Clopidogrel-Associated TTP An Update of Pharmacovigilance Efforts Conducted by Independent Researchers, Pharmaceutical Suppliers, and the Food and Drug Administration

Anaadriana Zakarija, Nicholas Bandarenko, Dilip K. Pandey, Amy Auerbach, Dennis W. Raisch, Benjamin Kim, Hau C. Kwaan, June M. McKoy, Brian P. Schmitt, Charles J. Davidson, Paul R. Yarnold, Philip B. Gorelick, Charles L. Bennett*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

95 Scopus citations


Background and Purpose - Since the 1999 identification of clopidogrel-associated thrombotic thrombocytopenic purpura (TTP) through independent active surveillance, subsequent cases have been identified by pharmaceutical suppliers of clopidogrel and the Food and Drug Administration (FDA). For cases of clopidogrel-associated TTP reported between 1998 to 2002, we evaluated the quality and timeliness of data from 3 reporting systems-independent active surveillance (n=13), pharmaceutical suppliers (n=24), and the FDA (n=13)-and identified prognostic factors associated with mortality. Methods - This study assessed the completeness of information on TTP diagnosis, treatment response, and causality from the 3 reporting systems. In addition, predictors of mortality were identified through classification tree analysis. Results - Completeness, timeliness, and certainty of diagnosis were best for cases obtained by active surveillance, intermediate for cases reported to the pharmaceutical supplier, and poorest for cases reported directly to the FDA. Clopidogrel had been used for ≤2 weeks by 65%. The survival rate for patients with clopidogrel-associated TTP was 71.2%. Receipt of therapeutic plasma exchange within 3 days of onset of TTP increased the likelihood of survival (100% versus 27.3%, P<0.001). Conclusions - Compared with reports submitted by suppliers of the FDA, reports obtained through active surveillance provided timelier and more complete information. Clopidogrel-associated TTP often occurs within 2 weeks of drug initiation, occasionally relapses, and has a high mortality if not treated promptly.

Original languageEnglish (US)
Pages (from-to)533-537
Number of pages5
Issue number2
StatePublished - Feb 2004


  • Adverse drug reaction reporting systems
  • Antiplatelet agents
  • Purpura, thrombotic thrombocytopenic

ASJC Scopus subject areas

  • Clinical Neurology
  • Cardiology and Cardiovascular Medicine
  • Advanced and Specialized Nursing


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