Validation of a patient-reported outcome measure for giant cell arteritis
No Thumbnail Available
All Authors
Ndosi,Mwidimi
Almeida,Celia
Dawson,Jill
Dures,Emma
Greenwood,Rosemary
Bromhead,Alison
Guly,Catherine
Stern,Steve
Hill,Catherine
Mackie,Sarah
LTHT Author
Mackie, Sarah
LTHT Department
NIHR Leeds Biomedical Research Centre
Rheumatology
Rheumatology
Non Medic
Publication Date
2024
Item Type
Article
Language
Subject
Subject Headings
Abstract
Objectives GCA is systemic vasculitis manifesting as cranial, ocular or large vessel vasculitis. A prior qualitative study developed 40 candidate items to assess the impact of GCA on health-related quality of life (HRQoL). This study aimed to determine final scale structure and measurement properties of the GCA patient reported outcome (GCA-PRO) measure. Methods Cross-sectional study included UK patients with clinician-confirmed GCA. They completed 40 candidate items for the GCA-PRO at times 1 and 2 (3?days apart), EQ-5D-5L, ICECAP-A, CAT-PROM5 and self-report of disease activity. Rasch and exploratory factor analyses informed item reduction and established structural validity, reliability and unidimensionality of the final GCA-PRO. Evidence of validity was also established with hypothesis testing (GCA-PRO vs other PRO scores, and between participants with 'active disease' vs those 'in remission') and test杛etest reliability. Results The study population consisted of 428 patients: mean (s. d.) age 74.2 (7.2), 285 (67%) female; 327 (76%) cranial GCA, 114 (26.6%) large vessel vasculitis and 142 (33.2%) ocular involvement. Rasch analysis eliminated 10 candidate GCA items and informed restructuring of response categories into four-point Likert scales. Factor analysis confirmed four domains: acute symptoms (eight items), activities of daily living (seven items), psychological (seven items) and participation (eight items). The overall scale had adequate Rasch model fit (?2?=?25.219, degrees of freedom?=?24, P ?=?0.394). Convergent validity with EQ5D-5L, ICECAP-A and Cat-PROM5 was confirmed through hypothesis testing. Internal consistency and test杛etest reliability were excellent. Conclusion The final GCA-PRO is a 30-item, four-domain scale with robust evidence of validity and reliability in measuring HRQoL in people with GCA.
Journal
Rheumatology