Does aspirin attenuate the beneficial effect of ACE inhibitors in elderly people with heart failure?

BACKGROUND: Several studies have raised concerns over a possible reduction in the beneficial effects of ACE inhibitors on mortality in people also taking aspirin (acetylsalicylic acid). OBJECTIVE: We performed this study to determine whether there is a reduction in the beneficial effects of ACE inhibitors on mortality in elderly people with heart failure also taking aspirin. PARTICIPANTS: 822 patients discharged from hospital wards with a diagnosis of heart failure participated in the GIFA (Italian Group of Pharmacoepidemiology in the Elderly) study. MEASUREMENTS: We analysed the characteristics of the participants according to the type of therapy prescribed (no ACE inhibitor/no aspirin, ACE inhibitor/no aspirin, no ACE inhibitor/aspirin and ACE inhibitor/aspirin). We calculated the hazard ratios (HRs) for dying associated with each of these treatments, and calculated the synergy index to identify any negative interaction between ACE inhibitor and aspirin. Results: The mean age of study participants was 79 +/- 7.3 (SD) years. Of the 629 (76.5%) patients discharged on ACE inhibitor and/or aspirin therapy, 31.0% were taking both drugs. Compared with no therapy with ACE inhibitor or aspirin, the HR for death was 0.65 (95% CI 0.31, 1.36) for aspirin users, 0.45 (95% CI 0.27, 0.74) for ACE inhibitor users and 0.37 (95% CI 0.19, 0.70) for ACE inhibitor/aspirin users. The synergy index was 0.98 (95% CI 0.34, 2.80), suggesting no interaction between the drugs. CONCLUSIONS: Our data do not support the existence of a negative interaction between ACE inhibitors and aspirin in elderly patients with heart failure.