Who took part

SELECT enrolled 17,604 adults aged 45 or over with established cardiovascular disease, a BMI of at least 27 kg/m² and no diabetes. Participants took weekly semaglutide or placebo alongside usual care. The primary endpoint combined cardiovascular death, non-fatal heart attack and non-fatal stroke. These were people at higher risk. The trial did not sample everyone who wants to lose weight.

The primary finding

A primary endpoint event happened in 6.5% of the semaglutide group and 8.0% of the placebo group. The hazard ratio was 0.80, usually reported as a 20% relative reduction in the event hazard. The plain difference between the two event percentages is 1.5 percentage points. Relative and absolute measures describe the same result in different ways. Give both together.

How the 20% figure gets misread

The result does not mean 20 in every 100 treated people avoided an event. Nor did each person's risk fall by 20 percentage points. The benefit depends on your starting risk and the time period. Someone with a different cardiovascular history may have a different absolute chance of benefit. Do not turn the trial headline into a personal prediction without a clinician's input.

Reading a composite endpoint

Combining several events gives a trial enough data to answer its question more reliably. Every component did not necessarily improve by the same amount or with the same certainty. When a headline claims the medicine prevents one particular event, check the analysis for that component. The primary composite result does not prove every cardiovascular outcome improved.

What SELECT means for UK prescribing

The current Wegovy injection information includes cardiovascular risk reduction in a defined population. The licensed indication, an NHS funding decision and your own suitability each need checking. SELECT does not mean everyone with a raised BMI qualifies for NHS semaglutide. The trial also did not show the same cardiovascular result for every GLP-1 product or for oral forms.

Semaglutide adds to usual care

The trial tested treatment on top of standard care. Semaglutide did not replace other heart medicines or follow-up. Do not stop a statin, blood pressure medicine or antiplatelet because you have started semaglutide. A useful consultation covers your whole prevention plan, possible side effects and the likely absolute benefit. SELECT shows why judging GLP-1 medicines takes more than a weight-loss league table.

Absolute differences depend on time

People often turn the event-rate difference into a number needed to treat and quote the figure without context. That number depends on follow-up length, the population's risk and the statistical method. A benefit measured over several years says nothing about one month. For a personal decision, ask your clinician to explain the likely absolute benefit over a relevant period, alongside the burden of treatment and side effects. The trial supports an informed discussion. It offers no lifetime guarantee.

Sources

Your own medicine leaflet and prescriber come first. A source from another country does not mean the same rule applies in the UK.

  1. SELECT: original trial publication nejm.org
  2. Wegovy injection: UK prescribing information medicines.org.uk

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