Authoring is the process of defining the relationship between concepts in the source code system and the target code systems.

Authors can assign none, one or more target codes to a source code and assign a relationship type.

When assigning a target code, authors need to take into account the map use case and purpose as well as the code systems structure, rules, term composition and granularity when developing a map.

Automated mapping tools

Once data has been pre-processed, automated mapping tools may be useful. Automated mapping is when computer algorithms are used to create maps between code systems. Lexical mapping, where the structure of the
words in the clinical term is compared and analyzed as to whether the words are the same, similar or different, is often incorporated within automatic mapping.

Maps generated by a tool need to be checked by a specialist mapper. Significant care must be taken with automated mapping, because severe mapping errors can result if not done in a controlled way. Automated mapping, in conjunction with human review (and manual remapping where necessary), is likely to achieve better results than automated mapping alone.

Appropriate filters or scope constraints should be used on the tool to increase accuracy of the automated mapping tools. A record of the tool, the scope constraint and matches should be kept to test reproducibility of methods

Manual/human mapping

Human mapping is the use of human knowledge and skill to author maps. Each map is built singly and individually. The process requires examination of each and every concept in the coding system. Informed judgments or decisions are made about the shared meaning of concepts. Electronic or computational tools are used, but only in support of work process.

There are a some tools available to assist in this process, however manually mapping into tables without tooling support (e.g. spreadsheets) is time consuming and can be error prone due to needing to copy and paste from a browser and into the table.

Editorial guidelines

Defining firm guidelines for mappers will save time and go a long way towards ensuring higher levels of inter-rater reliability in situations where there is more than one mapper.  These guidelines will also be valuable in highlighting the reasons why certain target concepts were chosen over others.  Editorial Guidelines are very important to users of the maps and are a necessary development step in the creation of useful, reliable and usable maps. 

Also a map is not necessarily static, future versions of a map may require a change of decisions or rules which need to be clearly defined and applied consistently.

Tips

Organising your terms by grouping together terms of a similar nature, for example: all terms referring to fractures together, all the diabetes terms together can make the mapping process easier and aid in consistency of the maps.  Once this is done also consider if the source code system contains terms that might be considered “synonyms” or duplicates of other terms.

It may be possible to request new content from the code system suppliers (e.g. SNOMED International)  to deliver a better map