OMOP/Documentation/CommonDataModel_Wiki_Files/StandardizedClinicalDataTables/VISIT_DETAIL.md

The VISIT_DETAIL table is an optional table used to represents details of each record in the parent visit_occurrence table. For every record in visit_occurrence table there may be 0 or more records in the visit_detail table with a 1:n relationship where n may be 0. The visit_detail table is structurally very similar to visit_occurrence table and belongs to the similar domain as the visit.

Field	Required	Type	Description
visit_detail_id	Yes	integer	A unique identifier for each Person's visit or encounter at a healthcare provider.
person_id	Yes	integer	A foreign key identifier to the Person for whom the visit is recorded. The demographic details of that Person are stored in the PERSON table.
visit_detail_concept_id	Yes	integer	A foreign key that refers to a visit Concept identifier in the Standardized Vocabularies belonging to the 'Visit' Vocabulary.
visit_detail_start_date	No	date	The start date of the visit.
visit_detail_start_datetime	Yes	datetime	The date and time of the visit started.
visit_detail_end_date	No	date	The end date of the visit. If this is a one-day visit the end date should match the start date.
visit_detail_end_datetime	Yes	datetime	The date and time of the visit end.
visit_detail_type_concept_id	Yes	Integer	A foreign key to the predefined Concept identifier in the Standardized Vocabularies reflecting the type of source data from which the visit record is derived belonging to the 'Visit Type' vocabulary.
provider_id	No	integer	A foreign key to the provider in the provider table who was associated with the visit.
care_site_id	No	integer	A foreign key to the care site in the care site table that was visited.
visit_detail_source_value	No	string(50)	The source code for the visit as it appears in the source data.
visit_detail_source_concept_id	Yes	Integer	A foreign key to a Concept that refers to the code used in the source.
admitted_from_source_value	No	Varchar(50)	The source code for the admitting source as it appears in the source data.
admitted_from_concept_id	Yes	Integer	A foreign key to the predefined concept in the 'Place of Service' Vocabulary reflecting the admitting source for a visit.
discharge_to_source_value	No	Varchar(50)	The source code for the discharge disposition as it appears in the source data.
discharge_to_concept_id	Yes	Integer	A foreign key to the predefined concept in the 'Place of Service' Vocabulary reflecting the discharge disposition for a visit.
preceding_visit_detail_id	No	Integer	A foreign key to the VISIT_DETAIL table of the visit immediately preceding this visit
visit_detail_parent_id	No	Integer	A foreign key to the VISIT_DETAIL table record to represent the immediate parent visit-detail record.
visit_occurrence_id	Yes	Integer	A foreign key that refers to the record in the VISIT_OCCURRENCE table. This is a required field, because for every visit_detail is a child of visit_occurrence and cannot exist without a corresponding parent record in visit_occurrence.

Conventions

All conventions used in VISIT_OCCURRENCE apply to VISIT_DETAIL, with some notable exceptions as detailed below

No.	Convention Description
1	A Visit Detail is an optional detail record for each Visit Occurrence to a healthcare facility. For every record in VISIT_DETAIL there has to be a parent VISIT_OCCURRENCE record.
2	One record in VISIT_DETAIL can only have one VISIT_OCCURRENCE parent.
3	A single VISIT_OCCURRENCE record may have many child VISIT_DETAIL records.
4	Valid Visit Concepts belong to the 'Visit' domain. Standard Visit Concepts are yet to be defined, but will represent a detail of the Standard Visit Concept in VISIT_OCCURRENCE.
5	Handling of death: In the case when a patient died during admission (VISIT_DETAIL.DISCHARGE_TO_CONCEPT_ID = 4216643 'Patient died'), a record in the Observation table should be created with OBSERVATION_TYPE_CONCEPT_ID = 44818516 (EHR discharge status 'Expired').
6	Source Concepts from place of service vocabularies are mapped into these Standard Visit Concepts in the Standardized Vocabularies.
7	On any one day, there could be more than one visit. VISIT_OCCURRENCE allows for more than one visit within a single day. VISIT_DETAIL is to be used to only capture details within the visit.
8	One visit may involve multiple Providers, in which case, in VISIT_OCCURRENCE, the ETL must specify how a single PROVIDER_ID is selected or leave the PROVIDER_ID field null. VISIT_DETAIL allows for the ETL to specify multiple child records per VISIT_OCCURRENCE - and each of these child records may represent different PROVIDER_IDs.
9	One visit may involve multiple Care Sites, in which case, in VISIT_OCCURRENCE, the ETL must specify how a single CARE_SITE_ID is selected or leave the CARE_SITE_ID field null. VISIT_DETAIL allows for the ETL to specify multiple child records per visit occurrence - and each of these child records may represent different CARE_SITEs.
10	Just like in VISIT_OCCURRENCE, records in VISIT_DETAIL may be sequentially related to each. These sequential relations are represented using PRECEDING_VISIT_DETAIL_ID.
11	Unlike VISIT_OCCURRENCE, VISIT_DETAIL may have nested visits with hierarchical relationships to each other. These relationships are represented using VISIT_DETAIL_PARENT_ID.
12	In US claims data Header/summary data that summarizes the entire claim and Line/detail that details a claim, detail is thus a child of the summary, and for every record in summary there is one or more records in detail. i.e. there will be at least one foreign key link from VISIT_DETAIL to VISIT_OCCURRENCE.

For example: an entire inpatient stay maybe one record in the VISIT_OCCURRENCE table. This may have one or more detail records such as ER, ICU, medical floor, rehabilitation floor etc. Each of these visit details may have different start/end date-times, different concept_ids and fact_ids. These would become separate records in VISIT_DETAIL with a FK link to VISIT_OCCURRENCE.

Each record within VISIT_DETAIL may be related to each other, sequentially –> ER leading to ICU leading to medical floor, leading to rehabilitation, or in hierarchical parent-child visit –> a visit for dialysis while in ICU.

Note the domain is Visit, and it is shared between VISIT_OCCURRENCE and VISIT_DETAIL in OMOP CDM. The key deviation from VISIT_OCCURRENCE is

• self-referencing key: a new foreign key visit_detail_parent_id allows self referencing for nested visits.
• VISIT_DETAIL points to its parent record in the VISIT_OCCURRENCE table (visit_occurrence_id)