Editor—I am delighted to find that Van Overmeire et al 1 have acquired evidence to support the view that ibuprofen may be a useful treatment for patent ductus arteriosus (PDA). However, their paper may mislead. Their study suggests that there is no more than a 30% difference in the efficacy of indomethacin and ibuprofen for closing PDA. Unfortunately, a 30% difference is often seen as adequate to prove the superiority of one treatment over another, rather than to demonstrate …