title: The effects of health plan copayments on adherence to oral diabetes medication and health resource utilization.
abstract: OBJECTIVE
  To assess the effects of copayments on oral diabetes medication adherence, health resource utilization, and expenditure.
  
  
  METHODS
  Retrospective, observational analysis of medical and pharmacy claims data from PPG Industries employees, retirees, and dependents (2003-2005). Average monthly copayments were stratified low (US$0-9), medium (US$10-19), or high (US$20+).
  
  
  RESULTS
  In 2052 individuals, adherence to oral diabetes medication was highest for the low copayment group for both age groups >or=65 years; 84% low, 77% medium, 64% high (P < 0.0001) and <65 years; 74% low, 71% medium, 55% high (P < 0.0001). For patients <65 years, total health care expenditure was 22% lower in the low versus high copayment group (P = 0.024), resulting in average savings of US $3116 per patient per year. Risk of hospitalization was significantly lower in the low versus the high copayment group for patients >or=65 years of age.
  
  
  CONCLUSIONS
  High copayments were associated with lower adherence to oral diabetes medications for all patients and higher total health care costs for patients less than 65.
authors.affiliation: PPG Industries, Pittsburgh, PA 15272, USA. colombi@ppg.com
authors.forename: Alberto M
authors.initials: AM
authors.lastname: Colombi
authors.forename: Kristina
authors.initials: K
authors.lastname: Yu-Isenberg
authors.forename: Julie
authors.initials: J
authors.lastname: Priest
mesh_terms: D000284:Administration, Oral; D017677:Age Distribution; D000368:Aged; D003669:Deductibles and Coinsurance / Q000191:economics* / Q000706:statistics & numerical data; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy / Q000191:economics*; D003955:Diagnostic Tests, Routine / Q000191:economics / Q000706:statistics & numerical data; D005252:Fees, Pharmaceutical; D005260:Female; D005382:Financing, Personal / Q000145:classification / Q000191:economics* / Q000706:statistics & numerical data*; D005102:Health Expenditures; D006295:Health Resources / Q000706:statistics & numerical data; D006801:Humans; D007004:Hypoglycemic Agents / Q000191:economics* / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D010349:Patient Compliance / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D014481:United States
chemical_list: D007004:Hypoglycemic Agents