That is a new paper by Susan F. Lu & Huaxia Rui, here is the abstract:
Despite heated debate about the pros and cons of online physician ratings, very little systematic work examines the correlation between physicians’ online ratings and their actual medical performance. Using patients’ ratings of physicians at RateMDs website and the Florida Hospital Discharge data, we investigate whether online ratings reflect physicians’ medical skill by means of a two-stage model that takes into account patients’ ratings-based selection of cardiac surgeons. Estimation results suggest that five-star surgeons perform significantly better and are more likely to be selected by sicker patients than lower-rated surgeons. Our findings suggest that we can trust online physician reviews, at least of cardiac surgeons.