Surgeons at Hospital a Report That the Mortality Rate at the End

Multiple Choice

Surgeons at Hospital A report that the mortality rate at the end of a one-year follow-up after a new coronary bypass procedure is 15%. At Hospital B, the surgeons report a one-year mortality rate of 8% for the same procedure. Before concluding that the surgeons at Hospital B have vastly superior skill, which of the following possible confounders would you examine?

A) The severity (stage) of disease of the patients at the two hospitals at baseline
B) The starting point of the one-year follow-up at both hospitals (after operation versus after discharge)
C) Difference in the postoperative care at the two hospitals
D) Equally thorough follow-up for mortality
E) All are correct.