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BackgroundThe C19-YRS was the first validated scale reported in the literature for patient assessment and monitoring in Long Covid or Post-COVID syndrome. The 22-item scale contains four subscales measuring symptom severity, functional disability, overall health and additional symptoms.ObjectivesThis study aimed to modify and refine the scale based on psychometric properties, emerging evidence on additional Long Covid symptoms, and feedback from a working group of patients and healthcare professionals.MethodsData were collected from 370 patients who completed the C19-YRS scale in a community Long COVID service. The psychometric properties of the Symptom Severity and Functional Disability subscales were assessed using a Rasch Measurement Theory framework, where all individual scale items were assessed for model fit, local dependency, response category functioning and differential item functioning (DIF) by age group and sex. Additionally, the subscales were assessed for targeting, reliability and unidimensionality. The overall health subscale is a single item, and the additional symptoms subscale is not intended to be summed, therefore neither is appropriate for Rasch analyses. Psychometric results and implications were relayed back to the working group for discussion, alongside clinical evidence of emerging and relevant symptoms not covered by the original C19-YRS.ResultsRasch analysis revealed promising psychometric properties of the symptom severity and functional disability subscales, with both displaying good targeting and reliability, although some individual measurement anomalies were noted. The original 0-10 item response category structure did not operate as intended for both the subscales. Post-hoc rescoring suggested that a 4-point response category structure would be more appropriate for both the subscales, and this aligned with patient feedback. This scoring change was implemented, alongside changes in the item composition of the symptom severity and additional symptoms subscales. The functional disability item set, and the overall health single-item subscale remained unchanged.ConclusionA modified version of the C19-YRS was developed based on a combination of psychometric evidence, clinical relevance of the content and feedback from the working group (comprising patients and healthcare professionals). Future studies including NIHR funded LOCOMOTION study will undertake large-scale, multi-centre validation of the modified C19-YRS. |
