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What did the placebo arm of TRIUMPH-1 report for constipation?

Asked 21 Nov 2025Modified 7 months agoViewed 6.4k times
12

What I have: TRIUMPH-1 · constipation.

I can parse the result. I am less sure what it licenses me to conclude.

I have deliberately not looked at anyone else’s interpretation yet.

Which parts of this are informative and which are decoration?

clinical-trials
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askedper_haugen13k1721 Nov 2025

4 Answers

Accepted answer first, then by votes
102

Accepted answer

The TRIUMPH-1 placebo arm is the only thing that makes its treatment arm interpretable, and it is the row nobody quotes. Symptoms reported under placebo in these programmes are not rare, because the population is being asked about them weekly and would have had some of them regardless. The attributable figure is the treated rate minus the placebo rate, and that difference is routinely a fraction of the headline. Two cautions on the subtraction: the arms must have been assessed the same way, and a discontinuation for an event removes that participant from later time points in both arms, which flatters whichever arm loses more people.

Answer first: read the primary endpoint, the comparator and the population before you read the effect size. Almost every argument on this site about a trial is really an argument about one of those three.

Duration decides what can be seen. A 68-week trial can measure weight and glycaemia; it cannot measure anything whose event rate is one per cent per year without enrolling tens of thousands.

Relative to absolute, worked

QuantityValueDerivation
Control-arm event rate8.0 %From the trial table, not the abstract
Hazard ratio0.80Reported
Treated event rate6.4 %8.0 × 0.80
Absolute risk reduction1.6 pp8.0 − 6.4
Number needed to treat631 ÷ 0.016
Relative risk reduction20 %1 − 0.80

The last two rows describe the same finding. Only one of them is used in headlines.

On the detail: non-inferiority and superiority designs are not interchangeable. A non-inferiority result says the new agent is not meaningfully worse against a pre-specified margin — it does not say it is as good, and it certainly does not say it is better.

Registry entries at ClinicalTrials.gov carry the pre-specified primary endpoint with a timestamp, which is the cheapest available check on whether an endpoint was changed after the data were seen.

Read the protocol and the statistical analysis plan if the result matters to you. Both are usually published alongside.

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answered · acceptedDr_Colm_Fitzhenry69k24715 Dec 2025
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41

More usefully, a trial establishes what happened to a defined group under a defined protocol. Extending it beyond that group is inference, and inference is allowed as long as it is labelled.

Intention-to-treat and per-protocol analyses answer different questions. ITT asks what happens if you offer the treatment; per-protocol asks what happens if it is taken as directed. The gap between the two is a measure of how tolerable the protocol was.

Concretely, placebo arms in this class are not nothing. Lifestyle-intervention placebo arms in the major obesity trials commonly lose two to three per cent of body weight, so an active-arm figure quoted without its comparator overstates the drug effect by roughly that much.

Where a result is quoted from a conference abstract rather than a peer-reviewed publication, the numbers routinely move between the two. It is worth checking which one you are reading.

The caveat is that trial evidence is about licensed product administered under supervision. None of it transfers automatically to research-grade material of unverified content.

If a claim cannot be traced to a named trial with a named endpoint, treat it as a claim rather than as evidence.

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answeredivo_paunovic16k273 Dec 2025
31

The honest answer here is that the published evidence supports part of the claim and is silent on the rest, and it is worth being precise about which part is which.

Confidence intervals matter more than point estimates when two trials disagree. Two studies reporting fifteen and twenty per cent whose intervals overlap heavily have not disagreed about anything.

On the detail: a composite endpoint is only as informative as its least serious component. Where a cardiovascular composite combines death, infarction and stroke, ask which component moved, because they are not interchangeable outcomes.

One qualification: absence of a signal in a trial of this size is not evidence of absence for a rare event. It is evidence that the event is rarer than the trial could detect.

The short version: check the endpoint, check the comparator, check who was excluded, then look at the number.

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DS
answeredDr_Hanne_Solberg36k276 Jan 2026
2Is the open-label extension included in that figure, or just the randomised phase? – grainne_ahearn 8 months ago
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26

Look at the discontinuation rate alongside the efficacy figure. A large effect in the two thirds who stayed is a different result from a large effect in everyone.

Trial populations are selected. Exclusion criteria in this class routinely remove people with significant renal impairment, prior pancreatitis and unstable psychiatric illness, which is exactly the population the results are then quoted for.

Be careful about generalising from a trial population to yourself. The exclusion criteria are usually the most informative page in the supplement.

When two sources disagree, the answer is almost always in the methods section of the one you have not read.

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answeredtenth_of_a_unit57k3726 Dec 2025
3Thank you for separating the surrogate from the outcome. That distinction gets lost constantly. – aine_mulcahy 4 months ago
2Adding a vote because this deserves more of them. – Dr_Rosalind_Achebe 3 months ago
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Your answer

Ask PeptideStack is a static archive. Posting is closed, but the norms are worth stating: answer the question that was asked, show your working, cite the trial or the certificate, and say plainly where the evidence runs out.

Not medical advice. Research-use-only compounds are not approved for human use.