Article History
Received: 18 September 2018
Revised: 30 December 2018
Accepted: 21 January 2019
First Online: 31 January 2019
Compliance with ethical standards
:
: The authors declare that they have no conflicts of interest.
: Approval for the retrospective study was obtained from the research ethics committee of Chaoyang Hospital affiliated with the Capital Medical University.
: All individual participants included in the study provided informed consent.