This touches on a general theme of data provenance, and how that can be captured with meta data. This is generally more important when site comparisons are made, as OHDSI can catalyze.
For instance - while this might not effect CDM data directly - in the administrative data world, different countries have different rules about, for instance, what should be the primary diagnosis for a visit. In the US, it's the admitting diagnosis, in Canada, it's the diagnosis that consumed the most hospital resources.
(So in the US a Hip Fracture case that gets a post op MI would be primary Dx of Hip Fracture, in Canada, Primary Dx of MI).
There may also be opportunities to provide better information as to data element provenance. Is it relevant that a source concept originated as a billing diagnostic code vs. a professionally abstracted diagnostic code - typically yes! I am still digging into the CDM but not clear how that kind of provenance info is captured.
Further downstream, I think there's some interesting opportunities to connect to source data architecture - i.e. how the data is captured in EMR systems. In our current EMR project, we're working with / consuming large numbers of archetypes from OpenEHR
(search, for example, for their laboratory archetype. This offers a glimpse at potential metadata slots in a Lab result, but also potentially a Lab order).
I think the combination of an Open clinical data architecture system, with analytics driven by the Open CDM, is really attractive. Perhaps of some relevance to the metadata discussion.