Response to "Comment on 'Clopidogrel can be an effective complementary prophylactic for drug-refractory migraine with patent foramen ovale'".

Dear Editor, We thank Haghdoost and Sacco for their interest and comment1 on our article.2 Our study is a single-center non-randomized open-label trial and each patient was enrolled with a rigorous diagnosis by the neurologist. We ensure that each patient was well represented. The sample size is very small for setting a placebo group, so our study is a self-controlled experiment. However, a meta-analysis3 to quantify the placebo effect of migraine preventive treatment reported that, in the 22 studies they included, they did not find that the percentage of responders with the placebo effect was higher than 35% and the frequency of …