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What does STEP 1 tell me about vomiting at the 2 mg dose?

Asked 25 Dec 2024Modified 15 months agoViewed 33k times
This question was closed as primarily opinion-based.Closed 31 Dec 2024. Answers already posted are preserved; new answers are not accepted. Questions here need a factual basis on which they can be answered.
22

Stated plainly: STEP 1 · vomiting · 2 mg.

I would like help reading this properly rather than being told what conclusion to reach.

I have the full report including the method section, so I can quote specifics if that helps.

What would I need in addition before this supported a decision?

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askedelke_brunner17k2825 Dec 2024

5 Answers

Accepted answer first, then by votes
13

Accepted answer

Only what the 2 mg arm reported, and the denominator is that arm rather than the trial. Adverse-event tables are published per arm, so the 2 mg incidence of vomiting has its own numerator and its own denominator, and pooling it with the other arms produces a figure that describes nobody. Two further deductions before you use it. Subtract the placebo arm — vomiting occurs in people who received nothing, and the difference is the part attributable to the drug. And check whether STEP 1 counted events or counted participants: one participant with six episodes is one row in a participant count and six in an event count, and the two get quoted interchangeably. Nothing here is medical advice.

The short version: the effect is real, the magnitude depends on the population, and the population is usually the part that gets dropped when a result is quoted second-hand.

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.

Headline results, principal programmes

TrialAgentnDurationPrimary result
STEP 1Semaglutide 2.4 mg1,96168 wk−14.9 % vs −2.4 % weight
STEP 2Semaglutide 2.4 mg, T2DM1,21068 wk−9.6 % vs −3.4 % weight
SURMOUNT-1Tirzepatide 5/10/15 mg2,53972 wk−15 / −19 / −21 % weight
SURMOUNT-4Tirzepatide, withdrawal67088 wkContinued loss vs substantial regain
SELECTSemaglutide 2.4 mg17,604~40 moMACE HR 0.80 (0.72–0.90)
FLOWSemaglutide 1.0 mg, CKD3,533~3.4 yrRenal composite reduced; stopped early
SURMOUNT-OSATirzepatide, OSA46952 wkAHI reduced with and without PAP

Put another way, 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.

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.

I am not a clinician and this is not medical advice; it is a reading of a published protocol.

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

edited 13 Mar 2025 by esther_vandeVelde — updated for the 2026 guidance change

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EV
answered · acceptedesther_vandeVelde52k274 Mar 2025
2The exclusion criteria are the most informative page in the supplement and nobody reads them. – m_haraldsen 5 months ago
Do you have a reference for the last claim? Not disputing it, just want to read it. – gunnar_isaksen 4 months ago
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32

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.

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.

In practice, 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.

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.

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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DV
answeredDr_Bram_Verhoeven84k24818 Apr 2025
5

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.

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.

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.

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.

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

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DV
answeredDr_Ilse_Vandenberg113k24827 Mar 2025
3

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.

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.

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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LD
answeredloss_on_drying40k13816 Mar 2025
2Is the open-label extension included in that figure, or just the randomised phase? – sian_llewellyn 10 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.

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.

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

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

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DO
answeredDr_Lena_Ostrowska38k277 Apr 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.