SURMOUNT-1 — trial digest
SURMOUNT-1 (N Engl J Med 2022): What weight reduction does tirzepatide achieve in obesity?
Citation and design
| Field | Value |
|---|---|
| Trial | SURMOUNT-1 |
| Intervention | Tirzepatide 5, 10 and 15 mg weekly |
| Publication | N Engl J Med, 2022 (first author Jastreboff) |
| Design | Double-blind, placebo-controlled, 72 weeks |
| Population | Adults with obesity or overweight with a weight-related complication, without diabetes |
This digest summarises the trial and the criticisms our journal club considered material. It is not a substitute for the paper, and where the two differ the paper is right.
The question it set out to answer
What weight reduction does tirzepatide achieve in obesity?
Stating the question before the result is a house convention. A great many arguments about this trial are actually arguments about what it was for.
What it found
The pivotal obesity trial for tirzepatide and the largest mean weight reduction reported for a pharmacological intervention at the time of publication.
A clear dose-response across the three doses studied.
The proportion of participants reaching large categorical weight-loss thresholds was the result that attracted most attention.
Criticisms the journal club considered material
- As with STEP 1, the estimand determines the headline number and the two versions differ.
- Categorical thresholds are easy to communicate and can exaggerate an impression of separation between arms.
- 72 weeks, in a chronic condition, with an enrolled population narrower than the interested population.
These are criticisms of the design and of how the result is used, not of the investigators. Sessions that lose that distinction get moderated.
How it is misused
The two recurring misuses of this trial in general discussion are quoting the relative effect without the absolute one, and extending the result to a population the trial did not enrol. Both are easy to correct and both keep happening.
Where a number appears in secondary coverage without an estimand attached, assume it is whichever version is larger and check the paper.
Maintenance
Digests are reviewed when new analyses of the same trial are published, and at the review date shown above regardless. If a secondary publication changes the picture, raise it in journal club rather than editing the digest directly, so the change is discussed before it lands.
Revision history
| 2026-07-15 | forest_plot | Split an overlong section in two and gave the second a proper heading. |
| 2026-05-24 | DSakamoto | Removed a paragraph that duplicated a linked page, and linked it instead. |
| 2026-03-04 | w.novak | Updated a dated claim and added the date explicitly, per the maintenance convention. |
| 2025-11-15 | v.szabo | Corrected a unit label in the second table — it read mg where it should have read mg/mL. |
| 2025-10-09 | Birkeland | Citation sweep: two references did not support the sentences attached to them and have been replaced. |
| 2025-08-05 | o.lindgren | Added cross-references to the two topics that most often ask this question. |
| 2025-05-03 | bench_notes | Initial promotion from the source topic. Structure taken from the marked solution. |
Every edit to a maintained document records its author and a note explaining the change. An edit without a note may be reverted by any wiki editor under R9, and the revert is logged. Disagreements about content belong on the source topic rather than in the revision history (R10).
Related documents
- STEP 1 — trial digestSTEP 1 (N Engl J Med 2021): Does semaglutide 2.4 mg weekly reduce body weight in adults with obesity and no diabetes?
- STEP 2 — trial digestSTEP 2 (Lancet 2021): What weight reduction does semaglutide 2.4 mg achieve in people who also have type 2 diabetes?
- STEP 3 — trial digestSTEP 3 (JAMA 2021): What does semaglutide add on top of intensive behavioural therapy?
- STEP 4 — trial digestSTEP 4 (JAMA 2021): What happens if you stop after reaching the maintenance dose?
- STEP 8 — trial digestSTEP 8 (JAMA 2022): How does weekly semaglutide compare directly with daily liraglutide?