Text and Data Mining valid from 2019-01-30
Received: 23 August 2018
Accepted: 16 January 2019
First Online: 30 January 2019
Compliance with Ethical Standards
: The authors declare that they have no conflicts of interest.
: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki declaration and its later amendments.
: Informed consent was waived by the Institutional Review Board for this retrospective cohort study.