Accepted answer
Read the 2 mg row, not the pooled one. A programme that randomised more than one dose level reports each arm separately, and the figure that circulates afterwards is usually either the top-dose arm or an average across arms nobody was randomised to. If SELECT ran a 2 mg arm, that row carries its own sample size and its own confidence interval, and both are narrower than the trial-level ones by roughly the square root of however many arms there were. Take the primary publication rather than the press release: one reports by arm, the other reports whichever number is largest. A dose level inside a trial is a protocol decision made under supervision, not a recommendation, and nothing here is medical advice.
Answer first: read the primary endpoint, the comparator and the population before you read the effect size. Almost every argument on this site about a trial is really an argument about one of those three.
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.
Relative to absolute, worked
| Quantity | Value | Derivation |
|---|
| Control-arm event rate | 8.0 % | From the trial table, not the abstract |
| Hazard ratio | 0.80 | Reported |
| Treated event rate | 6.4 % | 8.0 × 0.80 |
| Absolute risk reduction | 1.6 pp | 8.0 − 6.4 |
| Number needed to treat | 63 | 1 ÷ 0.016 |
| Relative risk reduction | 20 % | 1 − 0.80 |
The last two rows describe the same finding. Only one of them is used in headlines.
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.
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.