THIS IS OUTDATED. All documentation is now on the github wiki. Please refer there or to the CDM working group for more information
The CONCEPT_ANCESTOR table is designed to simplify observational analysis by providing the complete hierarchical relationships between Concepts. Only direct parent-child relationships between Concepts are stored in the CONCEPT_RELATIONSHIP table. To determine higher level ancestry connections, all individual direct relationships would have to be navigated at analysis time. The CONCEPT_ANCESTOR table includes records for all parent-child relationships, as well as grandparent-grandchild relationships and those of any other level of lineage. Using the CONCEPT_ANCESTOR table allows for querying for all descendants of a hierarchical concept. For example, drug ingredients and drug products are all descendants of a drug class ancestor.
This table is entirely derived from the CONCEPT, CONCEPT_RELATIONSHIP and RELATIONSHIP tables.
|ancestor_concept_id||Yes||integer||A foreign key to the concept in the concept table for the higher-level concept that forms the ancestor in the relationship.|
|descendant_concept_id||Yes||integer||A foreign key to the concept in the concept table for the lower-level concept that forms the descendant in the relationship.|
|min_levels_of_separation||Yes||integer||The minimum separation in number of levels of hierarchy between ancestor and descendant concepts. This is an attribute that is used to simplify hierarchic analysis.|
|max_levels_of_separation||Yes||integer||The maximum separation in number of levels of hierarchy between ancestor and descendant concepts. This is an attribute that is used to simplify hierarchic analysis.|
A path between two concepts can be characterized by the sequence of relationships that need to be traversed in order to reach a descendant concept from an ancestor concept.
For example, for concepts
|313217||Atrial fibrillation||321588||Heart disease||3||4|
the shortest path in concept_relationship will be :
313217 Atrial fibrillation Is a 4226399 Fibrillation Is a 44784217 Cardiac arrhythmia Is a 321588 Heart disease
313217 Atrial fibrillation Is a 4068155 Atrial arrhythmia Is a 4248028 Supraventricular arrhythmia Is a 44784217 Cardiac arrhythmia Is a 321588 Heart disease