title: The introduction of generic aromatase inhibitors and treatment adherence among Medicare D enrollees.
abstract: BACKGROUND
  Aromatase inhibitors (AIs) substantially reduce breast cancer mortality in clinical trials, but high rates of nonadherence to these long-term oral therapies have reduced their impact outside of trials. We examined the association of generic AI availability with AI adherence among a large national breast cancer cohort.
  
  
  METHODS
  Using a quasi-experimental prepost design, we examined the effect of generic AI introductions (7/2010 and 4/2011) on adherence among a national cohort of women with incident breast cancer in 2006 and 2007 who were enrolled in the Medicare D pharmaceutical coverage program. Medicare D claims were used to calculate AI adherence, defined as a medication possession ratio of 80% or more of eligible days, over 36 months. Multivariable logistic regression models estimated with generalized estimating equations were applied to longitudinal adherence data to control for possible confounders, including receipt of a Medicare D low-income subsidy, and to account for repeated measures. All statistical tests were two-sided.
  
  
  RESULTS
  Sixteen thousand four hundred sixty-two Medicare D enrollees were eligible. Adherence declined throughout the study. However, among women without a subsidy, the median quarterly out-of-pocket cost of anastrozole fell from $183 in the fourth quarter of 2009 to $15 in 2011, and declines in adherence were attenuated with generic AI introductions. Regression-adjusted adherence probabilities were estimated to be 5.4% higher after generic anastrozole was introduced in 2010 and 11% higher after generic letrozole/exemestane was introduced in 2011. Subsidy recipients had higher adherence rates throughout the study.
  
  
  CONCLUSIONS
  The introduction of generic medications attenuated the decline in adherence to AIs over three years of treatment among breast cancer survivors not receiving low-income subsidies for Medicare D coverage.
authors.affiliation: Center for Patient Care and Outcomes Research (JMN, SK, JC, EMW, ECS, AJS, PWL, LEP), Division of Hematology and Oncology, Department of Medicine (SK, JC), Division of Biostatistics, Department of the Institute for Health and Society (PWL), Division of General Internal Medicine, Department of Medicine (JMN, AB, LEP), Medical College of Wisconsin, Milwaukee, WI. jneuner@mcw.edu.
authors.forename: Joan M
authors.initials: JM
authors.lastname: Neuner
authors.affiliation: Center for Patient Care and Outcomes Research (JMN, SK, JC, EMW, ECS, AJS, PWL, LEP), Division of Hematology and Oncology, Department of Medicine (SK, JC), Division of Biostatistics, Department of the Institute for Health and Society (PWL), Division of General Internal Medicine, Department of Medicine (JMN, AB, LEP), Medical College of Wisconsin, Milwaukee, WI.
authors.forename: Sailaja
authors.initials: S
authors.lastname: Kamaraju
authors.affiliation: Center for Patient Care and Outcomes Research (JMN, SK, JC, EMW, ECS, AJS, PWL, LEP), Division of Hematology and Oncology, Department of Medicine (SK, JC), Division of Biostatistics, Department of the Institute for Health and Society (PWL), Division of General Internal Medicine, Department of Medicine (JMN, AB, LEP), Medical College of Wisconsin, Milwaukee, WI.
authors.forename: John A
authors.initials: JA
authors.lastname: Charlson
authors.affiliation: Center for Patient Care and Outcomes Research (JMN, SK, JC, EMW, ECS, AJS, PWL, LEP), Division of Hematology and Oncology, Department of Medicine (SK, JC), Division of Biostatistics, Department of the Institute for Health and Society (PWL), Division of General Internal Medicine, Department of Medicine (JMN, AB, LEP), Medical College of Wisconsin, Milwaukee, WI.
authors.forename: Erica M
authors.initials: EM
authors.lastname: Wozniak
authors.affiliation: Center for Patient Care and Outcomes Research (JMN, SK, JC, EMW, ECS, AJS, PWL, LEP), Division of Hematology and Oncology, Department of Medicine (SK, JC), Division of Biostatistics, Department of the Institute for Health and Society (PWL), Division of General Internal Medicine, Department of Medicine (JMN, AB, LEP), Medical College of Wisconsin, Milwaukee, WI.
authors.forename: Elizabeth C
authors.initials: EC
authors.lastname: Smith
authors.affiliation: Center for Patient Care and Outcomes Research (JMN, SK, JC, EMW, ECS, AJS, PWL, LEP), Division of Hematology and Oncology, Department of Medicine (SK, JC), Division of Biostatistics, Department of the Institute for Health and Society (PWL), Division of General Internal Medicine, Department of Medicine (JMN, AB, LEP), Medical College of Wisconsin, Milwaukee, WI.
authors.forename: Alana
authors.initials: A
authors.lastname: Biggers
authors.affiliation: Center for Patient Care and Outcomes Research (JMN, SK, JC, EMW, ECS, AJS, PWL, LEP), Division of Hematology and Oncology, Department of Medicine (SK, JC), Division of Biostatistics, Department of the Institute for Health and Society (PWL), Division of General Internal Medicine, Department of Medicine (JMN, AB, LEP), Medical College of Wisconsin, Milwaukee, WI.
authors.forename: Alicia J
authors.initials: AJ
authors.lastname: Smallwood
authors.affiliation: Center for Patient Care and Outcomes Research (JMN, SK, JC, EMW, ECS, AJS, PWL, LEP), Division of Hematology and Oncology, Department of Medicine (SK, JC), Division of Biostatistics, Department of the Institute for Health and Society (PWL), Division of General Internal Medicine, Department of Medicine (JMN, AB, LEP), Medical College of Wisconsin, Milwaukee, WI.
authors.forename: Purushottam W
authors.initials: PW
authors.lastname: Laud
authors.affiliation: Center for Patient Care and Outcomes Research (JMN, SK, JC, EMW, ECS, AJS, PWL, LEP), Division of Hematology and Oncology, Department of Medicine (SK, JC), Division of Biostatistics, Department of the Institute for Health and Society (PWL), Division of General Internal Medicine, Department of Medicine (JMN, AB, LEP), Medical College of Wisconsin, Milwaukee, WI.
authors.forename: Liliana E
authors.initials: LE
authors.lastname: Pezzin
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000077384:Anastrozole; D000730:Androstadienes / Q000008:administration & dosage / Q000191:economics; D000970:Antineoplastic Agents / Q000008:administration & dosage* / Q000191:economics; D047072:Aromatase Inhibitors / Q000008:administration & dosage* / Q000191:economics; D001943:Breast Neoplasms / Q000188:drug therapy*; D015331:Cohort Studies; D016527:Drug Costs; D016568:Drugs, Generic; D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D000077289:Letrozole; D006278:Medicare; D009570:Nitriles / Q000008:administration & dosage / Q000191:economics; D065228:Non-Randomized Controlled Trials as Topic; D011203:Poverty; D014230:Triazoles / Q000008:administration & dosage / Q000191:economics; D014481:United States; D016903:Drug Monitoring
chemical_list: D000730:Androstadienes; D000970:Antineoplastic Agents; D047072:Aromatase Inhibitors; D016568:Drugs, Generic; D009570:Nitriles; D014230:Triazoles; D000077384:Anastrozole; D000077289:Letrozole; C056516:exemestane