The Florida Shock Anxiety Scale (FSAS) for patients with implantable cardioverter defibrillators: testing factor structure, reliability, and validity of a previously established measure

The implantable cardioverter defibrillator (ICD) reduces mortality in patients at risk for life-threatening arrhythmias via high energy shock. The Florida Shock Anxiety Scale (FSAS) was developed to measure ICD patient shock-related anxiety. Initial psychometric evaluation revealed good reliability and validity. The purpose of this study was to examine the psychometrics of the FSAS in a large US sample of ICD patients.

Participants were recruited via e-mail and the survey was completed online. Ultimately, 443 ICD patients (359 male and 421 White) completed the 10-item FSAS.

Means for FSAS were comparable to previously published data (M = 15.18, SD = 6.5). Interitem reliability was good (Cronbach's α= 0.89). The FSAS was negatively correlated with single-item measures of emotional well-being (r =-0.378, P < 0.01), sense of security (r =-0.365, P < 0.01), perceived general health (r =-0.185, P < 0.01), and quality of life (r =-0.216, P < .01), demonstrating discriminant validity. Convergent validity was supported through significant correlations with number of shocks (r = 0.464, P < 0.01) and reported disruptiveness of shock (r = 0.484, P < 0.01). Confirmatory factor analysis revealed that a single (second-order) factor model (χ(2) [34] = 75.34, P < 0.05, comparative fit index = 0.98, root mean-square error of approximation = 0.05) had the best fit.

Shock anxiety as a construct can be measured in a reliable and valid method by the FSAS. These nationally representative data suggest that a single score for shock anxiety is an easy to use and appropriate method of assessment.