title: Clinical outcomes and adherence to medications measured by claims data in patients with diabetes.
abstract: OBJECTIVE
  Although poor medication adherence may contribute to inadequate diabetes control, ways to feasibly measure adherence in routine clinical practice have yet to be established. The present study was conducted to determine whether pharmacy claims-based measures of medication adherence are associated with clinical outcomes in patients with diabetes.
  
  
  METHODS
  The study setting was a large, integrated delivery and financial system serving the residents of southeastern Michigan. The study population consisted of 677 randomly selected patients aged > or =18 years with a diagnosis of diabetes, hypercholesterolemia, and hypertension and who filled at least one prescription for either an antidiabetic, lipid-lowering, or antihypertensive drug in each of the 3 study years (1999-2001). The main outcome measures were HbA1c, LDL cholesterol levels, and blood pressure.
  
  
  RESULTS
  Nonadherent patients had both statistically and clinically worse outcomes than adherent patients. Even after adjusting for demographic and clinical characteristics, nonadherence was significantly associated with HbA1c and LDL cholesterol levels. A 10% increase in nonadherence to metformin and statins was associated with an increase of 0.14% in HbA1c and an increase of 4.9 mg/dl in LDL cholesterol levels. Nonadherence to ACE inhibitors was not significantly associated with blood pressure.
  
  
  CONCLUSIONS
  Claims-based measures of medication adherence are associated with clinical outcomes in patients with diabetes and may therefore prove to be useful in clinical practice. More research is needed on methods to introduce claims-based adherence measurements into routine clinical practice and how to use these measurements to effectively improve adherence and health outcomes in chronic care management.
authors.affiliation: Center for Health Services Research, Henry Ford Health System, One Ford Place, Suite 3A, Detroit, Michigan 48202, USA. mpladev1@hfhs.org
authors.forename: Manel
authors.initials: M
authors.lastname: Pladevall
authors.forename: L Keoki
authors.initials: LK
authors.lastname: Williams
authors.forename: Lisa Ann
authors.initials: LA
authors.lastname: Potts
authors.forename: George
authors.initials: G
authors.lastname: Divine
authors.forename: Hugo
authors.initials: H
authors.lastname: Xi
authors.forename: Jennifer Elston
authors.initials: JE
authors.lastname: Lafata
mesh_terms: D000328:Adult; D000959:Antihypertensive Agents / Q000627:therapeutic use; D003920:Diabetes Mellitus / Q000188:drug therapy* / Q000523:psychology*; D011307:Drug Prescriptions; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use; D000960:Hypolipidemic Agents / Q000627:therapeutic use; D007345:Insurance Claim Review; D008297:Male; D008824:Michigan; D008875:Middle Aged; D010349:Patient Compliance / Q000706:statistics & numerical data*; D016896:Treatment Outcome; D016312:Treatment Refusal / Q000706:statistics & numerical data
chemical_list: D000959:Antihypertensive Agents; D007004:Hypoglycemic Agents; D000960:Hypolipidemic Agents