Vocab. ICD10

ICD Family Vocabularies

ICD10 is a coding system developed by the WHO for disease and mortality reporting.

In some countries, ICD10 is extended by local codes. For example, in the US a derivative system called ICD10CM is in use, in Germany a similar ICD10GM. Even though many of the codes are shared, those country-specific coding systems are separate and distinct vocabularies in their own right in the OMOP Standardized Vocabularies.

ICD10

Sources

• WHO ICD10 Guideline
• Classifications Download Area

Transformation

The procedures for transforming concepts from the source to the OMOP Standard Vocabularies can be found on the OHDSI GitHub in the respective folders.

Concept Names

All Concepts are assigned the longest of all available names.

Concept Code

All ICD10 codes are represented in the format containing the dot.

Standard Concepts

All ICD10 codes are non-Standard which means that they are mapped to the respective Standard concepts defined by the vocabulary team. Technically, they have single (1-to-1) or several (1-to-many) “Maps to” relationships in the concept_relationship_table. Due to the peculiarities of ICD vocabularies names where ‘AND’ actually means ‘OR’, most mappings are pre-coordinated.

Concept Classes

ICD10 has two Concept Classes: “ICD10 code” and “ICD10 Hierarchy”. “ICD10 Hierarchy” Concepts are all highest level 3-character codes. All codes that are subclassifications of them and contain a dot in the code are Concept Class “ICD10 code”.

Domains

Currently, for each ICD10 concept, the domain is inferred from the concept it is mapped to.

The ‘Condition’ domain is assigned to all the codes for malignant tumors (those starting from ‘C’).

Domain	Notes
Condition
Measurement
Observation
Procedure

Concept Relationships

There are mapping relationships defined for ICD10. There are also internal hierarchical ‘Is a’ and reverse ‘Subsumes’ relationships between ICD10 chapters, subchapters, and codes.

Mapping sources:

Most mappings were curated manually. Mapping candidates have been collected from SNOMED to ICD10, SNOMED to ICD10CM equivalence tables, and through UMLS and NCIm. Mapping consistency and reuse within the ICD Family is carried out through Сommon Data Environment (CDE).

ICD10 to Standard map

ICD10 concepts are non-Standard concepts and therefore are mapped to standard concepts through records in the CONCEPT_RELATIONSHIP table. Most of the target standard concepts are in the Condition domain, but despite the fact that ICD10 is a “Classification of Disease” some of them get mapped to Procedure, Measurement, and Observation domain concepts.

Most mappings establish one-to-one equivalence between the concepts. However, some ICD10 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.

Target concept Domain	Number of ICD codes
Condition	15816
Observation	3008
Procedure	272
Measurement	160
Device	78
Meas Value	62

Instructions for ETL

All ICD10 concepts are non-Standard. That means they have to be mapped to the corresponding Standard concepts using the CONCEPT_RELATIONSHIP table (“Maps to” and “Maps to value” records). Most of them are mapped 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.

Hierarchy

All ICD Family vocabularies have a simple hierarchy, where every concept has only one parent concept. ICD10 Concepts are non-Standard Concepts and therefore do not participate in the hierarchy of the CONCEPT_ANCESTOR table.

ICD10CM

ICD10CM is a coding system used in the USA. It was developed by a component of the US Department of Health and Human Services as an adaptation of the WHO ICD10 coding system, and contains a large number of additions and extensions:

• Laterality of conditions
• Initial encounter, subsequent encounter with the healthcare system
• Routine healing and delayed healing information
• More detail for injuries and external causes of injuries

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.

Transformation

The procedures for transforming Concepts from the source to the OMOP Standard Vocabularies can be found here.

Concept Names

All Concepts are assigned the longest of all available names.

Concept Code

All ICD10CM codes are represented in the format containing the dot.

Standard Concepts

All ICD10CM codes are non-Standard.

Concept Classes

Concept Class	Notes
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

ICD10CM Concept Classes identify each Concept as part of the general coding scheme of diagnoses and disorders, classified into 21 Chapters (not explicitly 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 designated for reimbursement of services, while higher-level codes are non-billing.

Domains

For each ICD10CM Concept, the Domain is inferred from the Target Concept it is mapped to. If an ICD10CM Source Concept is mapped to more than one target SNOMED Concept, a combination Domain is assigned. The ‘Condition’ domain is assigned to all the codes for malignant tumors (those starting from ‘C’).

Domain	Notes
Condition
Condition/Device
Condition/Meas	Only deprecated legacy codes
Measurement
Observation
Procedure

Concept Relationships

For mapping sources, mapping algorithms, and instructions for ETL see ICD10.

Target concept Domain	Number of ICD codes
Condition	111636
Observation	17851
Procedure	611
Measurement	433
Meas Value	131
Device	79
Drug	9

ICD10GM, ICD10CN, CIM10, KCD7

ICD10GM source: International Classification of Diseases, Tenth Revision, German Edition

ICD10CN source: International Classification of Diseases, Tenth Revision, Chinese Edition (CAMS)

CIM10 source: International Classification of Diseases, Tenth Revision, French Edition (ATIH)

KCD7 source: Korean Standard Classification of Diseases and Causes of Death, 7th Revision (STATISTICS KOREA)

Transformation

The procedures for transforming Concepts from the source to the OMOP Standard Vocabularies can be found on the OHDSI GitHub.

Concept Names

Concept names are reused from ICD10 by code where possible. All other names are acquired through translation from the original language to English.

Concept Code

All codes are represented in the format containing the dot.

Standard Concepts

All codes are non-Standard.

Concept Classes

Concept_class for ICD10GM, CIM10, and ICD10CN concepts is adopted from ICD10.

All KCD7 concepts have concept_class ‘KCD7 code’.

Domains

For each Concept, the Domain is inferred from the Target Concept it is mapped to.

Concept Relationships

In most cases, mappings are reused from ICD10. In the case of manual mappings consistency is supported through the CDE.