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April 16, 2003

Clopidogrel and Percutaneous Coronary Interventions

Author Affiliations

Letters Section Editor: Stephen J. Lurie, MD, PhD, Senior Editor.

JAMA. 2003;289(15):1925-1927. doi:10.1001/jama.289.15.1925-a

In Reply: Dr Choudhury suggests that selection bias may have contributed to the difference in outcomes with clopidogrel pretreatment of less vs greater than 6 hours. As we noted in our article, there was no difference in patient baseline characteristics based on time of pretreatment, and all subgroups of patients derived similar benefit, or lack of it, based on the timing of pretreatment. Nonetheless, it is possible that unmeasured variables differed between the 2 groups. Choudhury, as well as Dr Bridges and Dr Borja and colleagues highlight the methodological issues with evaluating multiple interventions in clinical trials and the lack of a factorial design in our study. We agree that rerandomization would have been ideal. However, a lack of any plausible mechanism for a single loading dose of clopidogrel being able to prevent stokes, spontaneous myocardial infarctions, and death 1 to 12 months following its administration helped us decide to choose the design we did rather than the admittedly preferred factorial design suggested by Bridges and Borja and colleagues. Such a design would not only have been far more costly, but would have also required a much larger sample size.