Mortality after surgery for acute type A aortic dissection stratified by transfer status, volume status, and reroute status. All-cause mortality is plotted against time after surgery and stratified by whether patients (A) were transferred, (B) had surgery at a high-volume or low-volume hospital, and (C) were rerouted to a high-volume hospital. Numbers of patients at risk are included below each figure. Note that some numbers are not integers due to matched pairs with variable controls. CI, confidence interval; HR, hazard ratio