Validation of a new glucocorticoid-specific Patient-Reported Outcome Questionnaire (the Steroid PRO)

Bridgewater, Susan; Ndosi, Mwidimi; Dawson, Jill; Richards, Pamela; Silverthorne, Christine; Dures, Emma; Goodman, Susan M.; Hill, Catherine; Mackie, Sarah L.; Robson, Joanna C.

Abstract

Objectives: Glucocorticoids used in the treatment of inflammatory rheumatic conditions can impact on health-related quality of life. An underpinning qualitative study developed a long-list of candidate items for a treatment-specific patient-reported outcome (PRO) measure. The objective of this paper is to determine scale structure and psychometric properties of the Steroid PRO. Methods: A cross-sectional survey of adults from the UK, USA, Australia and New Zealand, taking glucocorticoids for a rheumatic disease. Initial survey collected demographics, clinical information, 40 Steroid PRO candidate items and EuroQol-5 Dimensions- 5 levels (EQ-5D-5L). Follow-up, 3-5 days later, collected Steroid PRO candidate items and a condition-change ( € transition') question. Analysis included Rasch measurement model, exploratory factor analysis (EFA), and hypothesis testing for discriminative validity, convergence validity and test-retest reliability. Results: Total responses 946: UK n=743 (79%); USA n=139 (15%); Australia/New Zealand n=64 (7%); mean age 57.6 (SD=13.6); 833 (88%) women. Participants with inflammatory arthritis n=197 (21%), connective tissue disease and/or vasculitis n=402 (42%), giant cell arteritis and/or polymyalgia rheumatica n=347 (37%). Twenty-five items were removed due to lack of fit to Rasch model. Of the remaining items, EFA suggested four subscales: Social impact (4 items); Impact on appearance (3 items); Psychological impact (5 items); Treatment concerns (3 items). Rasch modelling supported a four-subscale structure and total score, confirming construct validity and reliability. Hypothesis testing confirmed discriminant and convergence validity. Intraclass correlation coefficient (total score) was 0.809 demonstrating excellent (test-retest) reliability. Conclusions: The Steroid PRO is a 15-item, valid and reliable scale for measuring the impact of glucocorticoid therapy in people with rheumatic diseases.

• Journal Article Type: Article
• Acceptance Date: Oct 24, 2023
• Online Publication Date: Nov 10, 2023
• Publication Date: Feb 15, 2024
• Deposit Date: Oct 24, 2023
• Publicly Available Date: Apr 11, 2024
• Journal: Annals of the Rheumatic Diseases
• Print ISSN: 0003-4967
• Electronic ISSN: 1468-2060
• Publisher: BMJ Publishing Group
• Peer Reviewed: Peer Reviewed
• Volume: 83
• Issue: 3
• Pages: 394-400
• DOI: https://doi.org/10.1136/ard-2023-224946
• Keywords: Systemic vasculitis, Connective Tissue Diseases, Arthritis, Rheumatoid, Glucocorticoids, Patient Reported Outcome Measures
• Public URL: https://uwe-repository.worktribe.com/output/11392736