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Article History

Received: 12 August 2018

Revised: 17 October 2018

Accepted: 22 November 2018

First Online: 10 January 2019

Compliance with ethical standards

:

: The scientific guarantor of this publication is Marc Zins.

: The authors of this manuscript declare no relationships with any companies, whose products or services may be related to the subject matter of the article.

: One of the authors has significant statistical expertise.

: Written informed consent was waived by the Institutional Review Board.

: Institutional Review Board approval was obtained.

: • retrospective• observational• performed at one institution