RESUMO
OBJECTIVE: Computer adaptive tests (CATs) offer a flexible, test fair, and economic opportunity for accurate measurement of anxiety in patients with cardiovascular diseases (CVDs). The objective of this study was to develop and calibrate an item bank [anxiety item bank for cardiovascular patients (AIB-cardio)] as a prerequisite for an anxiety-CAT in CVD patients. STUDY DESIGN AND SETTING: After pretesting for relevance and comprehension, a pool of 155 anxiety items was answered on a five-point Likert scale. Sample consisted of 715 CVD patients, who were recruited in 14 German cardiac rehabilitation centers. A confirmatory factor analysis (CFA), Mokken analysis, and Rasch analysis were conducted. RESULTS: The results of CFA and Mokken analysis confirmed one factor structure and double monotonicity. In Rasch analysis, merging response categories and removing items with misfit, differential item functioning or local response dependency reduced the AIB-cardio to 37 items. The AIB-cardio fitted to the Rasch model with a nonsignificant item-trait interaction (chi-square, 133.89; degrees of freedom, 111; P = 0.07). Person separation reliability was 0.85, and unidimensionality could be verified. CONCLUSION: The calibrated, unidimensional AIB-cardio provides the basis for a CAT to assess anxiety in rehabilitation patients with CVD with good psychometric properties. Further testing in other cardiovascular patients is needed to increase generalizability.
