What is the probability that coronary artery surgery prolongs life?

Two-hundred and nine male patients who had coronary artery surgery from 1972 to 1974 at the Marshfield Clinic (MC) were compared with Veterans Administration (VA) coronary patients to determine the probability of coronary surgery prolonging life. The survival data includes operative and late cardiac and noncardiac deaths. Including the MC operative mortality rates but considering late noncardiac deaths withdrawn as alive at the time of death, the MC cumulative 5-year surgical survival rate is 93%. This is identical to predicted 93% 5-year survival rate for any man of 54.5 years, the average age of MC patients living in this geographic locale in 1973. Annual attrition rates, including the noncardiac deaths, are 1.4% for any man 1.5% per year for MC patients, based on MC 5-year survival data. It is probable that coronary surgery prolongs life by sharply reducing late cardiac deaths.