title: Comparative effectiveness of generic versus brand-name antiepileptic medications.
abstract: OBJECTIVE
  The objective of this study was to compare treatment persistence and rates of seizure-related events in patients who initiate antiepileptic drug (AED) therapy with a generic versus a brand-name product.
  
  
  METHODS
  We used linked electronic medical and pharmacy claims data to identify Medicare beneficiaries who initiated one of five AEDs (clonazepam, gabapentin, oxcarbazepine, phenytoin, zonisamide). We matched initiators of generic versus brand-name versions of these drugs using a propensity score that accounted for demographic, clinical, and health service utilization variables. We used a Cox proportional hazards model to compare rates of seizure-related emergency room (ER) visit or hospitalization (primary outcome) and ER visit for bone fracture or head injury (secondary outcome) between the matched generic and brand-name initiators. We also compared treatment persistence, measured as time to first 14-day treatment gap, between generic and brand-name initiators.
  
  
  RESULTS
  We identified 19,760 AED initiators who met study eligibility criteria; 18,306 (93%) initiated a generic AED. In the matched cohort, we observed 47 seizure-related hospitalizations and ER visits among brand-name initiators and 31 events among generic initiators, corresponding to a hazard ratio of 0.53 (95% confidence interval, 0.30 to 0.96). Similar results were observed for the secondary clinical endpoint and across sensitivity analyses. Mean time to first treatment gap was 124.2 days (standard deviation [sd], 125.8) for brand-name initiators and 137.9 (sd, 148.6) for generic initiators.
  
  
  CONCLUSIONS
  Patients who initiated generic AEDs had fewer adverse seizure-related clinical outcomes and longer continuous treatment periods before experiencing a gap than those who initiated brand-name versions.
authors.affiliation: Division of Pharmacoepidemiology and Pharmacoeconomics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA. Electronic address: jgagne1@partners.org.
authors.forename: Joshua J
authors.initials: JJ
authors.lastname: Gagne
authors.affiliation: Division of Pharmacoepidemiology and Pharmacoeconomics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
authors.forename: Aaron S
authors.initials: AS
authors.lastname: Kesselheim
authors.affiliation: Division of Pharmacoepidemiology and Pharmacoeconomics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
authors.forename: Niteesh K
authors.initials: NK
authors.lastname: Choudhry
authors.affiliation: CVS Health, Woonsocket, RI, USA.
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Polinski
authors.affiliation: CVS Health, Woonsocket, RI, USA.
authors.forename: David
authors.initials: D
authors.lastname: Hutchins
authors.affiliation: CVS Health, Woonsocket, RI, USA.
authors.forename: Olga S
authors.initials: OS
authors.lastname: Matlin
authors.affiliation: CVS Health, Woonsocket, RI, USA.
authors.forename: Troyen A
authors.initials: TA
authors.lastname: Brennan
authors.affiliation: Division of Pharmacoepidemiology and Pharmacoeconomics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
authors.forename: Jerry
authors.initials: J
authors.lastname: Avorn
authors.affiliation: CVS Health, Woonsocket, RI, USA.
authors.forename: William H
authors.initials: WH
authors.lastname: Shrank
mesh_terms: D000368:Aged; D000927:Anticonvulsants / Q000009:adverse effects / Q000627:therapeutic use*; D015331:Cohort Studies; D016568:Drugs, Generic / Q000009:adverse effects / Q000627:therapeutic use*; D057286:Electronic Health Records; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data; D023381:Endpoint Determination; D004827:Epilepsy / Q000188:drug therapy*; D005260:Female; D006801:Humans; D008297:Male; D008498:Medical Record Linkage; D006278:Medicare; D010594:Pharmacies; D057216:Propensity Score; D012959:Socioeconomic Factors; D014481:United States
chemical_list: D000927:Anticonvulsants; D016568:Drugs, Generic
keywords: Antiepileptic drugs; Comparative effectiveness; Generics