Cultural adaptation and psychometric testing of The Scenario Test UK for people with aphasia

Abstract

Background: This study explores the psychometric properties of The Scenario Test UK, a culturally adapted version of the Dutch original (The Scenario Test) developed by van der Meulen et al. in 2010, which evaluates functional, daily-life communication in aphasia. The Scenario Test assesses communication in an interactive context with a supportive communication partner.

Aims: To evaluate the reliability (internal consistency, interrater and test-retest reliability) and construct validity (convergent, discriminant and known-groups validity) of The Scenario Test UK.

Methods & procedures: The Scenario Test UK and other language, cognition and praxis assessments were administered to persons with aphasia after stroke (3+ months post-stroke) and to non-aphasic controls. Participants were recruited primarily through community stroke groups. Measures were completed in an interview format. Standard psychometric criteria were used to evaluate reliability and construct validity.

Outcomes & results: A total of 74 participants with aphasia and 20 participants without aphasia took part in The Scenario Test UK. The test showed high levels of reliability. Internal consistency (Cronbach's α = 0.92), interrater reliability (ICC = 0.95) and test-retest reliability (ICC = 0.96) were excellent. Interrater agreement in scores on the individual items ranged from good to excellent (κ = 0.41-1.00) for all but two items (item 4c κ = 0.38, item 6c κ = 0.36). The test demonstrated good levels of convergent (ρ = 0.37-0.75) and discriminant validity (ρ = -0.04 to 0.23). There was strong evidence for known groups validity (U = 132.50, p < .001), with those with aphasia scoring significantly lower [median (interquartile range-IQR) = 47 (39.8-51.0)] than those without aphasia [53 (52-54)].

Conclusions & implications: The data support the reliability and validity of the Scenario Test UK as an assessment of functional, daily-life communication for persons with aphasia. Further testing is needed in independent samples on the measure's psychometric properties, including its sensitivity to change. Pending this testing, The test can be used as an assessment tool to evaluate communication skills with people with aphasia, to guide goal setting for therapy and to measure outcomes in response to therapy.

Keywords: aphasia; functional communication; instrument development; outcome; psychometrics.