All diseases are categorised using the International Classifications of Diseases by the World Health Organisation. This is the gold standard for diagnostic health information.
Rare diseases occur across almost all of these disease categories. These include:
Using the ICD, version-11, each disease is assigned it’s own code, and this code is then used in public and private health sectors worldwide to identify new cases (incidence)
and estimate the proportion of total cases in the community (prevalence)
. This helps health systems understand morbidity and mortality rates, assisting them in service provision and estimating associated costs. Support for rare diseases is a priority because the overwhelming majority of rare diseases do not have an ICD number, therefore, their true burden is grossly underestimated.