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Aspirin and Clopidogrel Resistance Study

This study has been completed.
Information provided by:
University Hospital, Basel, Switzerland Identifier:
First received: December 23, 2009
Last updated: February 8, 2012
Last verified: February 2012
December 23, 2009
February 8, 2012
May 2010
June 2011   (Final data collection date for primary outcome measure)
Platelet aggregation, initial and after one week under compliance monitoring. [ Time Frame: 1 week ]
Same as current
Complete list of historical versions of study NCT01039480 on Archive Site
  • Data on compliance (measured by electronic compliance monitoring, Morisky MMAS-8 and BMQ Score) [ Time Frame: 1 week ]
  • Frequency of contributing factors to non-response in responders compared to non-responders (pharmacogenetics, clinical factors and drug-drug interactions) [ Time Frame: 4 weeks ]
Same as current
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Aspirin and Clopidogrel Resistance Study
Aspirin- and Clopidogrel-Resistance: Non-compliance and Other Contributing Factors
Resistance to antiplatelet drugs (aspirin, clopidogrel) is a recognized phenomenon with a prevalence from 17% to 35%. Resistance as detected by in vitro tests such as Multiple Electrode Aggregometry (MEA) has been shown to predict clinical therapy failure. Resistance can be caused by clinical, cellular and pharmacogenetic factors. Non compliance is suspected to be an important contributing factor. In this study, compliance will be assured with an electronical compliance monitoring system. Factors to non response will be identified to find plausible explanations when in vitro platelet aggregation inhibition is insufficient despite assured compliance. This study will help to disclose the relationship between compliance, biomarker and clinical outcome as well as to quantify the impact of non compliance to the resistance phenomenon as measured by MEA.
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Observational Model: Cohort
Time Perspective: Cross-Sectional
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Retention:   Samples With DNA
blood samples for routine laboratory testing and platelet aggregometry blood samples for pharmacogenetic analysis
Probability Sample
Patients with a prescription for aspirin and/or clopidogrel seeing their general practitioner (GP) for any purpose
Drug Resistance
Not Provided
  • dual therapy (ASS/CLO)
    patients with a prescription for dual antiplatelet therapy with aspirin AND clopidogrel
  • clopidogrel users (CLO)
    patients with a prescription for clopidogrel
  • aspirin users (ASP)
    patients with a prescription for aspirin
Walter PN, Tsakiris DA, Romanens M, Arnet I, Hersberger KE. Antiplatelet resistance in outpatients with monitored adherence. Platelets. 2014;25(7):532-8. doi: 10.3109/09537104.2013.845743. Epub 2013 Oct 31.

*   Includes publications given by the data provider as well as publications identified by Identifier (NCT Number) in Medline.
October 2011
June 2011   (Final data collection date for primary outcome measure)

Inclusion Criteria:

  • Patients prescribed aspirin and/or clopidogrel for both including both cardiovascular and cerebrovascular indications seeing their general practitioner in or nearby Olten/SO for any medical purpose
  • Patients with oral and written German language ability

Exclusion Criteria:

  • Patients living in care homes
  • Patients not preparing their drugs on their own (e.g. outpatient medical assistance through "spitex").
  • Patients with acute cardiac symptoms
Sexes Eligible for Study: All
45 Years and older   (Adult, Senior)
Contact information is only displayed when the study is recruiting subjects
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Philipp N. Walter, Investigator, Pharmaceutical Care Research Group
University Hospital, Basel, Switzerland
Not Provided
Study Chair: Kurt E Hersberger, PhD Pharmaceutical Care Research Group, Departement of Pharmacy, University Basel
Principal Investigator: Michel Romanens, MD Kardiologische Praxis, Olten/SO
Study Director: Dimitrios Tsakiris, MD Hemostaseology Lab, University Hospital Basel
Principal Investigator: Philipp N Walter, MSc Pharmaceutical Care Research Group, Department of Pharmacy, University of Basel
University Hospital, Basel, Switzerland
February 2012

ICMJE     Data element required by the International Committee of Medical Journal Editors and the World Health Organization ICTRP