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What did the placebo arm of SURMOUNT-OSA report for injection-site erythema?

Asked 18 Jun 2024Modified 22 months agoViewed 19k times
2

Stated plainly: SURMOUNT-OSA · injection-site erythema.

I would like to know the limits of what can be inferred from this.

What I am trying to avoid is over-reading a single result, which I have done before.

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

clinical-trials
clinical-trials

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

745 questions
injection-site-reaction
injection-site-reaction

Local reactions: erythema, induration, pruritus and nodules. Their relationship to injection depth, diluent composition, benzyl alcohol…

49 questions
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RP
askedrhian_prydderch23k2718 Jun 2024
6Add whether the comparator was placebo or an active agent. – Dr_Tomas_Kral 8 months ago
5Voting to keep this open — it is more specific than it first looks. – forty_two_c 6 months ago
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5 Answers

Accepted answer first, then by votes
56

Accepted answer

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

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.

It helps to be literal here: 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.

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.

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

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RS
answered · acceptedrota_site36k2722 Aug 2024
Worth flagging that this changed with the 2025 publication, so older answers are out of date. – plate_count_9k 7 months ago
8Adding that the endpoint definition differs between the two trials being compared here. – nine_point_nine 5 months ago
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67

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.

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.

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.

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.

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

edited 20 Sept 2024 by rota_site — fixed an arithmetic slip in the third paragraph

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RS
answeredrota_site36k2713 Sept 2024
5The placebo-arm figure is the part everyone omits. – kwn_analytical 3 months ago
6Which population was that figure from? It moves a lot between the trials. – Dr_Lena_Ostrowska 4 months ago
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43

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.

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.

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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DV
answeredDr_Bram_Verhoeven84k24824 Sept 2024
25

Mechanically, 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.

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

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DV
answeredDr_Ilse_Vandenberg113k2482 Sept 2024
2Do you have a reference for the last claim? Not disputing it, just want to read it. – tess_amankwah 6 months ago
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21

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.

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.

Meta-analyses in this area are dominated by whichever trial contributed the most participants, so read the forest plot rather than the summary estimate.

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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answeredpieter_maas14k1730 Jun 2024
2The exclusion criteria are the most informative page in the supplement and nobody reads them. – Dr_Lena_Ostrowska 6 months ago
Thank you for separating the surrogate from the outcome. That distinction gets lost constantly. – kwn_analytical 5 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.