Trust, Multidimensional Health Literacy, and Medication Adherence among Patients Undergoing Long-Term Hemodialysis

Abstract

Background Basic health literacy and trust in physicians can influence medication adherence in patients receiving dialysis. However, how high-order health literacy is associated with medication adherence and how trust in physicians mediates this association remain unclear. We assessed the inter-relationships between health literacy, trust in physicians, and medication adherence. We investigated the mediating role of trust in physicians in the relationship between health literacy and medication adherence. Methods This multicenter cross-sectional study included Japanese adults receiving outpatient hemodialysis at six dialysis centers. Multidimensional health literacy was measured using the 14-item Functional, Communicative, and Critical Health Literacy scale. Trust in physicians was measured using the five-item Wake Forest Physician Trust scale. Medication adherence was measured using the 12-item Adherence Starts with Knowledge scale. A series of general linear models were created to analyze the associations between health literacy and Adherence Starts Knowledge scores with and without trust in physicians. Mediation analysis was performed to determine whether trust in physicians mediated this association. Results In total, 455 patients were analyzed. Higher functional and communicative health literacies were associated with less adherence difficulties (per 1-point higher: −1.79 [95% confidence interval (CI): −2.59 to −0.99] and −2.21 [95% CI: −3.45 to −0.96], respectively), whereas higher critical health literacy was associated with greater adherence difficulties (per 1-point higher: 1.69 [95% CI: 0.44 to 2.94]). After controlling for trust in physicians, the magnitude of the association between health literacies and medication adherence decreased. Trust in physicians partially mediated the association between functional or communicative health literacy and medication adherence (especially beliefs) and completely mediated the association between critical health literacy and medication adherence (especially behaviors). Conclusions Functional and communicative health literacies were positively associated with medication adherence, whereas critical health literacy was negatively associated with it. Each association was mediated by trust in physicians.