ICD10CM, often spelled “ICD-10-CM”, is a coding system in the USA, which is based on the WHO ICD10 coding system, but contains a large number of additions and extensions:
Note: ICD10CM is often simply referred to as “ICD-10” in the literature, creating confusion with the WHO ICD10. Many of the codes are equivalent, but because of the modifications and additions it is a vocabulary in its own right in the OMOP Standardized Vocabularies. For a discussion of the WHO ICD10 please visit here.
The procedures for transforming Concepts from the source to the OMOP Standard Vocabularies can be found here.
All Concepts are assigned the longest of all available names.
All ICD10CM codes are represented in the format containing the dot.
All ICD10CM codes are non-Standard.
ICD10CM Concept Classes identify each Concept as part of the general coding scheme of diagnoses and disorders, classified into 21 Chapters (not explicitely identified in the OMOP Standardized Vocabularies). In addition, the Concept Classes distinguish between billing and non-billing codes. These are defined according to the Health Care Services Coding System of the Centers of Medicare and Medicaid Services (CMS). Billing codes are those that are designated for reimbursement of services, while higher level codes are non-billing.
|3-char nonbill code|
|3-char billing code|
|4-char nonbill code|
|4-char billing code|
|5-char nonbill code|
|5-char billing code|
|6-char nonbill code|
|6-char billing code|
|7-char billing code||There are no 7-character non-billing codes|
For each ICD10CM Concept, the Domain is inferred from the SNOMED Concept it is mapped to. If a ICD10CM Source Concept is mapped to more than one target SNOMED Concept, a combination Domain is assigned. If a ICD10CM Concept has no mappings the Domain is inferred from it's neighboring codes.
|Condition||Bulk of ICD9CM codes|
|Condition/Meas||Only deprecated legacy codes|
There are only mapping relationships defined for ICD10CM.
ICD10CM concepts are non-Standard Concepts and therefore are mapped to Standard Concepts through records in the CONCEPT_RELATIONSHIP table. All such mappings point to SNOMED-based concepts. Most of these SNOMED Concepts are in the Condition Domain, but despite the fact that ICD10CM is a “Classification of Disease” some of them get mapped to Procedure, Measurement and Observation Domain Concepts. All mappings are manually maintained by a team of curators.
Most mappings establish one-to-one equivalence between the Concepts. However, some ICD10CM Concepts are pre-coordinated (consist of several semantic components), contain negations, declarations about conditions at an unspecified time in the past (e.g. medical history of), declarations about people other than the patient (e.g. family history), lab test findings, mixed mother/child conditions or Observations. All these cases are properly handled as described in the Mapping description.
All ICD10CM concepts are non-Standard. That means, they have to be mapped to the corresponding Standard Concepts using the CONCEPT_RELATIONSHIP table (“Maps to” and occasionally “Maps to value” records). Most of them map to single Condition Concepts, generating one-to-one records in the CONDITION_OCCURRENCE table, but some of them create multiple records or mappings to other domains.
ICD10CM Concepts are non-Standard Concepts and therefore do not participate in the hierarchy of the CONCEPT_ANCESTOR table.