WHOThe International Classification of Diseases (ICD) is the cornerstone of global health information standards, providing the universal coding system through which diseases, injuries, and causes of death are recorded and compared worldwide. Legally mandated under the WHO Constitution and Nomenclature Regulations, ICD has provided comparable health statistics for over 150 years. The current revision, ICD-11, came into effect on 1 January 2022 and represents the first fully digital, interoperable edition of the classification.
Background
The origins of ICD trace back to the International List of Causes of Death, first adopted in 1893 by the International Statistical Institute. The World Health Organization assumed responsibility for the classification upon its founding in 1948, when the First World Health Assembly entrusted WHO with establishing and revising international nomenclatures of diseases and causes of death. The sixth revision (ICD-6, 1948) became the first edition to include morbidity conditions alongside mortality. Subsequent revisions expanded scope and granularity across decadal timescales:
| Revision | In Effect | Adopted |
|---|---|---|
| ICD-6 | 1948 | 1948 (WHA1.36) |
| ICD-7 | 1 Jan 1958 | May 1956 (WHA9.29) |
| ICD-8 | 1 Jan 1968 | May 1966 (WHA19.44) |
| ICD-9 | 1 Jan 1979 | May 1976 (WHA29.34) |
| ICD-10 | 1 Jan 1993 | May 1990 (WHA43.24) |
| ICD-11 | 1 Jan 2022 | May 2019 (WHA72.15) |
ICD-11 was endorsed by the 72nd World Health Assembly in May 2019. As of May 2024, 132 member states are at various phases of ICD-11 implementation: 72 countries have commenced implementation including translation efforts, 50 are conducting or expanding pilots, and 14 have begun collecting or reporting data using ICD-11 coding.
Purpose & Scope
ICD serves as the international standard for recording, analyzing, interpreting, and comparing mortality and morbidity data. The WHO page identifies the following primary use cases:
- Certification and reporting of causes of death -- standardized mortality statistics providing long-term health trends and short-term epidemiological monitoring
- Morbidity coding and reporting -- recording diagnoses across primary, secondary, and tertiary care
- Casemix and Diagnosis-Related Grouping (DRG) -- resource allocation and lump-sum payment groupings
- Quality and safety assessment -- monitoring patient safety incidents and treatment outcomes
- Cancer registries -- detailed information on cancer type, location, spread, and behavior
- Antimicrobial resistance (AMR) -- recording infection agents and resistance patterns per GLASS recommendations
- Clinical trials and research -- pooling comparable coded information across multilingual sites
- Functioning assessment -- functioning categories based on WHODAS2
- Traditional medicine -- ICD-11 enables, for the first time, counting of traditional medicine services and encounters
- Digital interoperability -- multilingual COVID-19 vaccine certificates and digital health guidelines
ICD-11 Highlights
ICD-11 is designed as an end-to-end digital solution with API access, online and offline tools, and a conceptual framework independent of language and culture. Key features include:
- Integration of terminology and classification in a single system
- Creative Commons Attribution-NoDerivs 3.0 IGO license, making it freely accessible
- Available in 10 official languages (Arabic, Chinese, Czech, English, French, Portuguese, Russian, Spanish, Turkish, Uzbek) with 25 additional translations underway
- ICD-11 2024 release introduced over 200 new allergen codes and the candidate DORIS (Digital Open Rule Integrated Cause of Death Selection) tool
- ICD-11 2026 release published 16 February 2026
- Mappings to MedDRA, medical device nomenclature, Orphanet terminology, MONDO Disease Ontology, and explorations with LOINC
Governance & Maintenance
ICD is governed by the World Health Organization through its Classifications and Terminologies unit. The WHO Family of International Classifications (WHO-FIC) network, comprising collaborating centers in multiple countries, contributes to revision and maintenance through annual meetings. ICD-11's digital architecture supports incremental updates more frequently than the historical decadal revision cycle.
Related Standards
- MeSH -- the Medical Subject Headings vocabulary for indexing biomedical literature, complementary to ICD
- SNOMED CT -- a more granular clinical terminology often used alongside ICD
- ICF -- International Classification of Functioning, Disability and Health, a sibling WHO classification
- ICHI -- International Classification of Health Interventions, another WHO-FIC member