The Control Attitudes Scale-Revised: psychometric evaluation in three groups of patients with cardiac illness.

BACKGROUND: Perceived control is a construct with important theoretical and clinical implications for healthcare providers, yet practical application of the construct in research and clinical practice awaits development of an easily administered instrument to measure perceived control with evidence of reliability and validity.
OBJECTIVE: To test the psychometric properties of the Control Attitudes Scale-Revised (CAS-R) using a sample of 3,396 individuals with coronary heart disease, 513 patients with acute myocardial infarction, and 146 patients with heart failure.
METHODS: Analyses were done separately in each patient group. Reliability was assessed using Cronbach's alpha to determine internal consistency, and item homogeneity was assessed using item-total and interitem correlations. Validity was examined using principal component analysis and testing hypotheses about known associations.
RESULTS: Cronbach's alpha values for the CAS-R in patients with coronary heart disease, acute myocardial infarction, and heart failure were all greater than .70. Item-total and interitem correlation coefficients for all items were acceptable in the groups. In factor analyses, the same single factor was extracted in all groups, and all items were loaded moderately or strongly to the factor in each group. As hypothesized in the final construct validity test, in all groups, patients with higher levels of perceived control had less depression and less anxiety compared with those of patients who had lower levels of perceived control.
CONCLUSION: This study provides evidence of the reliability and validity of the 8-item CAS-R as a measure of perceived control in patients with cardiac illness and provides important insight into a key patient construct.