Patient Uncertainty Questionnaire-Rheumatology (PUQ-R-R): development and validation of a new self-report instrument using modern psychometrics

Abstract

The objective of this study was to develop and evaluate a new instrument for patient uncertainty in systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). Cognitive debriefing was used to pre-test the initial items generated on the basis of the preliminary qualitative exploration. Two field tests were conducted across five UK hospitals to evaluate the measurement properties of the new instrument using the modern psychometric technique of Rasch Measurement Theory (RMT). Traditional psychometric techniques were also used to complement and further assess the construct validity. Pre-testing supported the relevance, acceptability and comprehensibility of the initial items. Findings indicated that the new PUQ-R instrument fulfilled the expectations of RMT to a large extent and comprises five scales; symptoms and flares, medication, trust in doctor, self-management and impact which further displayed excellent measurement properties as assessed against the traditional psychometric criteria (including Cronbach`s alpha 0.82 – 0.93). Preliminary construct validity analyses indicated patient uncertainty is associated with treatment-adherence, mood and aspect of quality of life but not disease activity. By quantifying uncertainty, the PUQ-R can support evidence-based management programmes and research.