JHT READ FOR CREDIT ARTICLE #270. Scientific/Clinical Article Measurement properties of the Patient-Rated Wrist and Hand Evaluation: Rasch analysis of responses from a traumatic hand injury population Tara Packham OT(Reg)Ont, MSc a, b, c, * , Joy C. MacDermid PT, PhD a, b a McMaster University, School of Rehabilitation Science, Hamilton, Ontario, Canada b McMaster Hand, Arm and Nerve (MacHANd) Research Network, McMaster University, Hamilton, Ontario, Canada c Hamilton Health Sciences, Neurosciences and Trauma Program, Hamilton, Ontario, Canada article info Article history: Received 26 August 2012 Received in revised form 17 December 2012 Accepted 26 December 2012 Available online 3 April 2013 Keywords: Rasch analysis Hand injuries Self-reported outcomes Patient-Rated Wrist and Hand Evaluation abstract 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 ¼ 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 (a ¼ 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. Ó 2013 Hanley & Belfus, an imprint of Elsevier Inc. All rights reserved. Introduction and background The Patient-Rated Wrist and Hand Evaluation (PRWHE) is a 15 item self-report questionnaire about pain and disability evolving from the Patient-Rated Wrist Evaluation, a measure originally developed for measuring outcomes in persons following distal radius fracture. 1,2 MacDermid and Tottenham commenced valida- tion of this revised tool with persons attending therapy after traumatic wrist and hand injuries by comparing it to the Disabilities of the Arm, Shoulder and Hand (DASH), and evaluating the responsiveness of both assessments. 2 Subsequent psychometric evaluations of this tool for hand populations include validation of the PRWHE with persons with osteoarthritis (OA) of the thumb carpo-metacarpal joint (CMC) 3 and translation and retesting of a Dutch language version (PRWHE-DLV). 4 Classical test theory vs. Rasch analysis The psychometric concepts of reliability and validity are often appraised within the framework of classical test theory (CTT). Evaluation within this framework is based on assumptions that include: 1) the more items in the test or scale, the less it will be influenced by random error, 2) reliability and validity estimates apply only to the sample studied, or other populations well rep- resented by the sample, and 3) any changes to the scale will require complete re-evaluation of the scale characteristics. 5 However, this paradigm does not address the potential for systematic biases such as the gender of the respondents to influence how they answer the questions on an assessment. * Corresponding author. Hand Therapy Clinic, Hamilton Health Sciences e General Site, 237 Barton St. East, Hamilton, Ontario, Canada L8L 2X2. Tel.: þ1 905 527 4322x46296; fax: þ1 905 527 0338. E-mail addresses: packhamt@gmail.com, packhamt@hhsc.ca (T. Packham). Contents lists available at SciVerse ScienceDirect Journal of Hand Therapy journal homepage: www.jhandtherapy.org 0894-1130/$ e see front matter Ó 2013 Hanley & Belfus, an imprint of Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jht.2012.12.006 Journal of Hand Therapy 26 (2013) 216e224