This study examined medication adherence by considering not only the components of self-efficacy (efficacy expectation and outcome expectation), but also both subjective health literacy( HL) and the objective HL measure, health numeracy( HN). The target diseases included hypertension, diabetes mellitus, and dyslipidemia, which are representative chronic conditions without subjective symptoms, as well as hay fever and insomnia, which are symptomatic conditions with increasing patient numbers( without overlapping diseases). Through an online survey, patients with these conditions were asked about their medication adherence, efficacy expectation, outcome expectation, three dimensions of HL( functional, interactive, and critical), and two types of HN( NVS-J and Lipkus-J). The results of multiple population analyses via path analysis showed that, for adherence, self-efficacy’s efficacy
expectation and outcome expectation were independent factors, without mediation by HL. In addition, for symptomatic diseases, only the outcome expectation of self-efficacy affected adherence. Of the HL dimensions, functional HL affected all diseases, whereas critical HL negatively affected some diseases. These findings suggest that the influence structure of self-efficacy varies based on the presence of symptoms, indicating that fostering efficacy expectations is crucial for asymptomatic diseases, whereas fostering outcome expectations is vital for symptomatic diseases. Furthermore, functional HL is useful in predicting medication adherence, and for some diseases, it is important to consider the potential overestimation of medication risks.
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