Stratification by CVD risk equations does not inform the use of aspirin for primary prevention in older adults.

Abstract

Purpose: We aimed to determine whether commonly recommended CVD risk equations would inform a risk-benefit discussion on the role for aspirin as a primary prevention strategy for CVD in older persons. We assessed aspirin's effect on CVD and major haemorrhage on the basis of baseline levels of CVD risk using risk scores pertaining to the older age groups.

Methods: We used a) the Framingham (FRS), b) the Atherosclerotic Cardiovascular Disease (ASCVD), and c) the European SCORE2-OP equations to calculate 10-year predicted CVD risk. Participants were classified into predicted risk tertiles (T): lower (T1), intermediate (T2) and higher (T3) risk. We identified CVD and major haemorrhagic events utilising each risk equation's definition of CVD.

Results: The CVD event rate increased from T1 to T3 using all risk equations. For participants with greatest CVD risk (T3) according to FRS and ASCVD, aspirin versus placebo was associated with a proportional 28% (95% CI: 54 to 95%) and 25% (95% CI: 57 to 97%) reduction in CVD risk respectively. However, there was no significant effect of aspirin for individuals with low (T1) or moderate (T2) risk, nor according to the SCORE2-OP tertiles.Rates of major haemorrhagic events were highest in all T3 groups. Aspirin was associated with a significant increase in bleeding events versus placebo in all T1 groups and FRS and SCORE2-OP T2 groups. The reduction in CVD events in FRS and ASCVD T3 groups was offset by a 32% and 15% increased risk of bleeding respectively.

Conclusion: In older persons with no prior cardiovascular events, current CVD risk scores do not identify any subgroups with overall net clinical benefit from low dose aspirin.