Self-confidence in clinical skills may or may not correlated with actual clinical competency level. In case that they are not correlated, could self-confidence still have an impact on patient outcomes?.
In my opinion (without having done studies), self-confidence in and of itself would, at best, serve as an *amplifier* of results based on the provider's underlying skill. In other words, self-confidence in a skilled surgeon might allow better outcomes because the provider can make correct decisions faster, while self-confidence in an unskilled surgeon would lead to bigger and badder errors/outcomes because the (falsely) confident surgeon could forge ahead, ignoring all the danger signs and advice to the contrary.
An open question in my mind is to the extent self-confidence in a skilled practitioner would lead the practitioner to fail to properly assess information that challenges the self-confidence. For example, would a confident surgeon be insensitive to and tend to mentally discount problems with a patient's vital signs during surgery (since s/he *knows* that the surgery is being performed well), leading to a failure to appreciate and respond to a problem? Of course, self-confidence is not necessarily incompatible with the humility needed to practice as a Master Adaptive Learner, constantly alert to questions and focused on opportunities to improve . . . I must say, however, that many self-described "self-confident" individuals have been the sort to limit their receptivity to differing points of view, leading to a less-than-ideal problem resolution. (As to the latter point, see extensive research on decision-making summarized in "In Defense of Troublemakers: The Power of Dissent in Life and Business")