively, and thus the easiest to fake for someone who merely wants legal permission to get stoned. So whether a state allows medical-marijuana recommendations for pain is one of the key dividers between “tight” versions of medical marijuana, intended to serve genuine patients only, and the “loose” versions (more common west of the Mississippi) that amount to de facto legalization. Advocates of “tightness” have often won the argument  by pointing out that the efficacy of cannabis for pain hadn’t been scientifically demonstrated. It’s going to be much harder to keep a straight face while saying that tomorrow than it was yesterday. And the finding comes just as several new states (including Florida) are in the process of implementing voter-approved medical marijuana laws.

There’s much more to the new report than the pain finding; so far I’ve only skimmed it. But it’s clear that the politics of medical marijuana just took on a new shape.

Author: Mark Kleiman

Professor of Public Policy at the NYU Marron Institute for Urban Management and editor of the Journal of Drug Policy Analysis. Teaches about the methods of policy analysis about drug abuse control and crime control policy, working out the implications of two principles: that swift and certain sanctions don't have to be severe to be effective, and that well-designed threats usually don't have to be carried out. Books: Drugs and Drug Policy: What Everyone Needs to Know (with Jonathan Caulkins and Angela Hawken) When Brute Force Fails: How to Have Less Crime and Less Punishment (Princeton, 2009; named one of the "books of the year" by The Economist Against Excess: Drug Policy for Results (Basic, 1993) Marijuana: Costs of Abuse, Costs of Control (Greenwood, 1989) UCLA Homepage Curriculum Vitae Contact:

5 thoughts on “Cannabis and pain”

  1. The report on chronic pain bases much of its evidence claim for cannabis for chronic pain on… which was a systematic review of cannabinoids for medical use and covered a considerable number of indications. That review looked at 28 studies with 2454 participants, but only two studies were assessed as having a low risk of bias, 9 as unclear risk, and 17 as high risk of bias. And the pooled odds ratio for having a 30% reduction in pain was only 1.41, which is OK but not fantastic.

    One of the more interesting studies in the report (not on chronic pain) was the Bradford study… on costs incurred by Medicare Part D in states with and without medical marijuana laws. They were lower in states with medical cannabis laws. It was a very complex study involving some sophisticated use of large databases and some sophisticated statistical analysis. It was using medical marijuana laws as a surrogate measure of medical marijuana use in different states with different laws. Since many people in states without such laws use cannabis for self-reported medical reasons, the cost differential in that Bradford article could actually be a conservative estimate of the prescription drug savings.

    Nevertheless, the report is timely. We do not know yet what policies the Justice Department is likely to pursue under President Pence, but this report does seem to create a barrier to any retreat to the good old days of DEA enforcement.

  2. "Modest" evidence really is about right. That meta-analysis which pooled data on the 30% pain reduction and came up with an odds ratio of 1.41 is a modest effect size. However, odds ratios tend to inflate "relative risks" when the outcome of interest occurs frequently; in this setting, the "relative risk" could be framed as a response ratio for cannabinoids versus placebo, which would be the frequency of 30% pain reduction in the cannabinoid group divided by the frequency of the same response in the placebo group. Using the Cochrane RevMan software to look at the same trial data, I can replicate the odds ratio of 1.41. With a click of the mouse, I get a pooled response ratio of 1.23, which is something but is not a whole lot. The 30% pain reduction was present in 37% of the cannabinoid group, which is sort of in the low middle of the range of pain responses for most pharmaceutical analgesics for chronic pain.

    Therefore it seems to me that the NAM has placed an optimistic spin on the data by calling it "substantial evidence." Only one of the studies used smoked marijuana and the other seven studies used nabiximols (trade name Sativex), which is still awaiting FDA approval in this country. The smoked cannabis study… enrolled participants with painful HIV neuropathy (the placebo cigarettes were identical with "the cannabinoids extracted") Not sure how that will work because I do not know how much the cannabinoids contribute to the distinct aroma of the smoke.

    A miracle it ain't. But it is worth doing better research, which is the main point of the NAM report.

  3. Pain may be difficult to measure objectively, but not SUBJECTIVELY. When you're in pain, you know it. It makes everyday activities more difficult or impossible. When something reduces or eliminates your pain, you know it. So I still fail to understand how or why our government, or doctors for that matter, have any right or authority to tell you otherwise, or worse yet, punish you for doing something to reduce your pain that they don't approve of. Why would they even want to?

    Also, as pointed out at the end, that report covers a LOT more than just pain. Any one who says we need more research is clearly not aware of the HUGE amount of research that's already been done.

  4. I had expected this story to be reported on the news, but I have not heard a single story about it. And it appears to have generated little interest in the RBC. I wonder why that is. Also, when NHTSA published "Drug and Alcohol Crash Risk: A Case-Control Study, ", reporting that alcohol but not THC was associated with car crashes, there was media silence. We discussed that study in journal club today with a researcher who has just received a grant to study THC and driving behavior, and even though it had a couple of limitations, it did not appear to have any fatal flaws.

    Very odd, the apparent public indifference. Does evidence-based public policy still matter to anyone?

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