title: Cost sharing and adherence to tyrosine kinase inhibitors for patients with chronic myeloid leukemia.
abstract: OBJECTIVE
  The introduction of imatinib, a tyrosine kinase inhibitor (TKI), has greatly increased survival for patients with chronic myeloid leukemia (CML). Conversely, nonadherence to imatinib and other TKIs undoubtedly results in disease progression and treatment resistance. We examined trends in imatinib expenditures from 2002 to 2011 and assessed the association between copayment requirements for imatinib and TKI adherence.
  
  
  METHODS
  We used MarketScan health plan claims from 2002 to 2011 to identify adults (age 18 to 64 years) with CML who initiated imatinib therapy between January 1, 2002, and June 30, 2011, and had insurance coverage for at least 3 months before through 6 months after initiation (N = 1,541). Primary outcomes were TKI discontinuation and nonadherence. The primary independent variable was out-of-pocket cost for a 30-day supply of imatinib. By using a propensity-score weighted sample, we estimated the risk of discontinuation and nonadherence for patients with higher (top quartile) versus lower copayments.
  
  
  RESULTS
  Monthly copayments for imatinib averaged $108; median copayments were $30 (range, $0 to $4,792). Mean total monthly expenditures for imatinib nearly doubled between 2002 and 2011, from $2,798 to $4,892. Approximately 17% of patients with higher copayments and 10% with lower copayments discontinued TKIs during the first 180 days following initiation (adjusted risk ratio [aRR], 1.70; 95% CI, 1.30 to 2.22). Similarly, patients with higher copayments were 42% more likely to be nonadherent (aRR, 1.42; 95% CI, 1.19 to 1.69).
  
  
  CONCLUSIONS
  Patients with higher copayments are more likely to discontinue or be nonadherent to TKIs. Given the importance of these therapies for patients with CML, our data suggest a critical need to reduce patient costs for these therapies.
authors.affiliation: Stacie B. Dusetzina, School of Medicine and Lineberger Comprehensive Cancer Center and Cecil G. Sheps Center for Health Services Research; Stacie B. Dusetzina and Aaron N. Winn, Gillings School of Global Public Health; University of North Carolina at Chapel Hill, Chapel Hill, NC; Gregory A. Abel, Dana-Farber Cancer Institute; Haiden A. Huskamp and Nancy L. Keating, Harvard Medical School; and Nancy L. Keating, Brigham and Women's Hospital, Boston, MA.
authors.forename: Stacie B
authors.initials: SB
authors.lastname: Dusetzina
authors.forename: Aaron N
authors.initials: AN
authors.lastname: Winn
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Abel
authors.forename: Haiden A
authors.initials: HA
authors.lastname: Huskamp
authors.forename: Nancy L
authors.initials: NL
authors.lastname: Keating
mesh_terms: D000328:Adult; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000191:economics*; D001549:Benzamides / Q000008:administration & dosage / Q000191:economics*; D017047:Cost Sharing; D016527:Drug Costs; D005260:Female; D005102:Health Expenditures; D006801:Humans; D000068877:Imatinib Mesylate; D019458:Insurance Coverage; D007348:Insurance, Health; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000188:drug therapy* / Q000191:economics* / Q000201:enzymology; D008297:Male; D008875:Middle Aged; D010879:Piperazines / Q000008:administration & dosage / Q000191:economics*; D047428:Protein Kinase Inhibitors / Q000008:administration & dosage / Q000191:economics*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors*; D011743:Pyrimidines / Q000008:administration & dosage / Q000191:economics*; D014481:United States; D016903:Drug Monitoring
chemical_list: D000970:Antineoplastic Agents; D001549:Benzamides; D010879:Piperazines; D047428:Protein Kinase Inhibitors; D011743:Pyrimidines; D000068877:Imatinib Mesylate; D011505:Protein-Tyrosine Kinases