Looks like medical records data.

I love the smell of healthcare data in the morning. Smells like ... KAAAACCCHHHIIIIINNNNNGGGGG!!!! 😀

Seriously though, you should be able to find out who is running it, or at least the app name, with some easy extra columns on the sp_whoisactive or similar DMV queries.

Capture the query plan. I would be willing to bet there is at least one mismatched data type in there and a big scan or few. I am severely whipsawed on timezones right now, but IIRC that wait type is related to chewing on lots of data?

Bet you have the default settings still for Cost Threshold for Parallelism and MAXDOP too ...