Relationships between health literacy, self-efficacy, and medication adherence in older people with polypharmacy: A cross-sectional study

Purpose: This study identified the relationships between health literacy, self-efficacy, and medication adherence among older people with polypharmacy and analyzed the factors affecting medication adherence. Methods: This was a cross-sectional study using a survey of 95 participants who were on five or more drugs, 65 years or older, and visited one community center in Seoul between August 5, 2019 and August 7, 2019. Data were collected using a questionnaire and analyzed with descriptive statistics, t-test, ANOVA, Tukey test, Pearson's correlation coefficient, and multiple regression via the IBM SPSS 23.0 program. Results: The participants took on average 8.32±3.90 drugs daily. Their health literacy was very low at 3.53±2.07. Self-efficacy and medication adherence were high at 33.63±5.36 and 15.03±3.27, respectively. Health literacy differed based on age and education levels, whereas self-efficacy differed depending on the frequency of medication. No demographic or medication-related factors caused a difference in medication adherence. Health literacy did not correlate with self-efficacy and medication adherence. Self-efficacy showed a negative correlation with medication adherence (r=-.52, p<.001). However, as a lower medication adherence score indicates greater adherence, a negative correlation means higher self-efficacy is linked with better adherence. Self-efficacy influenced medication adherence (β=-0.52, p<.001) with an explanatory power of 27.0% (F=17.01, p<.001) in this group. Also, the negative regression coefficient means higher self-efficacy was associated with better adherence. Conclusion: Medication adherence was generally high, with self-efficacy being the main influencing factor. Hence, intervention programs that promote self-efficacy should be implemented for older people with polypharmacy.