The icustays table

Table source: Hospital database.

Table purpose: Defines each ICUSTAY_ID in the database, i.e. defines a single ICU stay.

Number of rows: 61,532

Links to:

• PATIENTS on SUBJECT_ID
• ADMISSIONS on HADM_ID

Important considerations

• ICUSTAY_ID is a generated identifier that is not based on any raw data identifier. The hospital and ICU databases are not intrinsically linked and so do not have any concept of an ICU encounter identifier.
• The ICUSTAYS table is derived from the TRANSFERS table. Specifically, it groups the TRANSFERS table based on ICUSTAY_ID, and excludes rows where no ICUSTAY_ID is present.

Table columns

Name	Postgres data type
ROW_ID	INT
SUBJECT_ID	INT
HADM_ID	INT
ICUSTAY_ID	INT
DBSOURCE	VARCHAR(20)
FIRST_CAREUNIT	VARCHAR(20)
LAST_CAREUNIT	VARCHAR(20)
FIRST_WARDID	SMALLINT
LAST_WARDID	SMALLINT
INTIME	TIMESTAMP(0)
OUTTIME	TIMESTAMP(0)
LOS	DOUBLE

Detailed Description

SUBJECT_ID, HADM_ID, ICUSTAY_ID

Identifiers which specify the patient: SUBJECT_ID is unique to a patient, HADM_ID is unique to a patient hospital stay and ICUSTAY_ID is unique to a patient ICU stay.

DBSOURCE

DBSOURCE contains the original ICU database the data was sourced from. Patients admitted between 2001 - 2008 had their data managed by the CareVue information system, represented in this column as ‘carevue’. Patients admitted between 2008 - 2012 had their data managed by the Metavision system, represented in this column as ‘metavision’. Knowing the database source is important as the data archiving for these two databases differs in some cases.

FIRST_CAREUNIT, LAST_CAREUNIT

FIRST_CAREUNIT and LAST_CAREUNIT contain, respectively, the first and last ICU type in which the patient was cared for. As an ICUSTAY_ID groups all ICU admissions within 24 hours of each other, it is possible for a patient to be transferred from one type of ICU to another and have the same ICUSTAY_ID.

Care units are derived from the TRANSFERS table, and definition for the abbreviations can be found in the documentation for TRANSFERS.

FIRST_WARDID, LAST_WARDID

FIRST_WARDID and LAST_WARDID contain the first and last ICU unit in which the patient stayed. Note the grouping of physical locations in the hospital database is referred to as ward. Though in practice ICUs are not referred to as wards, the hospital database technically tracks ICUs as “wards with an ICU cost center”. As a result, each ICU is associated with a WARDID.

INTIME, OUTTIME

INTIME provides the date and time the patient was transferred into the ICU. OUTTIME provides the date and time the patient was transferred out of the ICU.

LOS

LOS is the length of stay for the patient for the given ICU stay, which may include one or more ICU units. The length of stay is measured in fractional days.