Originally Posted by
OrphanPip
It's unfortunate that medical studies can't be perfect, but nothing really is in this world. If we are to get anywhere in life, whether it be in medical treatment or any other aspect, we have to take risk sometimes.
The standard size of a phase III clinical trial is around 2000 individuals, this is more than enough to have statistically significant results. Occasionally you'll miss out on the 1/1,000,000 complication, like with the Vioxx debacle, but for the most part clinical trials are more than enough to determine safety and efficacy. We can't forget about the large number of animal trials that are performed prior to it getting anywhere near a human being. Most medications will have unfortunate side effects, but it is up to the patient and their physician/psychiatrist to discuss and decide whether the risk is worthwhile to them.
As to all variables not being considered, they consider as many variables as is reasonably possible. Eventually, you have to stop wondering if the humidity levels in the air have an effect on a condition, it's unreasonable to consider "all variables". The system isn't perfect, but it is damn near as good as we'll ever get.