I have the full paper rather than the abstract, and the supplementary appendix.
I understand the observation; what I do not understand is the mechanism behind it.
I have read the two review articles that come up first and both assert this without a citation to a primary source.
Can someone derive this rather than assert it?
Because two papers on PIONEER-4 are usually reporting two different estimands from the same randomisation. The treatment-policy estimand asks what happened to everyone assigned, including those who stopped; the trial-product estimand asks what happens if you keep taking it. The second is always the larger number, and both are legitimate answers to different questions. Then there is the analysis population — randomised, treated, or completers — and the handling of missing data, where a last-observation-carried-forward and a multiple imputation can differ by a point or more. Neither paper is wrong. Read the statistical methods section and you will find both figures defined in it.
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.
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.
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.
When two sources disagree, the answer is almost always in the methods section of the one you have not read.
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 sampleFounded 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 BiochemLook 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.
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.
Specifically, 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.
Meta-analyses in this area are dominated by whichever trial contributed the most participants, so read the forest plot rather than the summary estimate.
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.
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.
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.
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.
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.
edited 5 Jun 2024 by coring_risk — added the placebo-arm figures
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.
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 short version: check the endpoint, check the comparator, check who was excluded, then look at the number.
This is answerable from the published record, but only if you take the placebo arm seriously rather than reading the active arm alone.
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.
Read the protocol and the statistical analysis plan if the result matters to you. Both are usually published alongside.
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.