Validation of a patient-reported outcome measure for giant cell arteritis

Mwidimi Ndosi; Celia Almeida; Jill Dawson; Emma Dures; Rosemary Greenwood; Alison Bromhead; Catherine Guly; Steve Stern; Catherine Hill; Sarah Mackie; Joanna C Robson

doi:10.1093/rheumatology/kead201

Validation of a patient-reported outcome measure for giant cell arteritis

Rheumatology (Oxford). 2024 Jan 4;63(1):181-189. doi: 10.1093/rheumatology/kead201.

Authors

Mwidimi Ndosi^{1

2}, Celia Almeida^{1

2}, Jill Dawson³, Emma Dures^{1

2}, Rosemary Greenwood⁴, Alison Bromhead^{1

2}, Catherine Guly⁵, Steve Stern^{1

2}, Catherine Hill^{6

7}, Sarah Mackie^{8

9}, Joanna C Robson^{1

2}

Affiliations

¹ School of Health and Social Wellbeing, University of the West of England, Bristol, UK.
² Academic Rheumatology Unit, Bristol Royal Infirmary, University Hospitals Bristol and Weston NHS Foundation Trust, Bristol, UK.
³ Nuffield Department of Population Health (HSRU), University of Oxford, Oxford, UK.
⁴ NIHR Research Design Service South West, University Hospitals Bristol and Weston NHS Foundation Trust, Bristol, UK.
⁵ Bristol Eye Hospital, University Hospitals Bristol and Weston NHS Foundation Trust, Bristol, UK.
⁶ Discipline of Medicine, The University of Adelaide, Adelaide, Australia.
⁷ Rheumatology Unit, Royal Adelaide Hospital, Adelaide, Australia.
⁸ Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, Leeds, UK.
⁹ Leeds Biomedical Research Centre, Leeds Teaching Hospitals NHS Trust, Leeds, UK.

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-retest 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 (χ2 = 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-retest 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.

Keywords: GCA; Rasch analysis; large vessel vasculitis; ocular GCA; patient reported outcome measures; quality of life; temporal arteritis.

MeSH terms

Activities of Daily Living
Aged
Cross-Sectional Studies
Female
Giant Cell Arteritis* / diagnosis
Humans
Male
Patient Reported Outcome Measures
Psychometrics
Quality of Life* / psychology
Reproducibility of Results
Surveys and Questionnaires

Abstract

MeSH terms

Grants and funding