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While trials can determine that on average there is no adverse effect it does not necessarily imply that no individual would experience any negative effect. It
by fspeech 5y ago
While trials can determine that on average there is no adverse effect it does not necessarily imply that no individual would experience any negative effect. It is possible that the negative effects experienced by some are cancelled out by positive effects experienced by others. If the effect is reversible, one can prove causality by giving an individual both placebo and the drug, in sequence, without the subject knowing which is which.
- carbocation 5y agoYes, a crossover trial design would be one way to address that. For example, various side effects have long been attributed to statins. This was tested in a trial published very recently in a placebo controlled crossover design, which found that the effect attributed to statins has probably been overestimated[1]. (They found no significant difference between placebo and statin; but, by eye, I would be willing to agree with a skeptic that it looks like there is probably a difference that is just too modest to identify at statistical significance at this sample size.) I should add that the original article being discussed is making claims that would not require any crossover trial to identify. If lowering cholesterol doesn't cause numerically higher suicide or depression, then the author's point is invalidated. 1 = https://www.jacc.org/doi/10.1016/j.jacc.2021.07.022 https://www.jacc.org/doi/10.1016/j.jacc.2021.07.022