Effects of report cards on referral patterns to cardiac surgeons.

Patients' choices of specialist physicians may be guided by referring physicians and report cards. I examine referral patterns to cardiac surgeons to assess whether publication of the May 2002 edition of Pennsylvania's Guide to Coronary Artery Bypass Graft Surgery added information to what referring physicians already knew. To do so, I developed a counterfactual scenario, including a simulated analogue report card, based on comparable data from Florida, a state without CABG report cards. My analysis failed to detect a significant change in referral patterns to either low-mortality or high-mortality cardiac surgeons. At the same time, referring physicians on average appear to have been knowledgeable about the relative performance of cardiac surgeons without report cards. Future report card efforts might benefit from incorporating the quality signals contained in referral patterns.