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Article History

Received: 25 February 2020

Accepted: 8 June 2020

First Online: 22 June 2020

Ethics approval and consent to participate

: This study was approved by the research ethics committee of Capital Medical University and was performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments. As it was a retrospective study the requirement for informed consent was waived.

: N/A.

: All authors declare that they have no competing interests.