Text and Data Mining valid from 2020-01-09
Received: 21 September 2019
Accepted: 27 December 2019
First Online: 9 January 2020
Compliance with ethical standards
: The authors declare that they have no conflict of interest.
: The institutional review board of our hospital approved this retrospective study.For this type of study, formal consent was not required.
: Informed consent was obtained from all individual participants included in the study.