Clinical functioning information tool – coronavirus disease 2019 (ClinFIT COVID-19): psychometric evaluation and development of an interval-scaled functioning score across the care continuum

Objective: to report on the development and global testing of the COVID-19 version of the International Classification of Functioning, Disability and Health-based Clinical Functioning Information Tool called “ClinFIT COVID-19” to collect functioning data of rehabilitation patients across the care continuum to establish an interval-scaled functioning score. Design: Multicentre, cross-sectional observational study. Subjects/Patients: Rehabilitation patients in acute, post-acute, and long-term settings. Methods: Three context-specific versions (13–16 ICF categories) of ClinFIT-COVID-19 were administered to collect information on patient functioning. Rasch analysis examined psychometric properties and generated conversion tables from ordinal raw scores to a 0–100 interval metric. Results: Twenty-six study centres in 17 countries across the globe collected data from 1,747 patients. Problems in exercise tolerance functions were most frequently reported in the acute and post-acute settings (74.2%; 87.6%), while long-term care patients most frequently reported pain as problematic (71.1%). With a testlets approach and item splitting, all 3 ClinFIT COVID-19 versions satisfied Rasch model expectations (item-trait χ² p > 0.05; PSI 0.742–0.812), making it feasible to develop respective transformation tables. Conclusion: This study found the psychometric properties of ClinFIT COVID-19 acceptable. Future studies are needed to validate the use of the transformation tables to monitor functioning and evaluate intervention impact.