Measurement

The MEASUREMENT table contains records of Measurement, i.e. structured values (numerical or categorical) obtained about a Person or Person’s sample. It contains results of Measurements such as laboratory tests, vital signs, quantitative findings from pathology reports, etc.

Field	Required	Type	FK Table	Description
measurement_id	Yes	bigint		A unique identifier for each Measurement.
person_id	Yes	bigint	PERSON	A foreign key identifier to the Person about whom the measurement was recorded. The demographic details of that Person are stored in the PERSON table.
measurement_concept_id	Yes	bigint	CONCEPT	A foreign key to the standard measurement concept identifier in the Standardized Vocabularies.
measurement_date	Yes	date		The UTC date of the Measurement.
measurement_datetime	No	datetime		The result / EPR entry UTC datetime of the Measurement.
measurement_time	No	varchar(10)		Not used.
measurement_type_concept_id	No	bigint	CONCEPT	Not used.
operator_concept_id	Yes if value_as_number is used	bigint	CONCEPT	A foreign key identifier to the predefined Concept in the Standardized Vocabularies reflecting the mathematical operator that is applied to the value_as_number . See Operator below.
value_as_number	No	numeric/float		A Measurement result where the result is expressed as a numeric value.
value_as_concept_id	No	bigint	CONCEPT	A foreign key to a Measurement result represented as a Concept from the Standardized Vocabularies (e.g., positive/negative, present/absent, low/high, etc.).
unit_concept_id	No	bigint	CONCEPT	A foreign key to a Standard Concept ID of Measurement Units in the Standardized Vocabularies.
range_low	No	numeric/float		The lower limit of the normal range of the Measurement. Assumed to be of the same unit of measure as the Measurement value.
range_high	No	numeric/float		The upper limit of the normal range of the Measurement. Assumed to be of the same unit of measure as the Measurement value.
provider_id	No	bigint	PROVIDER	Not used.
visit_occurrence_id	No	bigint	VISIT_OCCURRENCE	A foreign key to the Visit Occurrence during which the Measurement was recorded.
visit_detail_id	No	bigint	VISIT_DETAIL	A foreign key to the Visit Detail during which the Measurement was recorded.
measurement_source_value	No	varchar(100)		Not used.
measurement_source_concept_id	No	bigint	CONCEPT	Not used.
unit_source_value	No	varchar(100)		Not used.
value_source_value	No	varchar(100)		Not used.
last_updated_datetime	Yes	datetime		Initially this is the time the row was written to OMOP. If the row is subsequently updated, it then becomes the most recent update time.
deleted_datetime	No	datetime		NULL initially. Set to the time when the row was marked for deletion. A value in this column sent to the central data source will result in this row being deleted (by person_id ) from the combined dataset. Deletions only need to be sent once.

Conventions

• Measurements differ from Observations in that their results are either categorical coded values or numbers. Observations are anything else.
• Measurements are stored as attribute-value pairs, with the attribute as the Measurement Concept and the value representing the result. The value can be a Concept (stored in value_as_concept ), or a numerical value (value_as_number ) with a Unit (unit_concept_id ).
• Valid Concepts for the value_as_concept field belong to the “Meas Value” domain.
• If reference ranges for upper and lower limits of normal are provided (typically by a laboratory) these are stored in the range_high and range_low fields. Ranges have the same unit as the value_as_number .
• The Visit during which the Measurement was made is recorded through a reference to the VISIT_OCCURRENCE table. This information is optional.

Standard Mappings

Operator

Code	Name
4171756	<
4171754	<=
4172703	=
4172704	>
4171755	>=