I'm confused.  You mention 'per participant' but your code doesn't reference a ParticipantID.   Does your data have ParticipantID, StudyID, CareDate?    Can you show, say, 10 sample records of the data you have (with duplicates) and the data you want after de-duplicating?   It's not clear to me if you want the output to be one record per StudyID or one record per ParticipantID. ... View more