What is the rationale for the lower COR for prophylactic aspirin in the present guideline?
The relative benefits of aspirin, specifically in preventing nonfatal MI and perhaps stroke (with a trend to lower mortality) have been less evident in more recent trials. Meta-regression analyses of historical trials show that observed ASCVD risk tracks reasonably well with baseline-estimated ASCVD risk. In contrast, observed bleeding risk on aspirin is less well correlated with baseline-estimated ASCVD risk. Post hoc study of older trials suggests that the benefit risk ratio for prophylactic aspirin generally becomes more favorable at >10% estimated ASCVD risk. These recent data are the rationale for the lower COR for prophylactic aspirin in the present guideline (Class IIb) and the removal of a specific PCE risk threshold as an inclusion criterion for aspirin consideration.