Conflict of interest
Naoyuki Hasegawa, Yoshimi Ito, Masamichi Yamaura, Masato Endo, Kazunori Ishige, Kuniaki Fukuda, Ichinosuke Hyodo, Yuji Mizokami declare that they have no conflict of interest.
Human and animal 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 was obtained from all patients for being included in the study.