title: Methodological issues of retrospective studies assessing health outcomes of potential clopidogrel-statin interaction.
abstract: OBJECTIVE
  Clopidogrel and statins have been commonly coprescribed to patients with atherosclerotic diseases. Clopidogrel-statin interaction was initially described by ex vivo studies, but was not well supported by studies examining health outcomes. This personal view article aims to discuss methodological issues of these studies, especially the retrospective studies assessing health outcomes.
  
  
  METHODS
  A comprehensive literature search was conducted to identify journal articles of clopidogrel-statin interaction that were published in English since January 2003.
  
  
  RESULTS
  The limitations of retrospective studies include lack of central blinded adjudication of clinical events, incomplete assessment of confounders, inadequate comparison groups and inconsistent use of medication dosage.
  
  
  CONCLUSIONS
  A well-designed retrospective study may better understand potential clopidogrel-statin interaction and its clinical impacts.
authors.affiliation: Division of Pharmacy Practice and Administration, The University of Missouri, Kansas City, MO, USA.
authors.forename: Yifei
authors.initials: Y
authors.lastname: Liu
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Unni
mesh_terms: D000077144:Clopidogrel; D004347:Drug Interactions; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000008:administration & dosage / Q000009:adverse effects*; D017063:Outcome Assessment, Health Care / Q000379:methods; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage / Q000009:adverse effects; D012107:Research Design; D012189:Retrospective Studies; D013988:Ticlopidine / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives*
chemical_list: D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D010975:Platelet Aggregation Inhibitors; D000077144:Clopidogrel; D013988:Ticlopidine
keywords: clopidogrel; clopidogrel-statin interaction; research method; statin