The mediating role of trust in physicians on the association between multidimensional health literacy and medication adherence in hemodialysis: A cross-sectional study

Rationale & Objective Basic health literacy (HL) and trust in physicians can influence medication adherence (MA) in dialysis patients. However, how high-order HL is associated with MA, and how trust in physicians mediates this association remain unclear. We assessed the interrelationships between HL, trust in physicians, and MA, and investigated the mediating role of trust in physicians in the relationship between HL and MA. Study Design Multicenter cross-sectional study. Setting & Participants Japanese adults receiving outpatient hemodialysis at six dialysis centers. Exposures Multidimensional HL 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. Outcome MA was measured using the 12-item Adherence Starts Knowledge (ASK-12) scale. Analytical Approach A series of general linear models was created to analyze the associations between HL and ASK-12 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 HL were associated with lower barriers to MA (per 1-point increase: -1.90 (95% confidence interval (CI): -2.67, -1.13) and -2.11 (95% CI: -3.35, -0.87), respectively), whereas higher critical HL was associated with higher barriers (per 1-point increase: 1.67 (95% CI: 0.43, 2.90)). After controlling for trust in physicians, the magnitude of the association between HLs and MA decreased. Trust in physicians partially mediated the association between functional or communicative HL and MA (especially “beliefs”) and completely mediated the association between critical HL and MA (especially “behaviors”). Limitation Possible reverse causation. Conclusions In addition to functional HL, communicative and critical HL were associated with MA, and their associations were mediated by trust in physicians. To effectively improve MA, individualized strategies for each HL and favorable physician–patient interactions are important. ### Competing Interest Statement RI received payments for speaking from Astellas Pharma, Inc., Novartis Pharma K.K., and Otsuka Pharmaceuticals. T. Toida received consulting fees from Astellas Pharma Inc., and payments and educational events from Torii Pharmaceutical Co., Ltd., Ono Pharmaceutical Co., Ltd., Kyowa Kirin Co., Ltd., AstraZeneca K.K., and Nobelpharma Co., Ltd. T. Toishi received payment for speaking and educational events from Otsuka Pharmaceuticals. MM received payments for speaking and educational events from Astellas Pharma Inc. and Baxter Co., Ltd. TS has received payment for speaking and educational events from Astellas Pharma Inc, AstraZeneca K.K, Baxter Co., Ltd., Bayer Yakuhin., Ltd., Bristol-Myers Squibb Co., CureApp, Inc., Chugai Pharmaceutical Co., Ltd., Daiichi Sankyo Co., Ltd., Eli Lilly Japan K.K., Janssen Pharmaceutical K.K, Kaneka Medix Corp, Kissei Pharmaceutical Co., Ltd., Kowa Co., Ltd., Kyowa Kirin Co., Ltd, Mochida Pharmaceutical Co., Ltd., Nobelpharma Co., Ltd, Novartis Pharma K.K., Novo Nordisk Pharma., Ltd., Ono Pharmaceutical Co., Ltd., Otsuka Pharmaceutical, Terumo Corp, and Torii Pharmaceutical Co., Ltd. NK received grants from the Japan Society for the Promotion of Science, consulting fees from GlaxoSmithKline K.K., and payments for speaking and educational events from Taisho Pharmaceutical Co. Ltd. and Eisai Co. Ltd. ### Funding Statement This study was supported by JSPS KAKENHI (grant numbers: JP19KT0021 and JP23K16271). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: This study adhered to the Declaration of Helsinki and was approved by the Ethical Review Board of Fukushima Medical University (number: ippan2021-292). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present work are contained in the manuscript.