Do major cardiovascular outcomes in patients with stable ischemic heart disease in the clinical outcomes utilizing revascularization and aggressive drug evaluation trial differ by healthcare system?

BACKGROUND: The Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation (COURAGE) trial enrolled patients from 3 distinct healthcare systems (HCSs) in North America. The primary aim of this study was to determine whether there is a treatment difference in cardiovascular outcomes by HCS. METHODS AND
RESULTS: The study population included 968 patients from the US Department of Veterans Affairs (VA), 386 from the US non-VA, and 931 from Canada with different comorbidities and prognoses. The primary outcome was all-cause mortality or nonfatal myocardial infarction (MI) during the median 4.6-year follow-up. Baseline demographics were similar between percutaneous coronary intervention and optimal medical therapy treatment groups within each HCS. After follow-up, the primary end point of total mortality and nonfatal MI was not statistically significant between percutaneous coronary intervention and optimal medical therapy, regardless of HCS: VA, 22.3% versus 21.9% (hazard ratio, 1.05; 95% CI, 0.80-1.38; P=0.95); US non-VA, 15.8% versus 21.8% (hazard ratio, 0.70; 95% CI, 0.43-1.12; P=0.24); Canadian HCS, 17.3% versus 13.5% (hazard ratio, 1.30; 95% CI, 0.93-1.83; P=0.17). The interaction between HCSs and treatment was not statistically significant. Long-term mortality was significantly higher in the VA system as a result of significantly greater comorbidity and worse left ventricular function.
CONCLUSIONS: In the COURAGE trial, addition of percutaneous coronary intervention to optimal medical therapy did not improve 5-year survival or reduce MI or other major adverse cardiovascular events regardless of whether patients were Canadian or American or US veterans or non-veterans. Outcome differences were largely explained by differences in baseline characteristics known to affect long-term prognosis.