SURMOUNT-4 and what withdrawal data does and does not tell an individual — one year on posts 91–120

The honest answer on SURMOUNT-4 is that it depends, and the useful part is the list of what it depends on. Four items, in rough order of how much they matter.

Most people get the first two right and then argue about the fourth.

The arithmetic in post #89 is right; the assumption feeding it is the part to check.

Checked the SURMOUNT-4 claim against the primary source this morning. It survives, with a narrower scope than the version quoted here. Posting the narrower scope.

The 2.5 mg starting dose is a tolerance step and not a therapeutic one. Judging efficacy at that dose is the single commonest reasoning error in this subcategory.

Two people can read the same figure differently here and both be reasonable.

Gastrointestinal effects were comparable in character to the GLP-1 monoagonists across the programme. Individual reports here vary in both directions, which is what you would expect from a between-person difference rather than a between-drug one.

Agreed, and I will stop repeating the version of this I had been repeating.

Narrowing post #93, because the general version has more than one answer.

The five maintenance doses in the tirzepatide programme give a genuine dose-response curve, which is unusual. Most trials in this space compare one or two doses against placebo and cannot say anything about the shape of the relationship.

I have changed my mind on this once already, so take it as current rather than settled.

Storage and stability: published data on licensed tirzepatide formulations exists and is worth reading directly rather than through summarised claims. Reconstituted preparations in different diluents have not been studied and extrapolation from the licensed formulation is the best you can do.

On SURMOUNT-4 I would separate what is worth knowing from what is worth acting on. The first list is long and the second is short, and conflating them is how threads get heated.

On post #97 — agreed on the reasoning, with one qualification.

SURMOUNT-4 used a randomised withdrawal design: everyone titrated, then those on maintenance were randomised to continue or placebo. Continuation maintained effect; withdrawal was followed by regain. The finding is robust but it says nothing about a lower effective maintenance dose, because that was not studied.

That holds under the stated conditions and I have stated them.

Where the SURMOUNT-4 discussion usually stalls is that nobody wants to say "I do not know" and everyone is willing to say "it varies". Those are the same sentence with different clothes on.

Adding a reference point for SURMOUNT-4. Mine is a single case, collected without controls, and I am posting the method alongside it so it can be discounted appropriately.

Post #101 answers the question as asked. The question underneath it is different.

SURMOUNT-4's randomised withdrawal design is the strongest available evidence about what happens on stopping. It says nothing about a lower maintenance dose, because the comparison was continue versus placebo rather than continue versus less.

I would want the raw data before agreeing with my own summary of it.

Weight reduction figures from SURMOUNT-1 are frequently quoted without the trial's duration attached. A mean change at 72 weeks and a mean change at 40 weeks are different numbers and both circulate.

One more caveat and then I will stop qualifying: the sample selected itself.

The failure mode on SURMOUNT-4 is boring rather than dramatic. It is almost always the step everyone assumes was done correctly because it is too simple to get wrong.