Evolution of theInternational Classification of Diseases—From Hierarchical Classification to Linguistic Nuance

The US is approaching a crossroads regarding the diagnostic coding system that is used in all patient records and information exchanges that support patient care, research, quality measurement, and payment.In 2022, the International Classification of Diseases, 11th Revision (ICD-11) 1 came into effect.In addition, the World Health Organization (WHO) has ended support for the International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10).The US adopted the International Statistical Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM)in 2015 after a favorable cost-benefit projection and despite recommendations by some prominent health informaticists that adoption should be delayed and planning should begin immediately to ensure a smooth transition from ICD-9-CM to ICD-11. 2 In any case, the mandated adoption of ICD-10-CM further solidified the dependence of the US health care system on the ICD system. 3 Unfortunately, concerns were justified about the costs, difficulties, and disruptions associated with the conversion to ICD-10-CM and about the limited direct clinical benefit to be derived from its