OBJECTIVE: The IMPRESS clinical trial randomized patients with congestive heart failure to a daily regimen of either omapatrilat or lisinopril. At 24 weeks, patients randomized to omapatrilat had a significant reduction in the primary endpoint of death, hospitalization, or discontinuation of study drug for worsening heart failure (p = 0.035) and fewer cardiac events (p=0.04). This study sought to determine the economic consequences of the omapatrilat patients' lower event rates. METHODS: Economic outcomes were assessed in terms of hospitalization events and their medical costs. Hospital event information was obtained via serious adverse event forms, and hospital costs were evaluated by assigning each hospitalization a DRG-based average cost for physician and hospital services. Emergency room visits for worsening heart failure were assigned costs equivalent to those at Duke University Medical Center. All costs were expressed in 1998 US dollars. Drug costs were not assessed. RESULTS: Patients in the omapatrilat (n = 289) and lisinopril (n = 284) arms were evenly matched with regard to baseline characteristics: age (both 64 years); NYHA class III or IV heart failure (36% versus 38%); ejection fraction (both 28%). There was no difference between study arms in all-cause mortality. However, there was a trend toward a greater number of all-cause hospitalizations in the lisinopril versus omapatrilat patients (0.275 versus 0.215, p = .07). Differences in cardiac hospitalizations between lisinopril and omapatrilat were significant (0.208 versus 0.145, p = .03). There was a trend toward reduced medical costs at 24 weeks follow-up in omapatrilat-treated patients (US$1930 versus US$2002, p = .09). Considering only cardiac medical costs, this trend toward reduced medical costs became significant (US$1240 versus US$1442, p = .03). CONCLUSIONS: In the first study to compare economic outcomes in congestive heart failure patients treated with omapatrilat and lisinopril, we found fewer hospitalizations and lower medical costs for omapatrilat patients at 24 weeks. Cost Estimation