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

Abstract

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. 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. 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. 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.