These graphs display risk adjusted mortality data in the form of funnel plots. The operations included in these charts are adult cardiac surgery operations on all patients over the age of 18, excluding heart transplants, insertion of artificial mechanical hearts, emergencies and trauma cases.
The funnel plots show how risk adjusted mortality rates of a particular surgeon compare to the national average, which is the standard that has been set for outcomes. The risk adjusted mortality rates of surgeons are plotted on the chart against the number of procedures undertaken. Each surgeon is represented by one dot on the funnel. The dot is the risk adjusted mortality, which means that each dot has been adjusted using complex methods so that effectively they show what the mortality would have been had each surgeon operated on the average case mix.
To adjust for differing risk profiles between patients, an adaptation of the EuroSCORE risk adjustment model has been used for these analyses, and whilst it is known that the model is an accurate predictor overall, and discriminates well in general between patients with higher and lower risk, it is also known that it is not designed to adjust for surgeons or hospitals with very unusual case mix profiles, and great caution should be taken in making judgments in this context.