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documentation:cdm:measurement [2014/12/06 16:46] cgreich |
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===== MEASUREMENT table ===== | ===== MEASUREMENT table ===== | ||
- | A Measurement is a structured value (numerical or categorical) obtained through systematic and standardized examination or testing of a Person or Person's sample. The Measurement table contains measurement contains both orders and results of such Measurements as laboratory tests, vital signs, quantitative findings from pathology reports, etc. | + | The MEASUREMENT table contains records of Measurement, i.e. structured values (numerical or categorical) obtained through systematic and standardized examination or testing of a Person or Person's sample. The MEASUREMENT table contains both orders and results of such Measurements as laboratory tests, vital signs, quantitative findings from pathology reports, etc. |
^Field^Required^Type^Description^ | ^Field^Required^Type^Description^ | ||
|measurement_id|Yes|integer|A unique identifier for each Measurement.| | |measurement_id|Yes|integer|A unique identifier for each Measurement.| | ||
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|measurement_concept_id|Yes|integer|A foreign key to the standard measurement concept identifier in the Standardized Vocabularies.| | |measurement_concept_id|Yes|integer|A foreign key to the standard measurement concept identifier in the Standardized Vocabularies.| | ||
|measurement_date|Yes|date|The date of the Measurement.| | |measurement_date|Yes|date|The date of the Measurement.| | ||
- | |measurement_time|No|time|The time of the Measurement.| | + | |measurement_time|No|time|The time of the Measurement. (Some database systems don't have a datatype of time. To accomodate all temporal analyses, datatype datetime can be used (combining measurement_date and measurement_time)[[http://forums.ohdsi.org/t/date-time-and-datetime-problem-and-the-world-of-hours-and-1day/314|Relevant Forum Discussion]]| |
|measurement_type_concept_id|Yes|integer|A foreign key to the predefined Concept in the Standardized Vocabularies reflecting the provenance from where the Measurement record was recorded.| | |measurement_type_concept_id|Yes|integer|A foreign key to the predefined Concept in the Standardized Vocabularies reflecting the provenance from where the Measurement record was recorded.| | ||
|operator_concept_id|No|integer|A foreign key identifier to the predefined Concept in the Standardized Vocabularies reflecting the mathematical operator that is applied to the value_as_number. Operators are <, ≤, =, ≥, >.| | |operator_concept_id|No|integer|A foreign key identifier to the predefined Concept in the Standardized Vocabularies reflecting the mathematical operator that is applied to the value_as_number. Operators are <, ≤, =, ≥, >.| | ||
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* Measurements differ from Observations in that they require a standardized test or some other activity to generate a quantitative or qualitative result. For example, LOINC 1755-8 concept_id 3027035 'Albumin [Mass/time] in 24 hour Urine' is the lab test to measure a certain chemical in a urine sample. | * Measurements differ from Observations in that they require a standardized test or some other activity to generate a quantitative or qualitative result. For example, LOINC 1755-8 concept_id 3027035 'Albumin [Mass/time] in 24 hour Urine' is the lab test to measure a certain chemical in a urine sample. | ||
* Even though each Measurement requires to have a result, the fields value_as_number and value_as_concept_id are not mandatory. When the result is missing, the Measurement record might represent an order or the result was not captured in the source data (missing data). | * Even though each Measurement requires to have a result, the fields value_as_number and value_as_concept_id are not mandatory. When the result is missing, the Measurement record might represent an order or the result was not captured in the source data (missing data). | ||
- | * Valid Measurement Concepts (measurement_concept_id) belong to the 'Measurement' domain, but could overlap with the 'Observation' domain. This is due to the fact that there is a continuum between systematic examination or testing (Measurement) and a simple determination of fact (Observation). | + | * Valid Measurement Concepts (measurement_concept_id) belong to the 'Measurement' domain, but could overlap with the 'Observation' domain. This is due to the fact that there is a continuum between systematic examination or testing (Measurement) and a simple determination of fact (Observation). When the Measurement Source Value of the code cannot be translated into a standard Measurement Concept ID, a Measurement entry is stored with only the corresponding source_concept_id and measurement_source_value and a measurement_concept_id of 0. |
* 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). | * 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. | * Valid Concepts for the value_as_concept field belong to the 'Meas Value' domain. |