Objectives To finalise and validate a disease-specific patient-reported outcome (PRO) measure: the ANCA-associated vasculitis patient-reported outcome (AAV-PRO) questionnaire. Using a 35-item candidate questionnaire developed following 50 qualitative interviews in the UK, USA and Canada, a longitudinal survey was conducted to determine the final scale structure and validate the AAV-PRO.
Methods Participants were recruited via Vasculitis UK and the Vasculitis Patient-Powered Research Network. The 35-item candidate questionnaire was completed at baseline and 3 months; UK participants completed the EuroQol-5D-5L (EQ-5D-5L), while US participants completed a test–retest exercise, 3–5 days after baseline. Scale structure was defined using exploratory factor analysis (EFA) and Rasch analysis. Convergent and known groups validity, test–retest reliability and longitudinal construct validity were assessed.
Results There were 626 participants with AAV; >25% reporting ‘active disease’. EFA and Rasch analysis supported a 29-item profile measure comprising six domains: ‘organ-specific symptoms’, ‘systemic symptoms’, ‘treatment side effects’, ‘social and emotional impact’, ‘concerns about the future’ and ‘physical function’. Mean domain scores were higher for participants with ‘active disease’ versus ‘remission’ (p<0.001). Construct validity was demonstrated by correlations between domain scores and the EQ-5D-5L (range r=−0.55 to 0.78), all p<0.0001. In participants reporting ‘no change’ (n=97) during the test–retest, intraclass correlation coefficient values were high (range 0.89–0.96) for each domain.
Conclusions The AAV-PRO, a new disease-specific PRO measure for AAV, has good face and construct validity, is reliable, feasible and discriminates among disease states.
- granulomatosis with polyangiitis
- systemic vasculitis
- patient perspective
- outcomes research
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JR and JD contributed equally.
Handling editor Josef S Smolen
Contributors JR and JD contributed equally to this study. JR planned the study, wrote the study protocol and documentation, arranged data entry, clinical input and interpretation of Rasch and EFA analyses, drafted and amended final manuscript. JD planned the study, commented on study protocol and documentation, performed EFA and descriptive statistics and reviewed final document. HD commented on study protocol, performed Rasch analysis and reviewed final document. PFC, NM, KK, SA, EE, DG, JM, JP, RAL, JAS, GT and PAM commented on study protocol and documentation including patient information and design of the survey, commented on results and on all drafts of the manuscript. In addition, JM facilitated UK survey and PAM facilitated US survey.
Funding Sponsored by the University of Oxford and the Vasculitis Clinical Research Consortium (VCRC). Funding for the development of the PRO was received from the Medical Research Fund, Oxford, the Oxfordshire Health Services Research Committee Ref. 1098, and a Patient-Centered Outcomes Research Institute Pilot Project Grant. The VCRC has received support from the US National Institute of Arthritis and Musculoskeletal and Skin Diseases (U54 AR057319 and U01 AR51874), the National Center for Research Resources (U54 RR019497); and the Office of Rare Diseases Research and the National Center for Advancing Translational Science. The VCRC is part of the Rare Diseases Clinical Research Network (RDCRN). JR and RAL were supported in part by the National Institute for Health Research Musculoskeletal Biomedical Research Unit, Oxford, UK. JR was supported by a National Institute for Health Research (NIHR) clinical lectureship. NM was supported by a UCB/Canadian Rheumatology Association/Arthritis Society postgraduate rheumatology fellowship award and a research fellowship from the Department of Medicine at the Ottawa Hospital. Oxford University Innovation provided funding of translatability assessment.
Competing interests None declared.
Patient consent Obtained
Ethics approval Medical Sciences IDREC, University of Oxford, Oxford, Ref: MS-IDREC-C1-2015-087, for the UK and US survey. In the USA, approval was also given by the Institutional Review Boards at the University of Pennsylvania and the University of South Florida, Ref: Pro00018514.
Provenance and peer review Not commissioned; externally peer reviewed.
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