Patients’ Online Physician Ratings and Quality of Care for coronary artery bypass graft (CABG) surgery concludes there is no correlation between patients’ online rating and risk-adjusted mortality rates. Median number of reviews per doctor was only 4. Study based on 590 surgeons performing CABG surgery in 5 large states. Article by Okike, Peter-Gibb et al, published in the Journal of Medical Internet Research, Dec. 13, 2016. See the abstract and full free text at this link, through PubMed