Text and Data Mining valid from 2019-04-11
Received: 25 January 2019
Accepted: 2 April 2019
First Online: 11 April 2019
Compliance with ethical standards
: The authors declare that they have no conflict of interest.
: This study was approved by the Institutional Review Board. This study complied with the principles of the 1964 Helsinki Declaration and its later amendments.
: Informed consent was waived because no intervention was involved, and no identifying patient information was included.