Resources


  1. Stockings E et al. Cannabis and cannabinoids for the treatment of people with chronic noncancer pain conditions: a systematic review and meta-analysis of controlled and observational studies. Pain. 2018 Oct;159(10):1932-1954 (PubMed)



Transcript

Dr. Frank Domino:

Eric is a 52-year-old patient who has had a problem with chronic low back pain for years. He's tried various pharmacologic and non-pharmacologic treatments for this problem. And yet, it persists. We have discussed the use of opioids for this. And he knows this is something I'm not interested in providing. He asks about using marijuana for his chronic back pain, he has a friend who has used it and found it very helpful. He knows that recreational marijuana is available, should he try to find it? But he wants my permission and my thoughts on whether it's gonna be beneficial or not.

Hi, this is Frank Domino, Professor in the Department of Family Medicine and Community Health at the University of Massachusetts Medical School, and joining me to discuss marijuana and its medicinal benefits is Alan Ehrlich, Associate Professor in the Department of Family Medicine and Community Health, Executive Editor of DynaMed. Alan, thanks for coming and bringing this interesting set of data forward.

Alan Ehrlich:

Hi Frank.

Dr. Domino:

So, not a week goes by without at least a few patients asking me what I think about marijuana and its efficacy for a variety of things but without a doubt, chronic non-cancer pain seems to be the most common reason that it's brought up. Can you help us understand what the data shows about this?

Alan Ehrlich:

Well, first of all, your experiences are matched by that of others. If you look at data from dispensaries based on surveys that have been done, the most common reason for someone to have a medical marijuana card in whatever state they may be in has to do with things like chronic low back pain and headaches and things like that. So these types of conditions, even though traditionally, these have not been what these medical marijuana laws have been passed are about, this is what in fact most people wind up using the substance for.

So, interestingly, there have been a couple of major systematic reviews that were done. There's one very recently published in Pain that looked at cannabis and cannabinoids for the treatment of chronic non-cancer pain conditions and they really searched far and wide, as a systematic review should, and they gathered both randomized trial data as well as observational data and together they found over 100 trials or studies. The total number of patients involved in these was almost 10,000.

What they did was they looked at various ways of measuring the effect on pain and you can measure that in a couple of different ways. One is you can look at what was the average pain reduction. So if you're using let's say a zero to 100-point scale, you can say, "Well there was a reduction of five points or 15 points." That's one way of doing it. And that looks at averages. The other way is to say, "How many patients achieved a 30% reduction in their pain or a 50% reduction in their pain?" And then you get, either you did or you didn't and off of that, you can often calculate a number needed to treat.

Dr. Domino:

Okay, so this was a systematic review that went far and wide to identify data. Can you tell me what the outcomes were?

Alan Ehrlich:

So they found that using cannabinoids, in any form, for the treatment of chronic non-cancer pain resulted in higher rates of people achieving 30% reduction in their pain. They use odds ratios to calculate this and their odds ratio was about 1.5. For the 50% reduction in pain, they found a similar degree of responders although there were wider confidence intervals and the net effect was that it wasn't statistically significant for that outcome.

When they looked at the mean change on 100-millimeter visual analog scale, they calculated the mean difference across all the people enrolled was only about 3 millimeters, so not much of an effect on the means, and that's because the responder rates weren't that different. The net effect in percentages was probably about 4% or 5%, so ultimately, you'd get a number needed to treat around 24 or 25, something like that.

Dr. Domino:

So from what I hear you're saying there possibly was a decreased risk of pain at the 30% responder rate, but that degree of pain reduction was fairly small, three in 100, is that right?

Alan Ehrlich:

Not quite frank. So what you're looking at there is when you say the three in 100, that's going across all the people including people who did not achieve benefit. So it's easier to say, are there sub-populations that might benefit even if other people perhaps don't get a meaningful benefit or get harms and wanna stop and things like that? So looking at a mean number for something like this can sometimes be misleading.

Dr. Domino:

Very good, I appreciate you clarifying that. So one of my patients uses cannabidiol spray on his back and another puts drops under his tongue. What is cannabidiol and why has it been in the news lately?

Alan Ehrlich:

So if you think about the herbal plant cannabis, it has a number of different cannabinoid chemicals which all have the potential to interact with our endocannabinoid system that affects a variety of things including pain perception and immune function and things like this. THC is the one we are most common... We are most familiar with, and it's what gives people who smoke marijuana that high, that psychoactive sensation. Cannabidiol does not have any of those properties and it has an effect where it tends to regulate the bodies perception of the effect of marijuana but it also has some beneficial effects, and most notably it has been shown to be useful in the treatment of certain medication resistant pediatric epilepsies. Recently, there was a medication called Epidiolex that was just approved for this. And in response to this, the FDA has changed the classification of cannabidiol from Schedule 1 to Schedule 5, meaning very little potential for abuse.

Dr. Domino:

Okay, so... But my patients don't have pediatric epilepsy. Why are people using it for so many other conditions?

Alan Ehrlich:

Well, like so many other things, Frank, people use it for just about anything and see what happens. And there's, in fact, no evidence that cannabidiol has any value for chronic low back pain. Going back to even the studies that were done, there's such a wide variety of conditions that are looked at but primarily the evidence from all... From the highest quality evidence is focused almost entirely on patients with MS pain, or patients with neuropathy. And when you talk about chronic low back pain, there's virtually no evidence from any type of randomized trial or any other high-quality, even a cohort study, demonstrating real benefit.

Dr. Domino:

Okay. I did see somewhere, I believe from one of my psychiatric provider friends, that cannabidiol is used to treat chronic anxiety. Is there any data in this world?

Alan Ehrlich:

So there has been some studies around this, but there have been no randomized trials, and one of the problems with the use of cannabinoids, I'll speak more broadly, for anxiety is that it has the potential both to help with anxiety, and to cause anxiety, and so there's a little bit of an idiosyncratic response and you've got to be very careful if your patient is going to try that for that condition, that they're in a situation that's safe, there are other people around so that they don't start having a bad reaction and doing something because of that.

Dr. Domino:

Okay, so we have Eric here and he wants to know what he should do about his chronic back pain with regards to marijuana, what advice can we give him?

Alan Ehrlich:

So I think the first thing is to let him know that there's no high quality evidence in support of marijuana as being effective for this. That being said, there's obviously a lot of anecdotal data and the absence of evidence of benefit is not the same as evidence that there is no benefit. And so that's important to keep in mind. And so Eric may be like millions of other Americans who decide I'm going to try this and see if I find benefit and he may get a placebo effect, he might get a real effect, we don't know, but I think the main thing is we're now in a time where patients do have the ability to try this, again, in many of the states where it's legal. And so you wanna make sure that you are staying engaged with him. If he's going to try it, get him to commit to upfront. How will you know if there's benefit? Is it that you have better sleep? Is it that you're able to work? If he is going to use it, is he going to use it when he goes to work? That would be a bad idea, most cases, depending upon what work he does, but he shouldn't be driving after he consumes marijuana. There's all sorts of conversations like that to make sure that if there is some possible benefit that he's going to receive, you wanna minimize any harms that may be associated with the use of marijuana.

Dr. Domino:

Alan, thanks so much. This helps a great deal. And until we get better evidence I think your words are very wise.

Practice pointer. A recent large, systematic review continues to find very little or no evidence for the use of marijuana for chronic low back pain or many other conditions. Join us next time when we discuss the evaluation of breast pain in women, and the role imaging plays in its evaluation.