Association Between Having a Physician as a Usual Source of Care and Self-Reported Adherence to Antihypertensive Medication

Using annual data from the Korea Health Panel Survey, this study examined the association between having a physician as a usual source of care and self-reported antihypertensive medication adherence, while also considering health literacy as a patient-level factor. Respondents who reported no major chronic conditions other than hypertension in the 2021 chronic disease module formed the baseline cohort, and their 2021-2023 data were linked to create repeated person-year observations. Using generalized estimating equations, multivariable logistic regression models were fitted to 1,091 person-year observations from 414 individuals, with medication adherence specified as a binary outcome. Sensitivity analyses used a balanced 2021-2023 panel and an expanded 2019-2023 dataset. Having a physician as a usual source of care was positively associated with medication adherence (OR=1.617, 95% CI 1.23-2.13, p=0.001), whereas health literacy was not significantly associated with adherence (OR=1.022, 95% CI 0.72-1.44, p=0.902). This association was generally consistent across sensitivity analyses. These findings indicate that having a physician as a usual source of care is associated with higher self-reported antihypertensive medication adherence. Further research is needed to clarify the roles of care continuity and the quality of the patient-physician relationship in this association.