We thank Drs Dai, Jiang, and Sun for their comments. We agree that assessing the risk of ischemic stroke among users of proton pump inhibitors (PPIs) with and without coadministration of clopidogrel would be worthwhile, particularly given the concern that both drugs may be metabolized by CYP2C19.1 However, our ability to test this association within our prospective study was limited by the relatively short follow-up period after the use of clopidogrel became routine.