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What did the placebo arm of SURMOUNT-OSA report for nausea?

Asked 2 Jun 2025Modified 11 months agoViewed 20k times
14

What I am working with: SURMOUNT-OSA · nausea.

This is presented as though it settles something, and I am not convinced it does.

I have two documents that appear to disagree, which is what prompted this.

What does this actually establish, and what does it not?

clinical-trials
clinical-trials

Reading the primary literature properly: estimands, intention-to-treat versus per-protocol, confidence intervals, absolute versus relative…

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nausea
nausea

The dominant tolerability signal in every trial of the class: incidence, timing relative to a dose step, duration, and the distinction between…

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askedassay_blank45k382 Jun 2025

5 Answers

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27

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.

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.

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.

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.

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

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DF
answeredDr_Colm_Fitzhenry69k24719 Aug 2025
4Adding a vote because this deserves more of them. – Dr_Rosalind_Achebe 4 months ago
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4

Start with what the trial was powered for. Everything else in the publication is secondary, exploratory, or a subgroup, and those three words mean three different things.

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.

Worth being precise here: 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.

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

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DA
answeredDr_Rosalind_Achebe69k1475 Jul 2025
Good answer, but the confidence interval in the cited trial is wider than implied. – siobhan_deasy 2 months ago
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3

The trial answers a narrower question than the headline suggests, and the narrowing is where the useful information is.

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.

Stated carefully, open-label extensions are not the same evidence as the randomised phase. Once everyone knows what they are taking, the reported outcomes acquire a bias that no analysis fully removes.

The cardiovascular outcome programme in this class runs to several large randomised trials — LEADER for liraglutide, SUSTAIN-6 and SELECT for semaglutide, REWIND for dulaglutide — and they are the reason the class is discussed as more than a weight intervention.

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

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DO
answeredDr_Lena_Ostrowska38k2724 Jun 2025
Is the open-label extension included in that figure, or just the randomised phase? – tobias_maartens 16 days ago
2Absolute risk reduction rather than relative would make this much more useful. – liam_bracken 2 months ago
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3

More usefully, this is answerable from the published record, but only if you take the placebo arm seriously rather than reading the active arm alone.

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.

Meta-analyses in this area are dominated by whichever trial contributed the most participants, so read the forest plot rather than the summary estimate.

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.

Quote the interval alongside the estimate and half the disagreements on this site would not start.

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EV
answeredesther_vandeVelde52k2717 Jul 2025
3

Before comparing two trials, check whether they share an endpoint definition. Frequently they do not, and the numbers then are not comparable in any sense.

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.

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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answereds_bhattacharya31k3828 Jul 2025

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.