CDM Table name: observation_period

Reading from ukb_gp.gp_registrations, ukb_gp.gp_clinical, ukb_gp.gp_scripts, ukb_gp.death

Records in gp_registrations, gp_clinical, and gp_scripts with invalid event dates (‘1901-01-01’, ‘1902-02-02’, ‘1903-03-03’, ‘1909-09-09’, ‘2037-07-07’) are excluded. These records are removed during data curation, prior to the ETL process.

Destination Field	Source field	Logic	Comment field
observation_period_id			Autogenerate
person_id	eid
observation_period_start_date	gp_registrations.reg_date gp_clinical.event_dt gp_scripts.issue_date	LEAST(reg_date, MIN(event_dt), MIN(issue_date))	Please note that not all participants with primary care data available have a corresponding registration record. Therefore, gp_clinical.event_dt, gp_scripts.issue_date are also taken into consideration.
observation_period_end_date	death.date_of_death gp_clinical.event_dt gp_scripts.issue_date	COALESCE(LEAST(death_date, GREATEST(MAX(event_dt), MAX(issue_date)), date of datacut)
period_type_concept_id		32880 - Standard algorithm