Corraini P, Olsen M, Pedersen L, Dekkers OM, Vandenbroucke JP, Clin Epidemiol. 2017;9:331–338.
On pages 333–334, the interaction contrast appeared incorrectly as 1.5 per 1,000 person-years, where it should read −1.5 per 1,000 person-years. This occurred from an inversion between the result of the rate reduction of heart disease due to aspirin among those receiving warfarin (10.3–8.7=1.6) and the result of the rate reduction due to aspirin among those not receiving warfarin (13.3–10.2=3.1).
The interpretation of the interaction contrast should then read in page 334 as: “As the interaction contrast was below zero, it could be concluded that the effect of combining warfarin and aspirin in reducing ischemic heart disease was lower than that expected by the sum of the effects of either agent on its own.”
This corrigendum had no consequences for the educational message of our paper.