Types of data in the database

Data within MIMIC were recorded during routine clinical care and not explicitly for the purpose of retrospective data analysis. This is a key point to keep in mind when analyzing the data.

There are two types of data in the database: static data and dynamic data. Static data is recorded once for a given identifier. An example of static data is the DOB column in the PATIENTS table. Each patient has only one date of birth, which does not change over time and is not recorded with an associated timestamp. An example of dynamic data is a patient’s blood pressure, which is periodically measured during a hospital stay.

This distinction between static data and dynamic data is merely a helpful conceptual construct: there is no strict technical distinction between date of birth and heart rate. However, static data tends to not have an associated ITEMID (as there is no need to repeatedly record values for static data), whereas dynamic data have an ITEMID to facilitate efficient storage of repeated measurements.

Static data

SUBJECT_ID

The following is a list of static data available in the database for SUBJECT_ID in the PATIENTS table:

The only static data available for patients are their gender (GENDER), date of birth (DOB) and various dates of death (DOD, DOD_HOSP, DOD_SSN). These columns all occur in the PATIENTS table.

HADM_ID

The following is a list of static data available in the database for HADM_ID in the ADMISSIONS table:

• Admission time
• Discharge time
• Death time
• Admission type

ICUSTAY_ID

The following is a list of static data available in the database for ICUSTAY_ID in the ICUSTAYS table:

• INTIME - Time entered the ICU
• OUTTIME - Time left the ICU
• First care unit
• Last care unit

Hospital acquired data

The following tables were sourced from the hospital database, and contain information recorded in the hospital, but not necessarily during the patient’s ICU stay:

• ADMISSIONS
• CALLOUT
• CPTEVENTS
• DIAGNOSES_ICD
• DRGCODES
• ICUSTAYS
• LABEVENTS
• MICROBIOLOGYEVENTS
• PATIENTS
• PRESCRIPTIONS
• PROCEDURES_ICD
• SERVICES
• TRANSFERS

ICU acquired data

The following tables were sourced from the ICU databases, and contain information only during a patient’s ICU stay:

• DATETIMEEVENTS
• INPUTEVENTS_CV
• INPUTEVENTS_MV
• NOTEEVENTS
• OUTPUTEVENTS
• PROCEDUREEVENTS_MV

Externally acquired data

The DOD_SSN (which also contributes to the DOD column) is acquired from the social security death registry. It contains dates of death up to 90 days in the future for Metavision patients. It contains dates of death up to 4 years in the future for CareVue patients.