CYP2C19 and transient ischemic attack: To address the latter limitation, a meta-analysis of individual participant data should be performed to obtain adjusted RRs and to assess the impact of factors, such as PPIs or antidepressants coadministration as well as cigarette smoking, on the association of CYP2C19 genotype with efficacy and safety of clopidogrel therapy in stroke/TIA patients.