title: Health insurance status, cost-related medication underuse, and outcomes among diabetes patients in three systems of care.
abstract: BACKGROUND
  Chronically ill patients often experience difficulty paying for their medications and, as a result, use less than prescribed.
  
  
  OBJECTIVE
  The objectives of this study were to determine the relationship between patients with diabetes' health insurance coverage and cost-related medication underuse, the association between cost-related underuse and health outcomes, and the role of comorbidity in this process.
  
  
  METHODS
  We used a patient survey with linkage to insurance information and hemoglobin A1C (A1C) test results.
  
  
  METHODS
  We studied 766 adults with diabetes recruited from 3 Veterans Affairs (VA), 1 county, and 1 university healthcare system.
  
  
  RESULTS
  Main outcomes consisted of self-reported medication underuse as a result of cost, A1C levels, symptom burden, and Medical Outcomes Study 12-Item Short-Form physical and mental functioning scores.
  
  
  RESULTS
  Fewer VA patients reported cost-related medication underuse (9%) than patients with private insurance (18%), Medicare (25%), Medicaid (31%), or no health insurance (40%; P <0.0001). Underuse was substantially more common among patients with multiple comorbid chronic illnesses, except those who used VA care. The risk of cost-related underuse for patients with 3+ comorbidities was 2.8 times as high among privately insured patients as VA patients (95% confidence interval, 1.2-6.5), and 4.3 to 8.3 times as high among patients with Medicare, Medicaid, or no insurance. Individuals reporting cost-related medication underuse had A1C levels that were substantially higher than other patients (P <0.0001), more symptoms, and poorer physical and mental functioning (all P <0.05).
  
  
  CONCLUSIONS
  Many patients with diabetes use less of their medication than prescribed because of the cost, and those reporting cost-related adherence problems have poorer health. Cost-related adherence problems are especially common among patients with diabetes with comorbid diseases, although the VA's drug coverage may protect patients from this increased risk.
authors.affiliation: Center for Practice Management and Outcomes Research, VA Ann Arbor Health Care System, Ann Arbor, Michigan 48113-0170, USA. jpiette@umich.edu
authors.forename: John D
authors.initials: JD
authors.lastname: Piette
authors.forename: Todd H
authors.initials: TH
authors.lastname: Wagner
authors.forename: Michael B
authors.initials: MB
authors.lastname: Potter
authors.forename: Dean
authors.initials: D
authors.lastname: Schillinger
mesh_terms: D000368:Aged; D017281:Cost of Illness; D003920:Diabetes Mellitus / Q000188:drug therapy* / Q000191:economics*; D017723:Drug Utilization Review; D005252:Fees, Pharmaceutical / Q000706:statistics & numerical data*; D005260:Female; D019538:Health Care Surveys; D006787:Hospitals, Veterans / Q000191:economics / Q000706:statistics & numerical data*; D006801:Humans; D019458:Insurance Coverage / Q000191:economics* / Q000706:statistics & numerical data; D007348:Insurance, Health / Q000191:economics* / Q000706:statistics & numerical data; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D017063:Outcome Assessment, Health Care; D010349:Patient Compliance / Q000706:statistics & numerical data; D012959:Socioeconomic Factors; D014481:United States; D014493:United States Department of Veterans Affairs