The EORTC QLQ represents a series of validated quality of life (QOL) questionnaires, both fully and partially validated, designed to measure various aspects of life quality in cancer patients and survivors. These tools are used in research to understand better the impact of cancer and its treatments on the health-related well-being of patients from diverse cultural backgrounds.

The EORTC QLQ vocabulary was launched with assistance from the EORTC Working Group.

All EORTC QLQ information is obtained from the Item Library Website.

A special function downloads the source files in JSON format.

Each JSON file is a separate questionnaire, which contains questions, question items, etc.

Then a special script imports the data from these JSON files into special database tables:

• eortc_questionnaires
• eortc_questions
• eortc_question_items
• eortc_recommended_wordings
• eortc_languages

The procedures for transforming Concepts from the source to the OMOP Standard Vocabularies can be found on the OHDSI GitHub.

Concept names are taken directly from the sources, but cleaned of extra spaces, irrelevant symbols, and other unnecessary elements.

The logic for assigning concept codes is custom. To preserve the uniqueness of the concept code, several fields from the sources are used, and these fields vary depending on the type of concept (see Figure 1).

Figure 1. The methodology for assigning concept codes.

Three domains are used in the EORTC QLQ vocabulary: Measurement, Observation, and Meas Value. They are assigned according to the CDM specification.

Concept classes that are used for the questionnaires:

• Core

The main questionnaire was developed to assess the quality of life of cancer patients.

• Module

Supplements to the Core questionnaire by disease-, symptom- and population-specific questionnaires called modules.

• CAT

The CAT groups all item banks for the Computer Adapted Testing system.

• Previous

Previous versions are questionnaires that have been updated.

• Standalone

General questionnaires that can be used without the Core questionnaire.

Concept classes that are used for the scales:

• Symptom Scale
• Time Scale
• Response Scale

Other classes:

• Question
• Issue

Shows the focus of the question.

• Answer
• Direction

Defines a type of situation from the patient's perspective (e.g., feeling pain is in the negative direction).

Concept Class	Standard Concept	Clarification
Time Scale	Non-Standard	Classification concepts are hierarchical concepts for real concepts within the same class. Despite their existence, classification concepts do not participate in the concept_ancestor.
Time Scale	Classification
Symptom Scale	Non-Standard
Symptom Scale	Classification
Response Scale	Non-Standard
Response Scale	Classification
Question	Non-Standard
Question	Classification
Standalone, Previous, Module, Core, CAT	Non-Standard
Issue	Non-Standard
Direction	Non-Standard
Answer	Non-Standard

Table 1. Standardness of the concepts.

Being post-coordinated surveys by nature the content of the vocabulary is treated as non-standard for the majority of data elements ingested. The classificational entries that are added serve as intra-vocabulary classifiers to highlight their intrinsic role/behavior of underlying nonstandard entries.

• There are NO external relationships in the EORTC QLQ vocabulary.
• Internal relationships include (see Table 2 for more details):
  • “Is a/Subsumes” (hierarchical)
  • “Scale of/Has Scale”
  • “Issue of/Has issue”
  • “Direction of/Has Direction”
  • “Answer of/Has Answer”

Concept Class 1	Relationship id	Concept Class 2
Question	Has Answer	Answer
Response Scale
Question	Has Direction	Direction
Question	Has Issue	Issue
[CAT, Core, Module, Previous, Standalone]	Has Scale	Response Scale
		Time Scale
Question		Response Scale
		Time Scale
Question	Is a	[CAT, Core, Module, Previous, Standalone]
		Question
		Symptom Scale
Response Scale		Response Scale
Symptom Scale		[Core, Module, Previous, Standalone]
		Symptom Scale
Time Scale		Time Scale

Table 2. Relationships between concepts based on concept classes.

The vocabulary should be used to populate source fields in the Measurement table in your CDM instances. That means that the description associated with source_value should be matched to concept_name or source_value to split concept_code match should be considered as mapping proxies. Custom lookup tables or source_to_concept_map tables can be utilized to make this mapping possible.

The Vocabulary is expected to be a semantic backbone in analysis using value_source_concept_id (a pilot study).