The reliability of the Communication Disability Profile: A patient-reported outcome measure for aphasia

Abstract

Background: The use of patient-reported outcome (PRO) measures is important for understanding the impact of aphasia from the perspective of the person with aphasia. However, communication difficulties may make it challenging for people with aphasia to self-report. The Communication Disability Profile (CDP) (Swinburn & Byng, 2006) is a newly published outcome measure that includes aphasia-friendly design features (e.g., pictures, simple wording, key words in bold, picture-rating scales) to support people with aphasia in self-reporting the impact of aphasia on their lives. Aim: This pilot study aimed to investigate the test–retest reliability and internal consistency of the Activities, Participation, and Emotions sections of the CDP. Methods & Procedures: A total of 16 participants with chronic aphasia of different severities and types were administered the CDP twice with a test–retest interval of approximately 2 weeks. Test–retest reliability was assessed using the Intraclass Correlation Coefficient (ICC) and “Minimal differences (MD) considered to be real”. Internal consistency was assessed using Cronbach's alpha (α) and corrected item–total correlations. Correlation coefficients, visual inspection, feedback, and observations were used to identify factors that may have affected the reliability or usability of the CDP. Outcomes & Results: The Activities section of the CDP demonstrated high test–retest reliability with an ICC of 0.96 and a small MD value. The Participation section also demonstrated acceptable test–retest reliability (ICC = 0.89). In addition, the Activities and Participation sections demonstrated adequate internal consistency with Cronbach's alpha of more than 0.7 and corrected item–total correlations of more than 0.3. The Emotions section of the CDP did not demonstrate an acceptable level of test–retest reliability (ICC = 0.62) or internal consistency (α < 0.7). Additionally there were no significant relationships between the severity of aphasia or comprehension abilities and the reliability of the CDP. However, increased examiner support may be required for the use of the Emotions section and when using the CDP with people with more severe aphasia. Conclusions: The findings of this study provided preliminary psychometric evidence to support the use of the Activities and Participation sections of the CDP as a PRO measure by people with aphasia.