Measurement properties of the Patient-Rated Wrist and Hand Evaluation: Rasch analysis of responses from a traumatic hand injury population

INTRODUCTION: The Patient-Rated Wrist and Hand Evaluation (PRWHE) is a self-reported assessment of pain and disability to evaluate outcome after hand injuries. Rasch analysis is an alternative strategy for examining the psychometric properties of a measurement scale based in item response theory, rather than classical test theory. PURPOSE OF THE STUDY: This study used Rasch analysis to examine the content, scoring and measurement properties of the PRWHE. METHODS: PRWHE scores (n = 264) from persons with a traumatic injury or reconstructive surgery to one hand were collected from an outpatient hand rehabilitation facility. Rasch analysis was conducted to assess how the PRWHE fit the Rasch model, confirms the scaling structure of the pain and disability subscales, and identifies any areas of bias from differential item functioning. RESULTS: Rasch analysis of the PRWHE supports internal consistency of the scale (α = 0.96) and reliability (as measured by the person separation index) of 0.95. While gender, age, diagnosis, and duration since injury all systematically influenced how people scored the PRWHE, hand dominance and affected side did not. Rasch analysis supported a 3 subscale structure (pain, specific activities and usual activities) rather than the current divisions of pain and disability. CONCLUSIONS: Initial examination of the PRWHE indicates the psychometric properties of consistency, reliability and responsiveness previously tested by classical methods are further supported by Rasch analysis. It also suggests the scale structure may be best considered as 3 subscales rather than simply pain and disability.