Evaluation of the psychometric properties of self-efficacy and adherence scales for caregivers of patients with a left ventricular assist device

Context-No published instrument has been designed to measure caregivers' self-efficacy for and adherence to the complex home-care regimen of patients with a left ventricular assist device (LVAD). Objective-To evaluate the psychometric properties of 2 newly developed instruments: the LVAD Caregiver Self-Efficacy Scale (LCSS) and the LVAD Caregiver Home Management Adherence Scale (LCAS). Methods-A multistage design was employed for this instrumentation study. Of the 125 LVAD caregivers recruited from online support groups, 98 (78.4%) provided complete data. Participants were predominantly female (80%), aged 18 to 79 years, from 4 regions of the United States. They completed the following instruments: LCSS, LCAS, General Self-Efficacy Scale (GSE), and the confidence and maintenance subscales of the Caregiver Contribution to Self-Care of Heart Failure Index (CC-SCHFI). Item analyses, factorial construct validity, convergent validity, and internal consistency reliability of the scales were evaluated. Results-The analysis of the LCSS (21 items) revealed a 2-factor solution, which consisted of a 17-item routine factor and a 4-item anticipatory factor. Convergent validity of the LCSS was supported by moderate correlations among LCSS, GSE, and CC-SCHFI-confidence. The analysis of LCAS (17 items) revealed a 1-factor solution. Its convergent validity was supported by moderate correlation between LCAS and CC-SCHFI-maintenance. Internal consistency reliability coefficients of the LCSS and LCAS were α = 0.93 and α = 0.96, respectively. These data suggest that the 2 instruments are adequately valid and reliable measures of self-efficacy and adherence in the context of LVAD patient care managed by home caregivers. Further research is needed to support the applicability of these instruments in other research and practice settings.