Handling of admission-discharge transfers (ADT) to CDM

• Requester: OMOP-PCORnet Interoperability Collaborative (c/o Rimma Belenkaya)
• Discussion: link to forum post.

Proposal

Relevant table: VISIT_OCCURRENCE

Presently, admission source and discharge disposition are stored in the Observation table and
linked to Visit_Occurrence table via visit_occurrence_id. There is no explicit connection between
two linked visits, the connection is derived by visit start and end date.

• Move attributes representing admitting source and discharge disposition to Visit_Occurence table as first class attributes. This change will eliminate the need to join Visit_Occurrence and Observation tables to link visit and visit attributes. It will also simplify ETL from the source by targeting only one table rather than splitting attributes related to a visit to two tables.
• Represent transition of care by two explicitly linked visits (e.g. from emergency room to inpatient admission). This addition will provide an unambiguous link between two connected visits.

Add the following admitting source fields to VISIT_OCCURRENCE table:

Add the following discharge disposition fields to VISIT_OCCURRENCE table:

In addition to the “Place of Service” vocabulary, the following SNOMED concepts for discharge disposition can be used:

• Patient died: 4216643
• Absent without leave: 44814693
• Patient self-discharge against medical advice: 4021968

Conventions for handling death in hospital

• In case when patient died during admission (Visit_Occurrence. discharge_disposition_concept_id = 4216643 ‘Patient died’), a record in the Death table should be created with death_type_concept_id = 44818516 (“EHR discharge status "Expired").

Convention for linking connected visits:

• Add a field indicating a visit immediately preceding the current visit to Visit_Occurrence table:

An example is below:

Convention for representing linked emergency room – inpatient admission visits

• Some EMR systems combine emergency room followed by inpatient admission into one visit, and it is close to impossible to separate the two. To annotate this visit type, add a new visit concept “Emergency Room and Inpatient Visit”.

Use Cases

• Analysis of continuity of care
• Key clinical outcomes - e.g. risk factors for being transferred ED to IP, SX to ICU, etc.
• Readmission analysis, readmission inclusion and exclusion criteria

Importance, also with respect to other projects

• This change is an important enhancement to the model and can be implemented immediately without impacting other projects.
• This change will have an immediate affect on three OMOP-based CDRNs: NYC-CDRN representing over 2.5 million patients; pSCANNER covering over 21 million patients; and PEDSnet which includes eight of the nation's largest children's hospitals and provides service to 4.6 million children per year.

Consequences

• This change will enhance representation and analysis of transition of care in OMOP CDM and simplify ETL for the sites that are presently using Observation table.
• It will have no implications on vocabulary or existing software.