This is basically the question that Perez and Freedman (2018) ask. They find the following:
Among crowdsourcing sites’ best‐ranked hospitals, 50–60% were also the best ranked on [Hospital Compare’s] HC’s overall and patient experience ratings; 20% ranked as the worst. Best‐ranked hospitals had significantly better clinical quality scores than worst ranked hospitals, but were not more likely to be the highest rated in terms of HC’s clinical quality measures alone…Crowdsourcing sites and HC provide comparable information on patient experience; scores were less consistent in terms of risk‐adjusted measures of patient safety and clinical quality.
Read the whole article here.