Quantifying the interaction between angiotensin-converting enzyme inhibitors and aspirin: Are we using the right method?

Angiotensin-converting enzyme (ACE) inhibitors reduce mortality in patients with heart failure and coronary artery disease. Recently, there has been g rowing concern about the possible interaction between ACE inhibitors and as pirin. Numerous investigators have addressed this issue; however, results a re equivocal. Most researchers used a statistical test of interaction, but the use of this method has been criticized. To assess the interaction betwe en ACE inhibitors and aspirin properly, an additive model-more specifically , the Rothman Synergy Index-should be used. Further investigation with this model, however, is needed.