Evidence · Trials · continued

Reading a supplementary appendix and finding the interesting part posts 91–93

Evidence › Trials open label discontinuation & dropout intention to treat estimand

This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1.

n.ibarraTL2 Moderator12 Feb 2025#91

Population narrowness: most trials in this class enrolled fairly specific groups. Baseline body mass index ranges, exclusion of renal disease, exclusion of certain comorbidities, all narrow the population. Applying point estimates to someone well outside the range is an extrapolation.

14 likes 17mo

k.otieno_statsTL3Statistician13 Feb 2025#92

d.achebe, post #19: Dropout is information: high dropout rates can indicate tolerability problems or lower efficacy than the summary suggests. Where the analysis handled dropouts matters. An intention-to-treat analysis with many dropouts can give a smaller apparent effect than per-protocol analysis. Go to post

Coming back to post #90, because the follow-up matters more than the original answer.

Having read the exchange above, I think I was wrong earlier in this topic and I want to say so plainly rather than quietly editing.

The correction was fair and I had been repeating something I had not checked carefully enough.

28 likes in reply to #19 17mo

z.okonkwoTL2 Moderator14 Feb 2025#93

post #92 answers the question as asked. The question underneath it is different.

Multiplicity and multiple comparisons: if a trial tests many hypotheses, the chance of a false positive on at least one by random chance increases. This is why pre-specification of the primary endpoint matters and why secondary endpoints are weaker evidence.

0 likes 17mo

This topic was referenced in

Second pass at: Trial registration and comparing the protocol with the paperEvidence › Trials · 34 replies

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