Condition Occurrence

Conditions are records of a Person suggesting the presence of a disease or medical condition stated as a diagnosis, a sign or a symptom, which is either observed by a Provider or reported by the patient. Conditions are recorded in different sources and levels of standardization, for example:

• Diagnoses
• Patient self-reported conditions
• EHR collected problem lists

Note that the diagnosis table is not a cohort list. It is simply the recorded states of the patient. Creation of Cohorts, e.g. all patients who have or might have COVID-19, is done using the COHORT table. This is created during processing rather than being submitted by the sites.

Field	Required	Type	FK Table	Description
condition_occurrence_id	Yes	bigint		A unique identifier for each Condition Occurrence event.
person_id	Yes	bigint	PERSON	A foreign key identifier to the Person who is experiencing the condition. The demographic details of that Person are stored in the PERSON table.
condition_concept_id	Yes	bigint	CONCEPT	A foreign key that refers to the Concept identifier representing the condition.
condition_start_date	Yes	date		Use this date to determine the start date of the condition.
condition_start_datetime	No	datetime		If a source does not specify datetime the convention is to set the time to midnight (00:00:0000).
condition_end_date	No	date		Use this date to determine the end date of the condition.
condition_end_datetime	No	datetime		If a source does not specify datetime the convention is to set the time to midnight (00:00:0000).
condition_type_concept_id	Yes	bigint	CONCEPT	The Concept that represents the type of diagnosis this is (.e.g billing, self-reported, problem list). See Condition Type below.
condition_status_concept_id	No	bigint	CONCEPT	The status of the diagnosis. See Condition Status below.
stop_reason	No	varchar(20)		Not used.
provider_id	No	bigint	PROVIDER	Not used.
visit_occurrence_id	No	bigint	VISIT_OCCURRENCE	A foreign key to the Visit Occurrence record during which the Condition was determined (diagnosed).
visit_detail_id	No	bigint	VISIT_DETAIL	The VISIT_DETAIL record during which the condition occurred. For example, if the Person was in the ICU at the time of the diagnosis the VISIT_OCCURRENCE record would reflect the overall hospital stay, and the VISIT_DETAIL record would reflect the ICU stay during the hospital visit.
condition_source_value	No	varchar(50)		Value from the source data representing the condition that occurred. For example, this could be an ICD10 or Read code.
condition_source_concept_id	No	bigint	CONCEPT	If the condition_source_value is coded in the source data using an OMOP supported vocabulary put the concept id representing the source value here.
condition_status_source_value	No	varchar(50)		The field is meant to contain a value indicating when and how a diagnosis was given to a patient. This source value is mapped to a standard concept which is stored in the condition_status_concept_id field.

Conventions

• Valid Condition Concepts belong to the “Condition” domain.
• Condition records are typically inferred from diagnostic codes recorded in the source data. Such code systems like ICD-10, SNOMED, etc., provide a comprehensive coverage of conditions. However, if the diagnostic code in the source does not define a Condition, but rather an Observation or a Procedure, then such information is not stored in the CONDITION_OCCURRENCE table, but in the respective tables instead.
• Most often data sources do not have the idea of a start date for a condition. Rather, if a source only has one date associated with a condition record it is acceptable to use that date for both the condition_start_date and the condition_end_date .

Standard Mappings

Condition Type

Code	Name	Description and scope
32019	EHR Billing diagnosis	ICD10 coded diagnoses, usually at the Consultant Episode level but possibly at visit level, completed by clinical coders after a patient has been discharged
42894222	EHR Chief complaint	Presenting complaints from the Emergency Care Data Set (ECDS)
32020	EHR Encounter diagnosis	Visit-level diagnoses associated with outpatient appointments, A&E attendances or inpatient admissions, if not billing diagnoses.
40301556	Past medical history	Past conditions entered into the patient record which could be chronic but are not being added as the subject of treatment during the current period of care. This Condition Type may not be used by all sites as in some cases past medical history might largely be represented as part of the problem list.
38000245	EHR problem list entry	An EHR problem list contains diagnoses that can be added or removed to a patients electronic record during or as a result of any secondary care activity. The entries persist from one visit to the next (unless they have been ended).

Condition Status

Code	Name
4203942	Admitting diagnosis - used for Encounter diagnoses where appropriate.
44786628	First Position Condition - used for Billing diagnoses and other Encounter diagnoses where appropriate.
4033240	Preliminary diagnosis.
4230359	Final diagnosis (also used for discharge diagnosis).