[Creative mathematics with clopidogrel; exaggeration of the preventive effect by manufacturer].
A number of Dutch medical journals recently carried an advertisement stating that clopidogrel treatment reduced the number of ischaemic complications with 26%, compared with aspirin treatment. This is a miscalculation: the actual reduction is 0.51% in absolute rates, and 8.7% in relative terms. The error by Sanofi-Synthelabo arose by comparison of the event rates for clopidogrel (5.32%) as well as for aspirin (5.83%) with that in an imaginary placebo group (7.77%), yielding a reduction of ischaemic complications of 2.45% and 1.94% respectively; erroneous comparison of these two numbers leads to a difference of 26%.
Algra
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A
Academisch Ziekenhuis, Julius Centrum voor Patiëntgebonden Onderzoek, Utrecht.
van Gijn
J
J
Kappelle
L J
LJ
Koudstaal
P J
PJ
Stam
J
J
Vermeulen
M
M
D000329:Advertising; D000077144:Clopidogrel; D003627:Data Interpretation, Statistical; D004345:Drug Industry / Q000379:methods*; D006801:Humans; D009203:Myocardial Infarction / Q000517:prevention & control; D009426:Netherlands; D010975:Platelet Aggregation Inhibitors / Q000627:therapeutic use*; D016032:Randomized Controlled Trials as Topic / Q000706:statistics & numerical data; D020521:Stroke / Q000517:prevention & control; D013988:Ticlopidine / Q000031:analogs & derivatives* / Q000627:therapeutic use
D010975:Platelet Aggregation Inhibitors; D000077144:Clopidogrel; D013988:Ticlopidine