Assessment of a medication management program targeting hypertension and diabetes patients: Impact on medication adherence

Background: The National Health Insurance Service in South Korea has conducted a telephone outreach program to improve medication adherence for hypertension and diabetes patients since 2014. Objectives: To evaluate the direct outcomes of the program. Methods: Patients were identified among those who visited an outpatient clinic at least twice or used an inpatient service at least once for hypertension or diabetes during 6-month intervals and who were nonadherent based on the proportion of days covered (PDC) calculated. As a preliminary intervention, participants were mailed an information leaflet on their own medication adherence and other tips for effective self-management of chronic diseases. For the intervention, two phone calls and three phone messages were made to patients by 24 participating regional offices. Ultimately, 2,428 hypertension patients and 884 diabetes patients received the intervention. Propensity matching was used based on age, sex, and the Charlson Comorbidity Index to select 12,140 hypertension and 4,420 diabetes patients as controls in the non-participating regions. The outcome was PDC. Multivariate ordinary least squares or logistic regression analysis were used with difference-in-difference specification. Results: The adjusted quarterly PDC increased by 1.96%p for hypertension (p = 0.023) and by 7.79%p for diabetes patients (p < 0.001). Approximately 40.6% and 51.7% of hypertension and diabetes patients in the treatment arm (p = 0.0069) became adherent after the intervention, whereas the corresponding proportions were 37.7% and 41.4% (p < 0.001) in the control group. Both treatment groups showed a higher likelihood of good medication adherence (hypertension: odds ratio = 1.157, 95% CI [1.058, 1.265]; diabetes: odds ratio = 1.532, 95% CI [1.323, 1.774]). The control group, who received only a print intervention with a mailed leaflet, also showed a dramatic increase in medication adherence. Conclusions: An insurer-coordinated telephone-administered program resulted in improvement of medication adherence among patients with hypertension and diabetes.