to keep the conversation going:
Here is possible representation of trial enrollment using OBSERVATION table.
entering a trial - Enrollement (start)
Observation_concept_id: http://www.ohdsi.org/web/atlas/#/concept/4163733 (Patient consented to clinical trial)
leaving the trial early (due to a decision of a patient (no longer interested) or researcher (non compliance) (end)
Observation_concept_id:http://www.ohdsi.org/web/atlas/#/concept/4087907 (Patient withdrawn from trial)
fully completing the trial (end)
Observation_concept_id: http://www.ohdsi.org/web/atlas/#/concept/40482840 Completion of clinical trial