Generalizability vs. Transportability in Trials

Not quite sure what you’re getting at? There’s a difference in the event rate between arms of an RCT. The fact that this difference will change from trial to trial, even if the trials are designed identically, makes the notion that there’s a universal “NNT” for a given therapy very problematic (?) Contrast these trial-based risk differences with the absolute reduction in risk that we might estimate for an individual patient in our clinic if he were to be offered treatment in the post-trial setting. I’m just saying that these trial-level risk differences will not necessarily translate to the risk reduction that our individual patient might expect (yet this is what the “NNT” is suggesting we should do…).