Psychometric Analysis of the Modified Covid-19 Yorkshire Rehabilitation Scale (C19-Yrsm) in a Prospective Multicentre Study

Bckground Long COVID is a novel multisystem clinical syndrome affecting millions of individuals worldwide. The modified COVID-19 Yorkshire Rehabilitation Scale (C19-YRSm) is a condition-specific patient-reported outcome measure designed for assessment and monitoring of people with Long COVID (LC). Objectives To evaluate the psychometric properties of the C19-YRSm in a prospective sample of people with Long COVID. Methods 1314 patients attending UK specialist Long COVID clinics completed C19-YRSm and EQ-5D-5L longitudinally. Scale characteristics were derived for C19-YRSm subscales (Symptom Severity, SS; Functional Disability, FD; and Overall Health, OH) and internal consistency (Cronbach’s alpha). Convergent validity was assessed using the FACIT-Fatigue scale. Known groups validity was assessed for the Other Symptoms (OS) subscale as tertiles, hospitalisation and intensive care admission. Responsiveness and test-retest reliability was evaluated for C19-YRSm subscales and EQ-5D-5L. The minimal important difference (MID) and minimal clinically important difference (MCID) were estimated. Confirmatory factor analysis was applied to determine the instrument’s two-factor structure. Results C19-YRSm demonstrated good scale characteristic properties. Item-total correlations were between 0.37 to 0.65 (for SS and FD), with good internal reliability (Cronbach’s alphas >0.8). Item correlations between subscales ranged between 0.46 to 0.72. Convergent validity with FACIT was good (−0.46 to −0.62). The three subscales discriminated between different levels of symptom burden (p<0.001), and between patients admitted to hospital and intensive care. There was moderate responsiveness for the three subscales ranging from 0.22 (OH) to 0.50 (SS) and was greater than the EQ-5D-5L. Test-retest reliability was good for both SS 0.86 and FD 0.78. MID was 2 for SS, 2 for FD, and 1 for OH; MCID was 4 for both the SS and FD. The factor analysis supported the two-factor SS and FD structure. Conclusions The C19-YRSm is a condition-specific, reliable, valid, and responsive patient-reported outcome measure for Long COVID. What is already known on this topic Long Covid or Post-COVID-19 syndrome is a multisystem, fluctuating condition. C19-YRSm is literature’s first condition-specific patient reported outcome measure which needed validation in a large population sample. What this study adds C19-YRSm is a valid, reliable, responsive and easy to administer measure which is able to show clinically meaningful change in the status of the condition in people living with Long Covid. How this study might affect research, practice or policy C19-YRSm can be used in clinical and research settings to reliably capture the condition trajectory and the effect of interventions and also help inform clinical policy. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This research is supported by National Institute for Health Research (NIHR) long COVID grant (Ref COV-LT-0016) ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Ethics approval for the LOCOMOTION study was obtained from the Bradford and Leeds Research Ethics Committee on behalf of Health Research Authority and Health and Care Research Wales (reference: 21/YH/0276) I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present work are contained in the manuscript