A psychometric evaluation of the four-item version of the Control Attitudes Scale for patients with cardiac disease and their partners

BACKGROUND: The four-item Control Attitudes Scale (CAS) was developed to measure control perceived by patients with cardiac disease and their family members, but extensive psychometric evaluation has not been performed. OBJECTIVE: The aim was to translate, culturally adapt and psychometrically evaluate the CAS in a Swedish sample of implantable cardioverter defibrillator (ICD) recipients, heart failure (HF) patients and their partners. METHODS: A sample (n=391) of ICD recipients, HF patients and partners were used. Descriptive statistics, item-total and inter-item correlations, exploratory factor analysis, ordinal regression modelling and Cronbach's alpha were used to validate the CAS. RESULTS: The findings from the factor analyses revealed that the CAS is a multidimensional scale including two factors, Control and Helplessness. The internal consistency was satisfactory for all scales (α=0.74-0.85), except the family version total scale (α=0.62). No differential item functioning was detected which implies that the CAS can be used to make invariant comparisons between groups of different age and sex. CONCLUSIONS: The psychometric properties, together with the simple and short format of the CAS, make it to a useful tool for measuring perceived control among patients with cardiac diseases and their family members. When using the CAS, subscale scores should be preferred.