International Statistical Classification of Diseases and Related Health Problems
The International Classification of Diseases (ICD) is the international "standard diagnostic tool for epidemiology, health management and clinical purposes." Its full official name is International Statistical Classification of Diseases and Related Health Problems.
The ICD is originally designed as a health care classification system, providing a system of diagnostic codes for classifying diseases, including nuanced classifications of a wide variety of signs, symptoms, abnormal findings, complaints, social circumstances, and external causes of injury or disease. This system is designed to map health conditions to corresponding generic categories together with specific variations, assigning for these a designated code, up to six characters long. Thus, major categories are designed to include a set of similar diseases. ICD-11 is a major step forward, because it has the necessary terminological and ontological elements for seamless use in digital health.
The ICD is published by the WHO and used worldwide for morbidity and mortality statistics, reimbursement systems, and automated decision support in health care. This system is designed to promote international comparability in the collection, processing, classification, and presentation of these statistics. Like the analogous Diagnostic and Statistical Manual of Mental Disorders (which is limited to psychiatric disorders and almost exclusive to the United States), the ICD is a major project to statistically classify all health disorders, and provide diagnostic assistance. The ICD is a core statistically based classificatory diagnostic system for health care related issues of the WHO Family of International Classifications (WHO-FIC).
The ICD is revised periodically and is currently in its 10th revision. ICD-10, as it is therefore known, is from 1992 and the WHO publishes annual minor updates and triennial major updates. The eleventh revision of the ICD (ICD-11) was accepted by WHO's World Health Assembly (WHA) on 25 May 2019 and will come into effect on 1 January 2022.