Association between medical complications according to continuity of care and medication adherence in patients with hypertension in Korea: a national population-based cohort study

OBJECTIVES: To analyse the differences in hypertensive complications according to continuity of care (COC) and medication adherence in patients with hypertension. DESIGN: A national population-based retrospective cohort study. SETTING: Secondary data analysis using National insurance claims data at all levels of hospitals in South Korea. PARTICIPANTS: A total of 102 519 patients diagnosed with hypertension were included in this study. PRIMARY OUTCOME MEASURES: The levels of COC and medication adherence were estimated within the initial 2 years of the follow-up period, and the incidence of medical complications was estimated within the subsequent 16 years. We used the level of COC to measure COC and the medication possession ratio (MPR) to measure medication adherence. RESULTS: The average level of COC in the hypertension group was 0.8112. The average proportion of the MPR in the hypertension group was 73.3%. COC in patients with hypertension showed varying results: the low COC group had a 1.14-fold increased risk of medical complications compared with the high COC group. In terms of the level of MPR in patients with hypertension, the 0%–19% MPR group had a 1.5-fold risk of medical complications relative to the 80%–100% MPR group. CONCLUSIONS: In patients with hypertension, high COC and medication adherence for the first 2 years of diagnosis can help prevent medical complications and promote patients’ health. Therefore, effective strategies to improve COC and medication adherence are required. Future research should include some factors that may affect the incidence of hypertensive complications, such as familial aggregation, and hazard stratification by the level of blood pressure, which were not considered in this study. Therefore, there may be residual confounding and still room for improvement.