Mapping the EORTC item library to the World Health Organization international classification of functioning, disability and health: a content analysis

PURPOSE: The European Organisation for Research and Treatment of Cancer (EORTC) questionnaires are some of the most widely used patient-reported outcome measures (PROMs) for health-related quality of life assessment in oncology. The EORTC Item Library is an online platform comprising all EORTC PROMs that enables the creation of customised questionnaires (item lists). To characterise and better understand the breadth of functioning, disability and health coverage within the EORTC Item Library, this study aimed to link and analyse its content using the International Classification of Functioning, Disability and Health (ICF). METHODS: A team of reviewers applied the most recent ICF linking rules to map the items currently included in the EORTC Item Library. Descriptive analysis was used to summarise the content covered in ICF categories and concepts coded as not covered or not definable. RESULTS: The 1076 EORTC items covered 1860 concepts overall, with most (n = 1641, 88.2%) linked to the ICF. Concepts were linked to the majority of ICF chapters (n = 28/30, 93.3%), covering 60.9% (168/276) of all second-level ICF categories. The components of 'b-Body functions' and 'd-Activities and participation' had the highest coverage, with concepts linked to 80.0% (64/80) and 68.5% (63/92) of all second-level categories respectively. CONCLUSIONS: The EORTC Item Library provides broad coverage of functioning, disability and health within the ICF. Using the ICF to describe its content can inform the selection of EORTC items and PROMs and facilitate standardised comparison across measures and contexts, supporting the use and interpretation of EORTC measures in research and clinical practice.