WASP

Developed by: Tessa Ohlsen

WASP is an acronym for Web Application supporting SNOMED CT Postcoordination. For this, WASP utilizes the SNOMED CT Machine Readable Concept Model and supports the SNOMED CT Expression Template Language. This work was published in a 2023 paper in Applied Sciences.

With the national license, the interest and use of SNOMED CT in Germany increases. The postcoordination of concepts is often avoided due to its complexity and lack of software support, although this is exactly what makes SNOMED CT a flexible and powerful interlingua. Therefore, a web application called WASP was developed to support the creation of postcoordinated SNOMED CT expressions (PCE). The syntactic and semantic rules specified by SNOMED CT (Compositional Grammar and Concept Model) are ensured. To use WASP the folder “wasp” must be stored locally. This folder contains the templates defined by SNOMED International defined templates and other relevant files. A custom terminology server can be stored in the file server.json. It is a requirement for the use of WASP that a version of SNOMED CT in the desired edition is available on the TS WASP has three functions: Creation of a PCE expression based on the Concept Model, Creation of a PCE expression based on templates and Generation of own templates.

Creating a PCE based on the Concept Model.

The focus concept, which contains the primary clinical fact, is first entered into the input field. Based on the input, the respective Concept Model Domain is determined by WASP. The SNOMED CT attributes that are based on the Concept Model Domain and are relevant for a use case can be selected. In addition, the attribute relationships that are present in the focus concept definition are automatically loaded. This is displayed in the table “Attribute summary”. The attribute value is selected at the bottom of the right side in the section “Attribute value”. Finally, the PCE is created again based on the Compositional Grammar. This can be stored in a FHIR CodeSystem Supplement.

Excerpt from WASP for the creation of a PCE based on the Concept Model.

PCE based on a template

First, a template is selected. The selection is facilitated by an internal repository in the locally file system that contains templates defined by SNOMED International and templates generated by users. A filtering mechanism by category (i.e., by the semantic tag of the focus concept) can be used to limit the number of choices. Compared to the variant explained earlier, only attributes defined in the template can be used to generate the PCE based on the templates. Then, the attribute values are selected based on the value ranges defined in the template. Finally, the PCE is created again and can also be stored in a FHIR CodeSystem Supplement.

Excerpt from WASP for the creation of a PCE based on a template

Generation of own templates

The generation of custom templates is methodically similar to the creation of PCE based on the Concept Model. Once again, a focus concept is selected depending on the use case as well as relevant attributes based on the respective Concept Model Domain. Instead of a concrete attribute value, a range of values is defined based on the Concept Model Domain or the concept definition of the focus concept by using constraint operators. Cardinalities for attribute relationships and role groups are also defined. Subsequently, a name and a so-called term template (template for generating a description for the PCE) are formed. The created template is stored in the download and can be added to the repository of the other templates.

Excerpt from WASP for the generation of own templates.