Edition of 29 July 2019

Orphanet maintains a nomenclature and a classification of rare disorders, the only one specific to this field, as well as mappings with other medical terminologies in use, not least ICD-10 (ICD-11 forthcoming).

The Orphanet nomenclature is used to code the diagnosis of a rare disorder with a unique and time-stable identifier, the ORPHAnumber (also named ORPHAcode) in order to facilitate data collection, research and analysis. Several European countries have already adopted the ORPHAcodes to identify rare diseases in their Health Information Systems. Its adoption has been promoted as a best practice by the European Commission Steering Group on Promotion of Health and Prevention of chronic non-communicable diseases (SGPP), what gave rise to an implementation project : RD-CODE.

In order to improve the collection of information on rare diseases, and to share standardised and consistent information at European level, the RD-ACTION published a series of documents (Specifications for an integrated coding application with Orphacodes, Standard procedure and guide for the coding with Orphacodes, Recommendation for routine maintenance of codification resources for rare diseases) to provide recommendations and tools to facilitate the use of ORPHAnumbers in Health Information Systems. The objective of creating these tools is to provide the computable information necessary to achieve implementation of ORPHAnumbers in Health Information Systems, and ensure easier and accurate coding.

To stick with these recommendations, the Orphanet nomenclature has been improved by adding clarity to its internal organisation. In fact, as the Orphanet nomenclature is organised in multi-hierarchical classifications, it might be difficult for unexperienced coders to identify the appropriate code. As recommended by the European Joint Action RD-Action, a reduced list of ORPHAnumbers has been agreed upon in order to allow data sharing and statistical analysis at EU-level. This list, based on the disorder level, excluding groups and subtypes, establishes the “Aggregation level”. The three organisation levels : Groups, Disorders and Sub-types, are now explicit in the implementation files (Orphanet nomenclature space, see below), but also have been added in the Orphanet website to the « identity card » of each clinical entity. Orphadata product 1 will benefit from these evolutions in September.
Also, the fact that an ORPHAcode is active or inactive (because the entity is no longer considered as one by the medical community) is now explicit, so is the referral from an inactive code to an active one in replacement.

A specific space is now dedicated to the Orphanet nomenclature for coding purposes in Orphadata (http://www.orphadata.org/cgi-bin/ORPHAnomenclature.html) in which a yearly nomenclature pack can be dowloaded, as well as the related documentation (http://www.orphadata.org/cgi-bin/img/PDF/ORPHAnomenclaturexmlcontent.pdf), and the link to the past versions and history of modifications (https://github.com/orphanet-rare-diseases-issues/RD-CODE). Furthermore, a dedicated Helpdesk will be launched for assisting implementation, as will be APIs (http://www.rd-code.eu/tools/).