title: The impact of medication adherence on health outcomes for chronic metabolic diseases: a retrospective cohort study.
abstract: 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.
  
  
  OBJECTIVE
  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.
authors.affiliation: College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon, South Korea.
authors.forename: Euna
authors.initials: E
authors.lastname: Han
authors.affiliation: College of Pharmacy, Chung-Ang University, Seoul, South Korea.
authors.forename: Dong-Churl
authors.initials: DC
authors.lastname: Suh
authors.affiliation: College of Pharmacy, Chung-Ang University, Seoul, South Korea.
authors.forename: Seung-Mi
authors.initials: SM
authors.lastname: Lee
authors.affiliation: College of Pharmacy, Gachon University, Incheon, South Korea. Electronic address: smjang@gachon.ac.kr.
authors.forename: Sunmee
authors.initials: S
authors.lastname: Jang
mesh_terms: D000328:Adult; D000368:Aged; D048909:Diabetes Complications / Q000453:epidemiology; D003920:Diabetes Mellitus / Q000188:drug therapy* / Q000453:epidemiology; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D006949:Hyperlipidemias / Q000188:drug therapy* / Q000453:epidemiology; D006973:Hypertension / Q000150:complications / Q000188:drug therapy* / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D056910:Republic of Korea / Q000453:epidemiology; D012189:Retrospective Studies; D016896:Treatment Outcome; D016903:Drug Monitoring
keywords: Diabetes; Health outcomes; Hyperlipidemia; Hypertension; Medication adherence; National health insurance claims data; South Korea