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What does SURPASS-3 report at the 5 mg dose level?

Asked 20 Mar 2024Modified 2.0 years agoViewed 54k times
20

Stated plainly: SURPASS-3 · 5 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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askedhana_petrikova10k1420 Mar 2024

5 Answers

Accepted answer first, then by votes
97

Accepted answer

Read the 5 mg row, not the pooled one. A programme that randomised more than one dose level reports each arm separately, and the figure that circulates afterwards is usually either the top-dose arm or an average across arms nobody was randomised to. If SURPASS-3 ran a 5 mg arm, that row carries its own sample size and its own confidence interval, and both are narrower than the trial-level ones by roughly the square root of however many arms there were. Take the primary publication rather than the press release: one reports by arm, the other reports whichever number is largest. A dose level inside a trial is a protocol decision made under supervision, not a recommendation, and nothing here is medical advice.

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

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.

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.

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.

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

edited 26 Jun 2024 by Dr_Jonas_Halvorsen — added the citation requested in comments

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DH
answered · acceptedDr_Jonas_Halvorsen28k3710 Jun 2024
4Adding a vote because this deserves more of them. – Dr_Malik_Osei 2 months ago
5This should be linked from the help pages. – fib4_reader 3 months ago
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37

Concretely, 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.

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.

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.

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

edited 26 Jun 2024 by t_oyelaran — clarified the distinction between purity and content

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TO
answeredt_oyelaran79k4821 Jun 2024
The placebo-arm figure is the part everyone omits. – deamidation_watch 9 months ago
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30

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.

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.

Mechanically, 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.

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

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DB
answeredDr_Aoife_Brennan20k272 Jul 2024
24

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.

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.

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.

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

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DA
answeredDr_Yusuf_Adeyemi54k14713 Jul 2024
17

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.

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.

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.

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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VR
answeredv_ramaswamy68k5726 Mar 2024
4This matches what I was told by a clinician, for whatever that is worth. – noor_alhassan 6 months ago
5Do you have a reference for the last claim? Not disputing it, just want to read it. – lipid_panel_q 7 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.