Establishing a Cut Point for the Control Attitudes Scale-Revised in an International Sample of Patients With Cardiac Disease.

Abstract

Background: Perceived control is a construct relevant to emotional and clinical outcomes among individuals with chronic illnesses. We previously demonstrated the reliability and validity of the Control Attitudes Scale-Revised (CAS-R), and it has been used extensively in research to measure perceived control. Yet, there is a gap in interpretation of CAS-R scores. A standardized cut point has not yet been established to facilitate classification of patients into distinct high- and low-perceived control categories. Identifying this cut-off point will be of significant value to clinicians and researchers.

Objectives: To identify an evidence-based cut point for the CAS-R to define lower and higher levels of perceived control among patients with a variety of cardiac diagnoses.

Methods: In this psychometric secondary analysis, we used data from patients with heart failure or coronary heart disease, which included 4,555 patients from three countries. Data were collected on perceived control, depression and/or anxiety, and/or cardiac events (cardiac hospitalization and cardiac death). We used receiver operating characteristic (ROC) curves and area under the ROC area under the curve (AUC) to test the accuracy of using the CAS-R scores to separate the patients into anxious or non-anxious groups and depressed or non-depressed groups. Kaplan-Meier plots with log-rank tests and Cox-survival analyses were used to compare cardiac event-free survival outcomes between higher and lower perceived control groups.

Results: Two possible cut points were identified using ROC curves and AUC. Cut points were identified using anxiety or depression as the state variable and CAS-R scores as the test variable. Using Kaplan-Meier analyses and log-rank tests, we determined that 29 was the cut point that demonstrated patients in the higher CAS-R group had significantly better cardiac event-free survival than those in the lower CAS-R group. Using the cut point of 30, the differences in cardiac event-free survival between groups did not reach a significant level.

Discussion: Identifying a CAS-R cut point enhances the practical application of the CAS-R and makes it a valuable instrument for assessing the effect of targeted interventions among cardiac patients with lower perceived control.