Using Rasch analysis to evaluate the validity of the diabetes-specific version of the Illness Perception Questionnaire-Revised.

This study used Rasch analysis to examine the psychometric validity of the Illness Perception Questionnaire-Revised to assess beliefs about diabetes in 470 participants with Type 2 diabetes and 71 participants with Type I diabetes. All Illness Perception Questionnaire-Revised scales had psychometric issues, which included poorly utilised response categories, poor scale precision and multidimensionality. Following reengineering, only four of the eight scales (Consequences, Illness coherence, Timeline cyclical and Emotional representations) were psychometrically adequate according to the Rasch model. The diabetes-specific version of the Illness Perception Questionnaire-Revised provides suboptimal assessment of beliefs held by patients with diabetes. [ABSTRACT FROM AUTHOR]