Development of Rasch-based short screenings for the assessment of treatment motivation in patients with cardiovascular diseases

AbstractPurpose: The aim of the study was to develop unidimensional test-fair and economic short screenings to assess treatment motivation in patients with cardiovascular diseases using the Rasch analysis.Materials and methods: After pretesting for relevance and comprehension, a pool of 132 items on treatment motivation was completed by a sample consisting of 1168 patients with cardiovascular diseases recruited in two German cardiological rehabilitation centers. Confirmatory factor analyses and the Rasch analyses were conducted.Results: The confirmatory factor analyses confirmed a three-factor structure of the treatment motivation construct with task self-efficacy, outcome expectancies and intention as factors. Using the Rasch analysis for each of the three factors and removing items with misfit, differential item functioning and local response dependency reduced the initial item pool to the three short screenings. The short screenings fit to the Rasch model with a root mean square error of approximation ...