---
type: source
title: "Semaglutide Reduces MACE Independent of Baseline Adiposity and Weight Loss: SELECT Trial Prespecified Analysis"
author: "John Deanfield et al. (SELECT investigators)"
url: https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(25)01375-3/fulltext
date: 2025-11-01
domain: health
secondary_domains: []
format: journal-article
status: unprocessed
priority: high
tags: [GLP-1, semaglutide, SELECT-trial, cardiovascular, weight-independent, mechanism, adiposity, MACE]
---

## Content

**Prespecified analysis of the SELECT trial** (semaglutide 2.4mg weekly vs. placebo, N=17,604, adults ≥45 with BMI ≥27, pre-existing CVD, no diabetes at baseline). Published in The Lancet, November 2025.

**Study question:** Does semaglutide's cardiovascular benefit vary by baseline adiposity level or degree of weight loss achieved?

**Key findings:**
- Semaglutide reduced MACE (cardiovascular death, non-fatal MI, non-fatal stroke) consistently across **ALL baseline categories** of body weight and waist circumference
- **No evidence of treatment heterogeneity** by baseline adiposity — people with lower BMI benefited as much as those with higher BMI
- **"No evidence that the treatment effect of semaglutide was mediated by time-varying weight loss"** — the benefit is not weight-loss dependent
- Approximately **33% of MACE reduction** explained by early reductions in waist circumference
- The remaining **~67% of MACE benefit** is independent of adiposity/weight change
- The study was led by John Deanfield and colleagues; published November 2025 in The Lancet

**Complementary finding (ESC 2024 mediation analysis, Colhoun/Lincoff):**
- Body weight mediates: 19.5% of CV benefit
- hsCRP (inflammation): 42.1%
- Joint mediation of all measured factors: 31.4% (wide 95% CI: -30.1% to 143.6%)
- ~68.6% of benefit is pleiotropic/unexplained by measured metabolic or adiposity parameters

**The two analyses converge on the same conclusion:** approximately 67-69% of semaglutide's CV benefit is independent of weight or adiposity changes. Anti-inflammatory pathways (hsCRP) are the largest single measured mediator.

## Agent Notes

**Why this matters:** Closes the active thread from Session 14 (ESC 2024 mediation analysis). The Lancet 2025 prespecified analysis is stronger evidence than the ESC abstract — it's a prespecified, not exploratory, analysis. The weight-independence finding has major implications for (1) who should receive the drug (not just high-BMI patients), (2) why access barriers are so consequential (blocking a drug that works via anti-inflammatory/SDOH-generated mechanisms, not just weight), and (3) the claim that GLP-1s represent a pharmacological antidote to structurally-generated inflammatory CVD risk.

**What surprised me:** The magnitude. I expected modest weight-independence — perhaps 30-40%. Finding that ~67-69% of benefit is adiposity-independent suggests GLP-1 agonists are fundamentally anti-inflammatory agents that happen to also cause weight loss, not weight-loss agents that happen to reduce CVD risk. This flips the therapeutic framing.

**What I expected but didn't find:** Evidence that benefit was concentrated in patients achieving significant weight loss. The flat treatment effect across weight-change categories is the opposite of that expectation.

**KB connections:**
- [[GLP-1 receptor agonists are the largest therapeutic category launch in pharmaceutical history but their chronic use model makes the net cost impact inflationary through 2035]] — SELECT 2025 analysis suggests the CV mechanism is anti-inflammatory, not weight-mediated; changes the mechanistic framing
- [[medical care explains only 10-20 percent of health outcomes because behavioral social and genetic factors dominate as four independent methodologies confirm]] — GLP-1 working through SDOH-generated inflammatory pathways is an interesting intersection: medicine reaching into non-clinical risk terrain

**Extraction hints:**
- Extractable as a standalone claim: "Semaglutide's cardiovascular benefit in SELECT is approximately 67-69% independent of weight or adiposity change, with anti-inflammatory pathways (hsCRP) accounting for more of the benefit than weight loss"
- Could be a second claim: "GLP-1 agonists function primarily as anti-inflammatory cardiovascular drugs rather than weight-loss drugs that incidentally reduce CV risk, based on SELECT mediation analyses"

**Context:** SELECT trial (2023 primary results, NEJM) was the pivotal study showing semaglutide reduced MACE by 20% in non-diabetic obese adults with pre-existing CVD. The 2025 Lancet prespecified analysis is the definitive analysis of the mechanism behind that benefit. Deanfield is a UK cardiologist at UCL; Lincoff (co-author on ESC 2024 analysis) is from Cleveland Clinic.

## Curator Notes (structured handoff for extractor)
PRIMARY CONNECTION: [[GLP-1 receptor agonists are the largest therapeutic category launch in pharmaceutical history but their chronic use model makes the net cost impact inflationary through 2035]]
WHY ARCHIVED: Closes active thread on GLP-1 CV mechanism; establishes weight-independence as the primary clinical finding; connects GLP-1 benefit to SDOH-generated inflammatory pathways
EXTRACTION HINT: Focus on the 67-69% weight-independence figure and the hsCRP mediation (42.1%) — together these establish the anti-inflammatory mechanism. Extract as mechanism claim, not just efficacy claim. Consider whether this should be a divergence with the existing GLP-1 claim that frames the drug primarily through metabolic/weight-loss lens.
