I could not help but detect a degree of bias in this study against physicians in non-teaching hospitals. Expressions such as "Teaching status may affect patient outcomes directly because of better knowledge and skills" imply a degree of superiority of surgeons in the teaching hospitals, which, until proven otherwise, has no foundation in fact. This is an opinion of the authors, which needs to be qualified or deleted. This biased opinion in favor of the teaching hospitals is further compounded by the comment "one would generally expect surgeons in teaching hospitals to receive more complex cases." Again, this is an opinion which needs to be qualified by fact and may indicate another biased opinion rather than reality.

I agree with the authors that differences in patient outcome between the two types of hospital need to be analyzed. If there is a factor that differentiates care in the non-teaching versus teaching centers that influences patient survival, it needs to be detected and corrected. If differences in outcome are "artifacts of misclassification," this study needs to be expanded to confirm or refute this point and a correction offered. In the meantime, however, let us not fall into the trap of publishing articles such as this, which are biased and have a limited role in the improvement of health care for Canadians. Patients need to have confidence in the care that they are receiving regardless of whether they choose to obtain care in a teaching or a non-teaching institution.