Reliability, validity and factor structure of the Appraisal of Self-Care Agency Scale-Revised (ASAS-R)

Self-care agency is a fundamental concept in nursing and health care research. Having self-care agency enhances an individual's health-promoting behaviours and/or specific capabilities for chronic disease self-management. The purpose of this study was to continue the development and psychometric testing of the Appraisal of Self-Care Agency - Revised (ASAS-R).

A cross-sectional methodological design was used to examine the reliability, validity and factor structure of the ASAS-R among individuals from the general population. The sample consisted of 629 adults who were randomly selected to conduct an exploratory factor analysis (EFA; n=240) and a confirmatory factor analysis (CFA; n=389) of the scale. A demographic questionnaire, the ASAS-R and the Health-Promoting Lifestyle Profile (HPLP-II) were the measures used to collect the data.

The final 15-item three-factor ASAS-R had an overall Cronbach's alpha (α) of 0.89. The three factors extracted, rotated and scored in this study were labelled: having power for self-care, developing power for self-care and lacking power for self-care. All inter-items and item-to-total correlations met recommended criteria of r=0.30 to r=0.70, except for one of the items that had an item-to-total correlation of 0.71, slightly exceeding the maximum recommended item-to-total correlation. The three factors had Cronbach's alphas of 0.86, 0.83 and 0.79, respectively. The three factors together explained 61.7% of the scale items variance. Each item of the scale had a strong factor loading ranging from 0.52 to 0.81. All measures of model fit exceeded the recommended criteria, indicating that the 15-item ASAS-R had a very good fit (χ(2) /d.f.=1.97, GFI=0.94, AGFI=0.92, CFI=0.96, TLI=0.95, RMSEA=0.05, RMR=0.05 and the PCLOSE=0.48).

The 15-item three-factor ASAS-R is a short, reliable and valid instrument to measure self-care agency among individuals from the general population, but further psychometric evaluation is needed among individuals with chronic diseases, especially those with diabetes mellitus.