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What does SOUL report at the 25 mg dose level?

Asked 3 Jun 2024Modified 22 months agoViewed 76k times
39

Details up front: SOUL · 25 mg.

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.

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

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askedtenth_of_a_unit57k373 Jun 2024
4Voting to keep this open — it is more specific than it first looks. – linnea_wahlberg 10 months ago
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5 Answers

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27

Read the 25 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 SOUL ran a 25 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.

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.

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.

More usefully, 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.

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.

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

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answeredDr_Otto_Lindqvist72k5827 Aug 2024
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19

To be exact about it, this is answerable from the published record, but only if you take the placebo arm seriously rather than reading the active arm alone.

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.

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.

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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answeredravi_pillai12k1716 Aug 2024
16

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.

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.

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.

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

edited 11 Oct 2024 by sian_llewellyn — added the placebo-arm figures

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answeredsian_llewellyn65k14719 Sept 2024
3The number needed to treat is the framing that finally made this concrete for me. – Dr_Bram_Verhoeven 2 months ago
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13

Stated carefully, 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.

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.

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.

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

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

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DL
answeredDr_Otto_Lindqvist72k588 Sept 2024
Minor: the trial name is hyphenated in the original publication. – tobias_maartens 6 months ago
The placebo-arm figure is the part everyone omits. – k_szabo 4 months ago
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12

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

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.

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

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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answeredpriya_menon13k3514 Jul 2024
3Which population was that figure from? It moves a lot between the trials. – b_delacroix 10 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.