Earlier quoted context omitted.
Is there evidence of correlation?
The next step would be to bring in death/complication statistics by hospital and ratings by surgeon
The surgeons who take these patients may end up having terrible stats, but be the most skilled if only because their mortality rate is not pushing 100%.
Comparing this statistic the way people compare gas mileage is a disincentive for these surgeons to operate on patients that need help, but are high risk.