ICD serves a broad range of uses globally and provides critical knowledge on the extent, causes and consequences of human disease and death worldwide via data that is reported and coded with the ICD. Clinical terms coded with ICD are the main basis for health recording and statistics on disease in primary, secondary and tertiary care, as well as on cause of death certificates. These data and statistics support payment systems, service planning, administration of quality and safety, and health services research. Diagnostic guidance linked to categories of ICD also standardizes data collection and enables large scale research.

For more than a century, the International Classification of Diseases (ICD) has been the basis for comparable statistics on causes of mortality and morbidity between places and over time. Originating in the 19th century, the latest version of the ICD, ICD-11, was adopted by the 72nd World Health Assembly in 2019 and came into effect on 1st January 2022. ICD operates within the framework of WHO’s Constitutional mandate to establish international nomenclatures, the International Health Regulations’ requirement for Member State surveillance capacity, the WHO Nomenclature regulations and the emerging architecture for international sharing of health information. As the openly permitted, Member-State-governed terminology for clinical documentation and statistical aggregation, ICD provides the foundation that these frameworks require — including for the lawful use of health data in research, public health, and the training of AI systems supporting clinical care.

For definitions and classifications of ASD, see section 6A02 of the guide.