title: Response to the letter by Drs Li, Yao, Chang.
authors.affiliation: Hôpitaux universitaires Paris Nord Val-de-Seine, 46, rue Henri-Huchard, 75877 Paris cedex 18, France; EA REMES, université Paris Diderot, Sorbonne Paris cité, 75010 Paris, France. Electronic address: phmassin@gmail.com.
authors.forename: P
authors.initials: P
authors.lastname: Massin