Patients table

Patients table

Information that is consistent for the lifetime of a patient is stored in this table.

Table columns

Name Postgres data type
subject_id INTEGER
gender VARCHAR(1)
anchor_age INTEGER
anchor_year INTEGER
anchor_year_group VARCHAR(255)

Detailed Description


subject_id is a unique identifier which specifies an individual patient. Any rows associated with a single subject_id pertain to the same individual. As subject_id is the primary key for the table, it is unique for each row.


gender is the genotypical sex of the patient.

dod is the date of death as recorded in the hospital database.

anchor_age, anchor_year, anchor_year_group

These columns provide information regarding the actual patient year for the patient admission, and the patient’s age at that time.

  • anchor_year is a shifted year for the patient.
  • anchor_year_group is a range of years - the patient’s anchor_year occurred during this range.
  • anchor_age is the patient’s age in the anchor_year.
  • Example: a patient has an anchor_year of 2153, anchor_year_group of 2008 - 2010, and an anchor_age of 60.
    • The year 2153 for the patient corresponds to 2008, 2009, or 2010.
    • The patient was 60 in the shifted year of 2153, i.e. they were 60 in 2008, 2009, or 2010.
    • A patient admission in 2154 will occur in 2009-2011, an admission in 2155 will occur in 2010-2012, and so on.


ANCHOR_AGE, ANCHOR_YEAR, and ANCHOR_YEAR_SHIFTED are intended to be analyzed together. The ANCHOR_AGE is the age of the patient in the given ANCHOR_YEAR/ANCHOR_YEAR_SHIFTED. In order to determine the age of a patient on admission to the hospital, it is necessary to account for the number of years between ANCHOR_YEAR_SHIFTED and their hospital admission time.


The de-identified date of death for the patient. Date of death is extracted from the hospital information system only, and does not include out of hospital mortality as of MIMIC-IV v1.0.

Last modified August 14, 2020: tidy content a bit more (5b74d84)