> If you did this in a randomised controlled trial, you might recruit 1000 patients, and randomise 500 to this new drug and 500 to placebo. If you ran the trial

> If you did this in a randomised controlled trial, you might recruit 1000 patients, and randomise 500 to this new drug and 500 to placebo. If you ran the trial for a year, you might find 1% of the placebo arm died, and only 0.5% in the control arm. This demonstrates a risk reduction of 0.5%, or a NNT of 200. That's because the only thing you've learned during the above trial is that it halves the death rate for one year. You have no idea what happens after that year. It could get better, worse, or the adverse effects would be worse than the cure. Your assumption that that drug cuts the death rate beyond that single year is an assumption, not a fact. > An NNT, by conventional teaching, is underwhelming. As it should be. That's the only thing you can conclude from the trial. > Is this the right way to think about it? ABSOLUTELY NOT! The high NNT is a consequence of a low event rate, NOT an ineffective therapy. Yes. The absolute proven benefit is miniscule. > In preventative medicine, where everyone will EVENTUALLY die of something (and 25% the thing you are looking at), it is the RELATIVE risk reduction (50% here, not 0.5%) that matters. But you've only had a 1 year trial. Drugs often have long term adverse effects that dwarf the benefit. As an example, when steroids were first discovered they were viewed as miracle drugs and given in massive doses. It didn't take long to understand the adverse effects were far worse than the symptoms it was treating. Today we are far more careful with steroids. Similarly with Aspirin, or any number of very useful drugs. So the question is what gives you the confidence to make any claims beyond what the trial showed?