Coding the undiagnosed: Outcomes and recommendations from the RD-CODE project
A set of recommendations from the RD-CODE project have been published in the Orphanet Journal of Rare Diseases, providing guidance for how ORPHAcodes can be used to improve the visibility of undiagnosed patients in health information systems.
ORPHAcodes are the only rare disease-specific medical terminology. Developed and maintained by the Orphanet team, they fill gaps in existing codification systems and help improve the visibility of rare disease patients in health systems. In 2017, the European Commission Steering Group on Health Promotion, Disease Prevention and Management of Non-Communicable Diseases recognised the importance of using ORPHAcodes for the codification of rare diseases, and identified their implementation as a priority area for best practice.
RD-CODE (2019-2021) was a 3-year project funded under the Third EU Health Programme and coordinated by Orphanet in response to this recognition. The goal of the project was to establish rules and guidelines for coding rare diseases to ensure a consistent, standardised, and adequate level of information on rare disease patients to be shared at the European level. These were developed and elaborated through the project’s work to support four Member States (Czech Republic, Malta, Romania, and Spain) in implementing ORPHAcodes into routine coding systems.
One particularly notable achievement of the project was the creation of ORPHAcode ORPHA:616874, “Rare disorder without a determined diagnosis after full investigation.” For the first time, this code allows for patients with undiagnosed rare diseases to be made visible in health information systems, and to be identified as part of the rare community despite the lack of a definitive diagnosis. The importance of this work was recognised by the Spanish Federation for Rare Diseases (FEDER) in 2023, when they honoured Orphanet with an award.
This article presents three recommendations for the coding of undiagnosed patients which emerged from RD-CODE’s work, developed by a multi-stakeholder panel of experts. They are:
- Whenever possible, the diagnostic ascertainment should be captured for all rare disease cases (using options such as “suspected rare disease,” “confirmed rare disease,” and “undetermined diagnosis”);
- In instances where ORPHAcoding has been implemented, the code ORPHA:616874 should be used to document cases where a diagnosis has not been achieved following all reasonable efforts to do so;
- Registries should include a phenotype and genotype description for patients with an undiagnosed designation, in particular using terms from the Human Phenotype Ontology (HPO), Human Genome Variation Society (HGVS), and HUGO Gene Nomenclature Committee (HGNC).
Identifying rare disease patients, particularly those who remain undiagnosed, is vital to improving access to research programs, accelerating treatment development, and shortening the diagnostic odyssey, among other benefits. By implementing the recommendations outlined in this paper, all members of the rare disease community will be able to benefit from visibility in health information systems, rather than only those for whom a diagnosis has been identified.
