title: Effect of cost sharing on adherence to evidence-based medications in patients with acute coronary syndrome.
abstract: Cost-sharing scheme for pharmaceuticals in Spain changed in July 2012. Our aim was to assess the impact of this change on adherence to essential medication in patients with acute coronary syndrome (ACS) in the region of Valencia.
  
  
  
  Population-based retrospective cohort of 10 563 patients discharged alive after an ACS in 2009-2011. We examined a control group (low-income working population) that did not change their coinsurance status, and two intervention groups: pensioners who moved from full coverage to 10% coinsurance and middle-income to high-income working population, for whom coinsurance rose from 40% to 50% or 60%. Weekly adherence rates measured from the date of the first prescription. Days with available medication were estimated by linking prescribed and filled medications during the follow-up period.
  
  
  
  Cost-sharing change made no significant differences in adherence between intervention and control groups for essential medications with low price and low patient maximum coinsurance, such as antiplatelet and beta-blockers. For costlier ACE inhibitor or an angiotensin II receptor blocker (ACEI/ARB) and statins, it had an immediate effect in the proportion of adherence in the pensioner group as compared with the control group (6.8% and 8.3% decrease of adherence, respectively, p<0.01 for both). Adherence to statins decreased for the middle-income to high-income group as compared with the control group (7.8% increase of non-adherence, p<0.01). These effects seemed temporary.
  
  
  
  Coinsurance changes may lead to decreased adherence to proven, effective therapies, especially for higher priced agents with higher patient cost share. Consideration should be given to fully exempt high-risk patients from drug cost sharing.
authors.affiliation: Department of Quantitative Methods in Economics and Management, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.
authors.forename: Beatriz
authors.initials: B
authors.lastname: González López-Valcárcel
authors.affiliation: Health Services Research Unit, Center for Public Health Research (CSISP-FISABIO), Valencia, Spain.|Red de Investigación en Servicios de Salud en Enfermedades Crónicas (REDISSEC), Valencia, Spain.|Navarrabiomed Biomedical Research Centre, Pamplona, Spain.
authors.forename: Julián
authors.initials: J
authors.lastname: Librero
authors.affiliation: Health Services Research Unit, Center for Public Health Research (CSISP-FISABIO), Valencia, Spain.|Red de Investigación en Servicios de Salud en Enfermedades Crónicas (REDISSEC), Valencia, Spain.
authors.forename: Aníbal
authors.initials: A
authors.lastname: García-Sempere
authors.affiliation: Centre for Research in Health and Economics (CRES), Pompeu Fabra University, Barcelona, Spain.
authors.forename: Luz María
authors.initials: LM
authors.lastname: Peña
authors.affiliation: Health Services Research Unit, Center for Public Health Research (CSISP-FISABIO), Valencia, Spain.
authors.forename: Sofía
authors.initials: S
authors.lastname: Bauer
authors.affiliation: Centre for Research in Health and Economics (CRES), Pompeu Fabra University, Barcelona, Spain.
authors.forename: Jaume
authors.initials: J
authors.lastname: Puig-Junoy
authors.affiliation: Department of Economic Analysis, University of Castilla-La Mancha, Toledo, Spain.
authors.forename: Juan
authors.initials: J
authors.lastname: Oliva
authors.affiliation: Health Services Research Unit, Center for Public Health Research (CSISP-FISABIO), Valencia, Spain.
authors.forename: Salvador
authors.initials: S
authors.lastname: Peiró
authors.affiliation: Health Services Research Unit, Center for Public Health Research (CSISP-FISABIO), Valencia, Spain.|Red de Investigación en Servicios de Salud en Enfermedades Crónicas (REDISSEC), Valencia, Spain.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Sanfélix-Gimeno
mesh_terms: D054058:Acute Coronary Syndrome / Q000188:drug therapy* / Q000191:economics; D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use*; D000328:Adult; D000368:Aged; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000627:therapeutic use*; D017047:Cost Sharing; D016527:Drug Costs; D005260:Female; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000627:therapeutic use*; D008297:Male; D055118:Medication Adherence; D008875:Middle Aged; D010349:Patient Compliance; D012189:Retrospective Studies
chemical_list: D000319:Adrenergic beta-Antagonists; D000806:Angiotensin-Converting Enzyme Inhibitors; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors
keywords: Difference-indifferences; acute coronary syndrome; cost-sharing; medication adherence