Text and Data Mining valid from 2019-01-29
Received: 15 October 2018
Accepted: 16 January 2019
First Online: 29 January 2019
Compliance with ethical standards
: The authors declare no funding source or conflicts of interest to declare.
: This retrospective study had been approved by the Institutional Review Board at National Health Insurance Service Ilsan Hospital (no. 2017-08-007-001).
: For this kind of study formal consent is note required.