The FOURIER (Further Cardiovascular Outcomes Research with PCSK9 inhibition in Subjects with Elevated Risk) trial included many cardiovascular events that might be unrelated to atherosclerosis.

The adaptive design allowed an intermediate increase in the targeted sample size, which resulted in a faster accrual of events and therefore the possibility of shortening the follow-up.

The rate of all-cause mortality was growing for evolocumab versus placebo after 2 years of follow-up.

The originally planned follow-up of FOURIER would have yielded the necessary evidence about this potential safety issue with evolocumab.