New Study Tells Nothing About Marijuana’s Role in Heart Disease

  • by Mitch Earleywine April 24, 2014

    A new study on marijuana appeared in Journal of the American Heart Association. These are interesting data, but we have to interpret them very carefully.

    Sure, we know cannabis can raise heart rate briefly, but most users develop tolerance to the effect. We’ve also seen (in a much larger sample) that it doesn’t increase mortality rates even among survivors of heart attacks.

    But the new study made the news anyway. Investigators specifically searched a French database where physicians are legally bound to report any drug-related case that they view as “leading to temporary or permanent functional incapacity or disability, to inpatient hospitalization or prolongation of existing hospitalization, to congenital anomalies, or to an immediate vital risk or death.”

    They then looked for cannabis users and found a shade less than 2,000 in the past 5 years. It’s impossible to know what that number means without knowing the number of people these physicians saw or how many patients used cannabis and did not end up reported to this database.

    They then found a whopping 35 of these who had cardiac complications. It is impossible to know what to make of this number without knowing the number of cannabis users in France, which the authors report is 1.2 million. If you divide 35 by 1.2 million you get roughly .00003. I’m guessing that not all these cannabis users went to the doctor and not every person who used cannabis and had cardiac complications fessed up to the doctor, so let’s say that we’re off by two orders of magnitude. Let’s give the prohibitionists the benefit of the doubt and multiply by 100. That’d put the rate of problems up to .003.

    If those are the chances of having cardiac complications as a French cannabis user, my first thought is that using cannabis protects people from cardiac problems. We need a comparison group of people who don’t use cannabis to know their rate of cardiac problems, but, as the authors point out, we simply don’t have those data. The closest estimates were 57 per 10,000 people, based on another study, which is .0057, or almost twice as bad as the rate among the cannabis users (after our generous overestimation). I’m not going to hold my breath for the the headline, “Cut your heart disease in half with cannabis.”

    In short, this study tells us a lot about what kinds of cardiac complications appeared in people who were reported to the French government for cannabis-related problems, but tells us little about the link between cannabis use and cardiovascular disease.

    47 Responses to “New Study Tells Nothing About Marijuana’s Role in Heart Disease”

    1. bobwv says:

      I’ve been hearing this on the news.Ten years ago when the doctor was telling me about my heart problem he stopped halfway in a sentence and walked out of the room. Guess he recenyly lost someone close.

      When my pressure is too high I burn one and it brings it down. When my pulse is racing I burn one and it comes down. I think I’ll keep using.

    2. Galileo Galilei says:

      They are really grasping at straws now. The prohibitionists can’t ignore the science anymore, so they’re desperately combing through scientific studies to find this kind of stuff.

    3. anon says:

      Great blog! Everytime there is a negative study about cannabis, I come to this website to find out the whole truth.

      I especially look out for Dr. Mitch Earleywine’s blogs. Thanks, and keep at it!

    4. Harper Ennis says:

      First they ignore you, then they laugh at you, then they fight you, then you win.

      Mahatma Gandhi

      I think we get a little closer to winning everyday!

    5. Marty says:

      If the Feds would get off their asses and reclassify MJ to a lower risk than it now is, then MAYBE we can start to get more non biased info on its potential medical benefits (and harm if any).

    6. phrtao says:

      There seems to be a trend with these ‘medical findings’. If you ever get any news that cannabis can help with a medical condition (such as aiding a patient in cardiac arrest ) you also find a study that completely contradicts it like this one. It is a basic disinformation tactic to create confusion and obscure the truth. Disinformation plants the doubt in people’s minds so that is why there are always some people who are undecided about medical cannabis and some that think it is a bad thing. Without the disinformation there would 100 % support for this wonder drug not the 75 % or so there is now !

    7. Dear Dr. Earleywine,
      I’m a MD, and president of Italian Association for Therapeutic Cannabis (Associazione Cannabis Terapeutica). I think that I’ve found a little error in your article. You wrote about the rate of cardiac problems between the non-users: “The closest estimates were 57 per 10,000 people, based on another study, which is .0057″. But in the study we find: “average incidence rates of myocardial infarction and coronary deaths in patients aged 35 to 44 years were estimated to be 57 of 100 000 among men”. So the real number is .00057; not “almost the twice” of the cannabis users, but ten time less. I hope I’ve made a mistake…

    8. Kaylinn says:

      This article is truly terrible. As a clinician I want to see MJ leagized, but when you are extrapolating information from clinical trial that had nothing to do with MJ in the first place I don’t believe it. Further more we have no evidence of what diet and exercise regimen these patients were on which is clearly tied to heart disease. Also the rate of heart disease in known to be lower in Europe. Further more the 57 per 10,000 study you were talking about, could have included cannabis users, but we won’t know because no one asks. No conclusions can be drawn from this for us Americans. Need double blind, placebo controlled studies to make appropriate conclusions!

    9. grant says:

      i am with Dr. Crestani, Dr. Earleywine may be a great doctor but his math is lacking. :)

    10. Dr. Mitch Earleywine says:

      Dear Dr. Crestani-
      You’re right! Sorry for the error. My joking hypothesis about cannabis as a protector just became more tenable! Thank you so much for pointing out the mistake.

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