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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?

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MH
askedm_haraldsen38k3828 Oct 2025

5 Answers

Accepted answer first, then by votes
33

Accepted answer

Specifically, start with the population. The inclusion criteria of the trial determine what its result can be extrapolated to, and the extrapolation people want is usually to a population the trial excluded.

Creatinine is a muscle-derived metabolite, so a substantial loss of lean mass lowers serum creatinine and mathematically raises estimated GFR without anything happening to the kidney. If you have lost twenty kilograms, your creatinine-based eGFR is flattering you. Cystatin C is not muscle-dependent and is the measure to use when the two disagree.

Estimated average glucose from HbA1c: eAG in mg/dL = 28.7 × A1c − 46.7, or in mmol/L, 1.59 × A1c − 2.59. An A1c of 6.5 per cent is therefore about 140 mg/dL or 7.8 mmol/L. The relationship is a population regression, so an individual can sit well off the line.

SELECT reported a hazard ratio of 0.80 (95% CI 0.72–0.90) for the primary composite major adverse cardiovascular event endpoint with semaglutide 2.4 mg in overweight or obese adults with established cardiovascular disease and without diabetes[1].

None of this replaces a clinician who can see the whole picture, and the whole picture is usually where the answer is.

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RC
answered · acceptedRP_C1885k15816 Nov 2025
8Adding for future readers: the certificate should carry the lot number, not just a batch code. – m_haraldsen 2 months ago
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13

A single laboratory value is a point on a noisy curve. What you want is a trend across at least three draws under comparable conditions, and "comparable" is doing a lot of work in that sentence.

Absolute risk reduction, worked: if the control-arm event rate is 8.0 per cent over the follow-up period and the hazard ratio is 0.80, the treated rate is approximately 6.4 per cent, the absolute risk reduction is 1.6 percentage points, and the number needed to treat is 1 ÷ 0.016 ≈ 63 over that period. A 20 per cent relative reduction and a number needed to treat of 63 are the same finding stated two ways, and only one of them sounds impressive.

The early fall in estimated glomerular filtration rate on treatment is haemodynamic rather than structural. Reduced intraglomerular pressure lowers the filtration rate acutely and preserves the glomerulus chronically — the same pattern seen with renin-angiotensin blockade and with SGLT2 inhibition. A dip of a few millilitres per minute in the first weeks, followed by a shallower long-term slope, is the desired trajectory, not a warning sign.

If the trend across three draws is flat, the difference between draws one and two was noise. Most of what people react to is noise.

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PH
answeredpetra_hovland42k385 Nov 2025
3Confirming from the other direction: I did the wrong thing and got exactly the predicted outcome. – nine_point_nine 5 months ago
2Is there a reason to prefer the second method over the first, other than cost? – ayo_fadipe 3 months ago
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10

The hazard ratio is the relative effect. What changes decisions is the absolute effect, and converting between them requires the event rate in the control arm, which is usually in the same table and rarely in the abstract.

The rodent thyroid C-cell findings that generated the labelled warning appear to be species-specific: rodent C-cells express GLP-1 receptors at high density, human C-cells at very low density, and human calcitonin data across large trial populations has not reproduced the signal. A family history of medullary thyroid carcinoma or MEN2 is nonetheless a genuine contraindication rather than a theoretical one.

ApoB and LDL-C disagree because they measure different things: LDL-C is the cholesterol mass carried in the LDL fraction, ApoB is a count of atherogenic particles. Small dense particles carry less cholesterol each, so a person with many small particles has a concordantly higher ApoB than their LDL-C suggests. When they disagree, ApoB is the better risk marker.

The papers are readable. Read the paper rather than the summary of the paper, especially where the summary is enthusiastic.

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SK
answereds_kalniete47k388 Dec 2025
9

This is a question about what the trial was designed to answer, and the honest response is that it was not designed to answer this.

HbA1c is a weighted average, not a flat one: roughly half the signal comes from the most recent month. That is why a value drawn six weeks after a change already reflects most of the effect, and why a value drawn during rapid haematological turnover reflects something other than glycaemia.

FLOW tested a composite renal endpoint — kidney failure, sustained 50 per cent eGFR decline, or renal or cardiovascular death — in type 2 diabetes with chronic kidney disease, and was stopped early for efficacy[1].

Worth being explicit that this is interpretation of published data and not medical advice. Laboratory results belong in a conversation with whoever ordered them.

Convert everything to an absolute effect before you compare two interventions. Relative effects are not comparable across different baseline risks.

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HP
answeredh_pergande86k25827 Nov 2025
2Small correction: the units in the third paragraph should be micrograms, not milligrams. – thermal_mass 2 months ago
Do you have a reference for the last claim? Not disputing it, just want to read it. – Dr_Priya_Raghunathan 16 days ago
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8

Read the estimand before the effect size. Almost every apparent contradiction between two published figures from the same trial resolves once you notice that one is a trial-product estimand and the other is a treatment-policy estimand.

Liver enzymes are a poor surrogate for hepatic histology in both directions: substantial steatohepatitis with normal transaminases is common, and modest enzyme elevation with minimal fibrosis is common. If the question is fibrosis, the answer comes from a non-invasive score such as FIB-4 or a stiffness measurement, not from ALT.

Read the confidence interval, read the estimand, and compute the absolute effect yourself. It takes two minutes and it changes how the result feels.

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

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answeredlipid_panel_q44k13830 Jan 2026
5The placebo-arm figure is the part everyone omits. – tandem_gradient 3 months ago
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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.

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