Reaching multidisciplinary consensus on classification of anaphylaxis for the eleventh revision of the World Health Organization's (WHO) International Classification of Diseases (ICD-11).

BACKGROUND: Although currently misclassified in the International Classification of Diseases (ICD) and still not officially listed as a rare disease, anaphylaxis is a well-known clinical emergency. Anaphylaxis is now one of the principal headings in the "Allergic and hypersensitivity conditions" section recently compiled for the forthcoming 11th Revision of ICD (ICD-11). We here report the building process used for the pioneering "Anaphylaxis" subsection of ICD-11 in which we aimed for transparency as recommended in the ICD-11 revision guidelines. RESULTS: During an online intensive scientific and technical discussions with ICD-11 Topic Advisory Groups and Expert Working Groups, we drafted a total of 35 proposals for the classification of anaphylaxis. From all the 35 proposals, 77% were implemented, 20% remain to be implemented, and the others being partially implemented (1.5%) or rejected (1.5%). CONCLUSION: For the first time, anaphylaxis is now properly classified and has attained greater visibility within ICD. In addition to all the benefits expected from the actions we have undertaken in updating the terminology, definitions and classification of allergic and hypersensitivity conditions for ICD-11, we strongly believe that anaphylaxis should be a public health priority and that it should therefore be formally added into the list of rare diseases in order to support awareness and quality clinical management of patients.