People do case control studies all the time, the factors used depend based on disease but there is plenty of literature to support selection of matching factors

People do case control studies all the time, the factors used depend based on disease but there is plenty of literature to support selection of matching factors I think it would make sense to start at the hospital level; provider level probably isn't feasible as you say. Hospitals see enough patients where the sample sizes are pretty big, and they are the main cost driver in healthcare, so rating hospitals by cost / quality could work