Table 1.

Data sources for thienopyridine-associated TTP

Data source	Ticlopidine-associated TTP cases	Clopidogrel-associated TTP cases	Prasugrel-associated TTP cases
Literature review (1991–2011)	21 publications	8 publications	0 publications
FDA Adverse Event Reporting System (1998–2011)	97 cases, 10 reported since 2002	197 cases, 140 reported since 2002	14 cases
Phase III clinical trials (1989–2010)	One TTP case reported among 2,932 ticlopidine-treated patients	No TTP cases reported among 27,961 clopidogrel-treated patients	No TTP cases reported among 1,769 prasugrel-treated patients
FDA-approved package inserts (1989–2011)	1996: warning added; 1998-“boxed” warning added	2000: warning added	2010: warning added
Surveys of therapeutic plasma exchange center and interventional cardiology laboratories (1998–1999)	Five TTP cases among 8,000 ticlopidine treated patients and nine TTP cases among 45,000 ticlopidine-treated patients	Nine clopidogrel-associated TTP cases identified	Not done
Administrative databases (1998–2001)	Two cases of ticlopidine-associated TTP identified among 15 million person-years of observation	One case of clopidogrel-associated TTP identified among 15 million person-years of observation	Not done
Laboratory-based study (2006–2008)	100% of 30 ticlopidine-associated TTP cases had neutralizing antibodies to ADAMTS-13 and < 10% ADAMTS-13 activity	0% of eight clopidogrel-associated TTP cases had neutralizing antibodies to ADAMTS-13 or < 10% ADAMTS-13 activity	Not done
Queries of medical personnel employed by thienopyridine manufacturers	No cases reported (1998)	One case was reported by an employee of the manufacturer of clopidogrel and one case was reported by an employee of the manufacturer of ticlopidine (1999)	To be determined (2011)

Abbreviations: ADAMTS-13, a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13; FDA, U.S. Food and Drug Administration; TTP, thrombotic thrombocytopenic purpura.