The remaining major flaw, which is also related to sample size, is the importance of randomization. The value of randomization is that it helps to minimize the chance that the subjects who’ve been enrolled are sufficiently different, between the two groups – in some way that the investigators may not even have realized could matter – as to affect the results. For example, let’s imagine testing a new medicine for depression.
Explore This IssueACEP News: Vol 32 – No 08 – August 2013
Suppose we look at the two groups and find that the active treatment group did better than the placebo group. But then suppose we go back and ask all the subjects whether, during the study, they happened to acquire a new boyfriend or girlfriend, and it just so happens that far more in the active treatment group than in the control group say yes. We would then have no idea whether they felt better because of the new relationship or the treatment, or whether the treatment helped them get into a new relationship. This is what is called a “confounder.” The effect of randomization is to minimize the role of confounders, and the larger the sample size, the more effective randomization is in accomplishing this.
So now that you know the three major flaws, let’s look at the results. Of the 11 subjects in the cannabis group, five achieved “complete remission,” meaning short-term symptomatic improvement, while this was achieved for only 1 of 10 in the control group. Looks like a big difference, right? Well, because the sample size is so small, statistical calculations tell us there is a 43% likelihood this difference was due purely to random chance! Thus, for the primary outcome measure, the main thing investigators were testing for, they found no difference with active treatment. The most positive spin you can put on this, while maintaining scientific objectivity, is that there was a “trend” toward improvement that might turn out to be real in a larger study. To their credit, part of their conclusion says a larger study should be done, and a “non-inhaled” form of the drug should be tested. But that did not deter them from spinning the results as positive: Cannabis “produced significant clinical benefits … without side effects.”
That last phrase didn’t quite get me to laugh out loud, but I did find it quite amusing. “Without side effects?” That is nothing short of hilarious. Any effect of a drug that is not the intended effect is, by definition, a side effect. And so all of the effects of smoking marijuana that were not related to ameliorating the symptoms of Crohn’s Disease were side effects. Anyone who knows even a little about marijuana knows that users experience several completely unrelated effects. These may not have been side effects that caused subjects distress or made them decide to drop out of the study. But they were most definitely side effects.