Clinical and economic outcomes in medication-adherent and -nonadherent patients with type 2 diabetes mellitus in the republic of Korea

Background The prevalence and social burden of type 2 diabetes mellitus (T2DM) is increasing. Medication adherence is necessary for positive outcomes in patients with T2DM. Objective This study evaluated the association between medication adherence and clinical/economic outcomes in patients with T2DM in the Republic of Korea over a 3-year period. Methods This study used data from the Korean National Diabetes Program at 5 hospitals. Medication possession ratios of ≥90% and <90% were used to define adherent and nonadherent groups, respectively. The degree of glycemic control, changes in blood pressure and lipid profiles, and health care costs were compared. Results Of the 608 patients, 472 were medication adherent and 136 were nonadherent. The adherent patients displayed improved fasting blood glucose and hemoglobin A_1c during the study. Diastolic blood pressure and total cholesterol were lower at 36 months, and lower low-density lipoprotein cholesterol was noted at baseline and 24 months. The total health care costs were $1861, $2060, and $1924, respectively, versus $1617, $1751, and $1602 during the 3-year study period for the adherent group versus the nonadherent group, respectively (P = 0.316, 0.627, and 0.172, respectively), whereas the outpatient drug costs were $1143, $1176, and $1162 in the adherent group versus $925, $778, and $914 in the nonadherent group (P = 0.002, P < 0.001, and P = 0.001). Conclusions The adherent patients displayed better glycemic control and lipid profiles. Medication-related expenses were higher in the adherent group, but overall health care costs, including hospitalization costs, were similar between the 2 groups.