Conflict of interest
Daizo Fukushima,Shigeki Imai, Noriyuki Nishino, Kohichi Hamada, Yasunori Horikawa, Yoshiki Shiwa, Shinya Nishida, Ryota Koyanagi, Hitoshi Wada, Hideo Sakuma declare that they have no conflict of interest.
Human rights
All procedures followed have been performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments.
Informed consent
Informed consent was obtained from all patients for being included in the study.