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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
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.

Drug Resistance

Study Type: Observational
Study Design: Observational Model: Cohort
Time Perspective: Cross-Sectional
Official Title: Aspirin- and Clopidogrel-Resistance: Non-compliance and Other Contributing Factors

Resource links provided by NLM:

Further study details as provided by University Hospital, Basel, Switzerland:

Primary Outcome Measures:
  • Platelet aggregation, initial and after one week under compliance monitoring. [ Time Frame: 1 week ]

Secondary Outcome Measures:
  • 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 ]

Biospecimen Retention:   Samples With DNA
blood samples for routine laboratory testing and platelet aggregometry blood samples for pharmacogenetic analysis

Enrollment: 82
Study Start Date: May 2010
Study Completion Date: October 2011
Primary Completion Date: June 2011 (Final data collection date for primary outcome measure)
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


Ages Eligible for Study:   45 Years and older   (Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No
Sampling Method:   Probability Sample
Study Population
Patients with a prescription for aspirin and/or clopidogrel seeing their general practitioner (GP) for any purpose

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
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT01039480

Study Centre at Aarelab AG, Olten
Olten, Solothurn, Switzerland, 4600
Sponsors and Collaborators
University Hospital, Basel, Switzerland
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
  More Information

Additional Information:
Publications automatically indexed to this study by Identifier (NCT Number):
Responsible Party: Philipp N. Walter, Investigator, Pharmaceutical Care Research Group Identifier: NCT01039480     History of Changes
Other Study ID Numbers: PCRG_003_PW
Study First Received: December 23, 2009
Last Updated: February 8, 2012

Keywords provided by University Hospital, Basel, Switzerland:
pharmacological biomarker
compliance monitoring
platelet aggregometry
Platelet Aggregation Inhibitors
Medication Non-Compliance

Additional relevant MeSH terms:
Platelet Aggregation Inhibitors
Anti-Inflammatory Agents, Non-Steroidal
Analgesics, Non-Narcotic
Sensory System Agents
Peripheral Nervous System Agents
Physiological Effects of Drugs
Anti-Inflammatory Agents
Antirheumatic Agents
Fibrinolytic Agents
Fibrin Modulating Agents
Molecular Mechanisms of Pharmacological Action
Cyclooxygenase Inhibitors
Enzyme Inhibitors
Purinergic P2Y Receptor Antagonists
Purinergic P2 Receptor Antagonists
Purinergic Antagonists
Purinergic Agents
Neurotransmitter Agents
Cytochrome P-450 CYP2C19 Inhibitors
Cytochrome P-450 Enzyme Inhibitors processed this record on August 18, 2017