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

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

doi:10.1136/ard-2023-224946

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

Ann Rheum Dis. 2024 Feb 15;83(3):394-400. doi: 10.1136/ard-2023-224946.

Authors

Susan Bridgewater^#^{1

2}, Mwidimi Ndosi^#^{1

2}, Jill Dawson³, Pamela Richards^{1

2}, Christine Silverthorne^{1

2}, Emma Dures^{1

2}, Susan M Goodman⁴, Catherine Hill^{5

6}, Sarah L Mackie⁷, Joanna C Robson^{8

2}

Affiliations

¹ School of Health and Social Wellbeing, University of the West of England, Bristol, UK.
² Rheumatology Department, University Hospitals Bristol and Weston NHS Foundation Trust, Bristol, UK.
³ Nuffield Department of Population Health, University of Oxford, Oxford, UK.
⁴ Rheumatology Department, Hospital for Special Surgery, New York, New York, USA.
⁵ Rheumatology Department, The Queen Elizabeth Hospital, Adelaide, South Australia, Australia.
⁶ Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, South Australia, Australia.
⁷ Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, Leeds, UK.
⁸ School of Health and Social Wellbeing, University of the West of England, Bristol, UK Jo.Robson@uwe.ac.uk.

^# Contributed equally.

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.

Keywords: Arthritis, Rheumatoid; Connective Tissue Diseases; Glucocorticoids; Patient Reported Outcome Measures; Systemic vasculitis.

MeSH terms

Adult
Cross-Sectional Studies
Female
Glucocorticoids / therapeutic use
Humans
Male
Middle Aged
Patient Reported Outcome Measures
Psychometrics
Quality of Life* / psychology
Reproducibility of Results
Rheumatic Diseases* / drug therapy
Steroids
Surveys and Questionnaires

Substances

Glucocorticoids
Steroids