Modeling and tools for supporting post-coordination in ICD-11

The World Health Organization (WHO) is working on the 11th revision of the International Classification of Diseases (ICD-11), which is scheduled to be released in 2017. One of the main goals for the revision process was to make ICD-11 ready to be used with electronic health records and information systems. In order to meet this goal, ICD-11 was designed to have an ontological underpinning, commonly referred to as its ”Content Model”. Another significant novelty introduced in ICD-11, compared to ICD-10, is that ICD-11 will allow medical coders to enter details, such as severity and temporal course, as modifiers to the main ICD code. To support this kind of post-coordination, we extended the ICD-11 Content Model and the collaborative ICD authoring tool, iCAT, so that ICD developers can specify which post-coordination axes are allowed for each ICD-11 entity, to specify valid values for each axis from a special ICD-11 chapter where value sets are defined, called Chapter X, and to give selected ICD-11 categories logical definitions, so that equivalence of multiple codes and already defined categories can be established automatically.