There has been much hyperbole since the presentation of results from the SELECT cardiovascular outcomes trial (CVOT) at this year’s European Congress on Obesity, which led many to herald semaglutide as the “new statin.”
In the SELECT CVOT, participants with overweight or obesity (body mass index [BMI] ≥ 27), established cardiovascular disease (CVD), and no history of type 2 diabetes were administered the injectable glucagon-like peptide 1 (GLP-1) receptor agonist semaglutide (Wegovy) at a 2.4-mg dose weekly. Treatment resulted in a significant 20% relative risk reduction in major adverse CV events (a composite endpoint comprising CV death, nonfatal myocardial infarction, or nonfatal stroke). Importantly, SELECT was a trial on secondary prevention of CVD.
The CV benefits of semaglutide were notably independent of baseline weight or amount of weight lost. This suggests that the underlying driver of improved CV outcomes with semaglutide extends beyond simple reduction in obesity and perhaps indicates a direct effect on vasculature and reduction in atherosclerosis, although this remains unproven.
Not All Risk Reduction Is Equal
Much of the sensationalist coverage in the lay press focused on the 20% relative risk reduction figure. This endpoint is often more impressive and headline-grabbing than the absolute risk reduction, which provides a clearer view of a treatment’s real-world impact.
In SELECT, the absolute risk reduction was 1.5 percentage points, which translated into a number needed to treat (NNT) of 67 over 34 months to prevent one primary outcome of a major adverse CV event.
Lower NNTs suggest more effective treatments because fewer people need to be treated to prevent one clinical event, such as the major adverse CV events used in SELECT.
Semaglutide vs Statins
How does the clinical effectiveness observed in the SELECT trial compare with that observed in statin trials when it comes to the secondary prevention of CVD?
The seminal 4S study published in 1994 explored the impact of simvastatin on all-cause mortality among people with previous myocardial infarction or angina and hyperlipidemia (mean baseline BMI, 26). After 5.4 years of follow-up, the trial was stopped early owing to a 3.3-percentage point absolute risk reduction in all-cause mortality (NNT, 30; relative risk reduction, 28%). The NNT to prevent one death from CV causes was 31, and the NNT to prevent one major coronary event was lower, at 15.
Other statin secondary prevention trials, such as the LIPID and MIRACL studies, demonstrated similarly low NNTs.
So, you can see that the NNTs for statins in secondary prevention are much lower than with semaglutide in SELECT. Furthermore, the benefits of semaglutide in preventing CVD in people living with overweight/obesity have yet to be elucidated.
In contrast, we already have published evidence showing the benefits of statins in the primary prevention of CVD, albeit with higher and more variable NNTs than in the statin secondary prevention studies.
The benefits of statins are also postulated to extend beyond their impact on lowering low-density lipoprotein cholesterol. Statins have been suggested to have anti-inflammatory and plaque-stabilizing effects, among other pleiotropic benefits.
We also currently lack evidence for the cost-effectiveness of semaglutide for CV risk reduction. Assessing economic viability and use in health care systems, such as the UK’s National Health Service, involves comparing the cost of semaglutide against the health care savings from prevented CV events. Health economic studies are vital to determine whether the benefits justify the expense. In contrast, the cost-effectiveness of statins is well established, particularly for high-risk individuals.