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  "path": "/t/generalizability-vs-transportability-in-trials/28551?page=3#post_56",
  "publishedAt": "2026-03-01T18:42:08.000Z",
  "site": "https://discourse.datamethods.org",
  "textContent": "Suhail- I’m not disputing the practice of combining an _individual_ patient’s estimated baseline risk for an event with an RCT-derived OR in order to estimate the _personal_ absolute risk reduction he might expect with therapy. Rather, I’m disputing the idea that a _group_ -level ARR, as derived from an _RCT_ , can be “translated/transported” (or whatever the right word is) to an _individual_ patient in the postmarket setting to estimate his _personal_ ARR.\n\nWithin-arm event rates will _differ_ between trials, as will the between-arm _difference_ in event rates, even when the trials are designed identically. Therefore, **the NNT calculated from these identically-designed trials plausibly might end up differing substantially (!)**\n\nI’m highlighting the fact that the ARR derived from an RCT is a _group_ -level assessment of absolute risk reduction that should NOT be conflated with the absolute risk reduction that an _individual_ patient in the postmarket setting might incur. An RCT-derived ARR reflects the covariate distribution of its underlying convenience sample and this distribution can change from trial to trial. Therefore, “NNT” is highly situational and dependent on features of the recruited convenience sample. As such, NNT should NOT be “transported” to _individual_ patients in the postmarket setting for the purpose of therapeutic decision-making (?)",
  "title": "Generalizability vs. Transportability in Trials"
}