CDM Table name: observation_period (CDM v5.4)

Reading from hesin, death

Destination Field	Source field	Logic	Comment field
observation_period_id			Autogenerate
person_id	eid
observation_period_start_date	admidate, epistart, disdate, epiend	Use all four fields in case some of them are null	use the earliest of (admidate,epistart,disdate,epiend) that is not null.
observation_period_end_date	death.date_of_death, disdate, epiend, admidate, epistart	Use all four fields in case some of them are null	use the latest of (disdate, epiend, admidate, epistart) that is not null, then the earliest between that and death.date_of_death.
period_type_concept_id		32880 - Standard algorithm