New Allergic and Hypersensitivity Conditions Section in the International Classification of Diseases-11

Allergy and hypersensitivity, originally perceived as rare and secondary disorders, are one of the fastest growing conditions worldwide becoming a major public health problem, and numerous reports over the last 20 years have been indicating that the world is dealing with an allergy epidemic. They can be expressed in many different organs, with variability of severity degrees, and in any age group, having a significant impact on the quality of life of patients and their families.1, 2 Every health professional can face them; however, they cannot be adequately tracked by international health classification and coding systems, such as the International Classification of Diseases (ICD). As an example, in 2012, we confirmed the under notification of anaphylaxis deaths due to difficult coding under the ICD-10 using the Brazilian national database,3 which impacts the lack of epidemiological data to support public and private decision-making to offer appropriate treatment, such as auto-injectable adrenaline, still missing in some countries. Apart from mortality data, morbidity investigations are also likely to be affected by the difficult ICD coding of these conditions. The following publications drew attention to the inadequacy of the ICD-10 (2010 version) and ICD-11 (May 2014 version) frameworks for recording all allergic and hypersensitivity conditions.4

The ICD is a key instrument of the World Health Organization (WHO) and a member of the WHO Family of International Classifications (WHO-FIC), which seeks to provide a public global standard to organize and classify information about diseases and related health problems. If the records are unable to provide reliable data, decreasing the visibility of some conditions in detriment to the others, there is a possibility of negative outcomes in health decision-making and management actions, affecting the supply and demand of goods and services in both national and global levels. This also results in poor understanding of their natural history and lack of knowledge of their epidemiology.

Considering the ongoing ICD-11 revision an unique opportunity to standardize coding definitions not just for anaphylaxis but for all hypersensitivity/allergic disorders, we organized an international collaboration of regional Allergy Academies, first including the European Academy of Allergy and Clinical Immunology (EAACI), the World Allergy Organization (WAO), the American Academy of Allergy Asthma and Immunology (AAAAI) and then the Latin American Society of Allergy, Asthma and Immunology (SLAAI), the Asia Pacific Association of Allergy, Asthma and Clinical Immunology (APAAACI), and the American College of Allergy, Asthma and Immunology (ACAAI). The joint Allergy Academies have been coordinating a strategic action plan and tremendous efforts since 2013 to provide a better classification of these disorders in the new ICD-11. We first conducted an international survey and demonstrated that the ICD is the most frequently used classification system by the allergy community worldwide; however, it was not considered appropriate in clinical practice.5

Early bilateral discussions with the representatives of the ICD-11 revision group have been put in place, and comments have been submitted to the ICD-11 beta draft platform. A careful comparison between ICD-10 and ICD-11 beta phase for allergy/hypersensitivity conditions codes allowed the identification of gaps and trade-offs4 and supported the construction of a classification proposal. The building process of this model was delineated by ICD/WHO rules, updated by the most recent publications and with the aim to be used by allergists, non-allergists and non-physicians. This classification proposal was validated by crowdsourcing allergist leaderships' community.6 The high level complex structure underwent a cross-linking terms process to contribute to aligning the allergic and hypersensitivity conditions classification to the ICD-11 beta draft facilitating the classification proposal acceptance.7

The proposed model has been presented to the WHO groups in charge of the ICD revision in December 2014. The strategies used and the collaboration from Academies were acknowledged, and the classification proposal has been well accepted. Advised by these groups, we performed a technical process of simplification in an attempt to better fit it to the ICD-11 framework.

WHO asked to simplify the document to facilitate the alignment of the allergic and hypersensitivity conditions classification ICD-11 beta draft facilitating its acceptance.6 The final simplified version counted by using 215 terms, but kept the same original structure and the philosophy used for its construction.

The main outcome of the process was the offer to include a section addressed to "allergic and hypersensitivity conditions" (Table) into the ICD-11 framework, allowing a big picture of these conditions, previously undernotified or misclassified in global health registries.

Table 1
The new "Allergic and hypersensitivity conditions" ICD-11 chapter6, 8

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The tuned version of the allergic and hypersensitivity conditions classification as well as the list of missing terms endorsed by WHO and related Topic Advisory Groups (TAGs) (Pediatric, Dermatology, Rare Diseases, Ophthalmology, Internal Medicine) was the basis of the construction of the new "Allergic and hypersensitivity conditions" section parented under the "Disorders of the Immune System" chapter (Table). Upon WHO guidance, all the proposals have been submitted into the ICD-11 beta draft platform and during this process, with the aim of reaching a harmonized view regarding overlapping conditions, we have been in contact with relevant WHO TAGs and working groups (WG). Once the classification is included into the ICD-11 framework, our aim is to carry on working in collaboration with WHO in order to validate/disseminate the classification by field trial.

Having a classification able to capture conditions in health international information systems in a realistic manner is crucial to the identification of potential problems, and in a wider system, can identify contextually specific service deficiencies and provide the impetus for changes. The new allergic and hypersensitivity conditions section into the ICD-11 framework8 gave a unit for a specialty previously considered with less importance. Since most of the allergic and hypersensitivity conditions have been considered noncommunicable diseases, the WHO has been cosigning initiatives to support changes in the same direction, such as for the asthma under the Global Alliance against Chronic Respiratory Diseases (GARD) or for the nomenclature of allergens under the WHO/International Union of Immunological Societies (IUIS). These changes will allow us to monitor the balance between health and allergic/hypersensitivity disease worldwide to understand public policies required to support organized high-impact measures and affordable interventions to prevent, promote health by assuring the access to appropriate care, and improve the quality of life of the population as a whole.

The final ICD-11 framework will be presented to the World Health Assembly in the next few years. We are aware that the revision process is not set and that the current structure may be tuned according to further implementations and adaptations; however, we believe that the ICD revision innovative process, allowing stakeholders to be involved, is critical to increases in the acceptability as well as the accuracy of use of this classification system. This opened and transparent transition allows conditions previously invisible or undernotified to be well classified, which will change dramatically the landscape in which the health system operates.

Currently, we are unable to objectively measure the consequences of these changes in the ICD framework, but we strongly believe that the outcomes of all past and future actions will impact positively as an aggregate data to perform positive quality-improvement in health professional clinical practice as well as can contribute to strengthening the identity of the allergy specialty.