The impact of medication adherence on health outcomes for chronic metabolic diseases: A retrospective cohort study

Background: Hypertension, diabetes, and hyperlipidemia have a large influence on health outcomes due to their chronic nature and serious complications. Medication is a key factor in preventing disease advancement, and it is important to assess whether good medication adherence has any potential long-term impact on health outcomes and provides an international validation on the relationship. Objectives: To evaluate the impact of good medication adherence on health outcomes of complications and hospitalizations for hypertension, hyperlipidemia, and diabetes. Methods: Patients who had had outpatient pharmacy claims for drugs for hypertension, diabetes, or hyperlipidemia were separately identified from the Korean National Health Insurance Claims Database in year 2009. A 10% random sample was respectively drawn from the three disease groups, and all claims from years 2008-2011 were extracted for the sampled subjects. Medication adherence was measured by the medication possession ratio (MPR) during the 12-month after the index date, the initial date from when medication was counted, with poor adherence as <80% of MPR. Health outcomes were measured both at 2 and 3 years after the index date as any occurrence of disease-related complications, disease-specific hospitalizations, and all-cause hospitalizations. Results: Poor medication adherence was associated with a higher occurrence of disease-specific hospitalizations for hypertension patients (+10.9%, only at 2 years). The likelihood of all-cause hospitalization was higher among patients who had poor medication adherence in hypertension (+32% and +29% at 2 and 3 years), hyperlipidemia (+16% and +14% at 2 and 3 years), and diabetes (+32% and +29% at 2 and 3 years). Poor medication adherence also increased the likelihood of complications for hypertension (+14% and +7% at 2 and 3 years) and hyperlipidemia patients (+8.1% at 2 years). Conclusions: Targeting good medication adherence could be a valuable policy strategy to effectively manage chronic diseases to improve health outcomes. (C) 2014 Elsevier Inc. All rights reserved.