PeptideStack
5.2kquestions
20kanswers
220users

Why do two papers on SOUL report different headline figures?

Asked 28 Oct 2025Modified 6 months agoViewed 25k times
26

I have the full paper rather than the abstract, and the supplementary appendix.

I can predict the outcome but I cannot explain it, which means I will get the next case wrong.

I would like to know how confident the field actually is about this.

What is actually going on here, physically?

clinical-trials
clinical-trials

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

745 questions
dosing-math
dosing-math

The arithmetic itself: milligrams to millilitres to insulin units, concentration after reconstitution, dose per draw, and vial-days per vial. Show…

764 questions
semaglutide
semaglutide

A GLP-1 receptor agonist with a fatty-acid-acylated backbone and a roughly one-week half-life, marketed for type 2 diabetes and for weight…

470 questions
shareeditfollowflag
MH
askedm_haraldsen21k2728 Oct 2025

5 Answers

Accepted answer first, then by votes
33

Accepted answer

Specifically, 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.

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.

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.

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

shareimprove this answerflag
TU
answered · acceptedtenth_of_a_unit57k3716 Nov 2025
8Good answer, but the confidence interval in the cited trial is wider than implied. – m_haraldsen 2 months ago
add a comment
Sponsored

Janoshik Analytical - Independent Third-Party Testing

HPLC purity, identity confirmation and quantified content on the vial you actually hold. Reports arrive with the chromatogram attached, not just a number.

Submit a sample
Sponsored — paired listing

GL Biochem (Shanghai) Ltd. - Direct Synthesis

Founded 1998. ISO 9001 and cGMP certified, 1,500+ staff and 200+ patents. The synthesis house behind a great many of the vials that get sent out for testing - batch-specific documentation with every order.

Visit GL Biochem
13

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.

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.

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

shareimprove this answerflag
PH
answeredpetra_hovland35k385 Nov 2025
3Thank you for separating the surrogate from the outcome. That distinction gets lost constantly. – nine_point_nine 5 months ago
2The placebo-arm figure is the part everyone omits. – ayo_fadipe 3 months ago
add a comment
10

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.

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.

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.

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

shareimprove this answerflag
SK
answereds_kalniete57k388 Dec 2025
9

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.

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.

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.

shareimprove this answerflag
TN
answeredtabular_nums71k4827 Nov 2025
2Which population was that figure from? It moves a lot between the trials. – thermal_mass 2 months ago
Worth flagging that this changed with the 2025 publication, so older answers are out of date. – Dr_Priya_Raghunathan 16 days ago
add a comment
8

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.

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.

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

edited 8 Feb 2026 by lipid_panel_q — tightened the wording; no substantive change

shareimprove this answerflag
LQ
answeredlipid_panel_q36k12730 Jan 2026
5Adding a vote because this deserves more of them. – tandem_gradient 3 months ago
add a comment

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.