Development and initial evaluation of the psychometric properties of self-efficacy and adherence scales for patients with a left ventricular assist device

Context-No tools exist to measure patients' self-efficacy for and adherence to the complex home-care regimen after having a left ventricular device (LVAD) implanted. Objective-To develop 2 new instruments, the LVAD Patient Self-Efficacy Scale (LPSES) and the LVAD Patient Home Management Adherence Scale (LPHMAS), and evaluate their psychometric properties. Methods-This multistage instrumentation study recruited 102 patients (77.5% men and 22.5% women) aged 20 to 82 years, predominantly from the Midwest (34.3%) and the Northeast (26.5%) regions of the United States. Main indications for LVAD were bridge-to-transplant (69.6%) and destination therapy (21.6%), with mean implant duration of 19.9 (SD, 15.5) months. Study participants completed the following instruments: LPSES, LPHMAS, General Self-Efficacy Scale (GSES), Medical Outcomes Study General Adherence (MOSGA), and Self-Care Heart Failure Index (SCHFI)confidence and maintenance subscales. Item analyses, psychometric properties including factorial and convergent validities, and internal consistency reliability were tested. Results-Factor analyses showed that the variances for the 20-item LPSES and 9-item LPHMAS were 60.2% and 53.6%, respectively. Convergent validity of the newly developed instruments was supported by the following correlations: LPSES and GSES (r = 0.34); LPSES and SCHFI-confidence (r = 0.60); LPHMAS and MOSGA (r = 0.33); LPHMAS and SCHFI-maintenance (r = 0.40). Internal consistency reliability coefficients were 0.94 (LPSES) and 0.84 (LPHMAS). Based on these data, the LPSES and LPHMAS are valid and reliable measures of self-efficacy and adherence specific for LVAD patients. Confirmatory testing is needed to further support the validity of these instruments for use in research and clinical practice.