Yeah, this is a problem we are struggling with. What exactly are Care Sites, and what is the right level you want to set them.
As usual, the use cases will give you the answer: Since this is OHDSI Network research, the exact identity of departments, wards, wings and remote locations of a hospital and their logical relationship to each other (the “Urology Dpt” belongs to the “Surgery Wing” of the “Annex Location” - I am making it up of course) is impenetrable to outsiders. That means, comparing outcomes (e.g. hospital infection rates) in the “Annex Location” to the “Main Location” of the institution with all the departments in each is impossible for folks who have no knowledge of the place. That use case is not addressable in a generic fashion.
The use case that people would like to use Care Sites for are as anonymous entities for things like lines of stratification or propensity model covariates. For example, “How much does the hospital infection rate differ between Care Sites?”, without the precise knowledge which one is your “Urology Dpt”. It is just Care Site #3246. So, pick them with that in mind: What are useful delineations that would be good for stratification and covariates.
The only rule you got is that the granularity in VISIT_OCCURRENCE should be coarser than VISIT_DETAIL, or at least not the other way around. So, “Urology Dpt” would be more likely picked for use in _DETAIL, and “Main Location” in _OCCURRENCE.
Wrt to place_of_service: We are abolishing this for Care Site. Look at the latest CDM V6. It is impossible to assign these Places of Service correctly and unambiguously, and also they really are not a “place” to begin with. Instead, the care setting becomes part of the Visit. The Care Site is only some place you picked to attach a unique ID to according to the above reasoning.
Makes sense? I probably haven’t helped too much.