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Article History

Received: 6 November 2017

Revised: 30 January 2018

Accepted: 15 February 2018

First Online: 1 March 2018

Compliance with ethical standards

:

: All authors certify that they have no affiliations with or involvement in any organisation or entity with any financial interest (such as honoraria; educational grants; participation in speakers’ bureaus; membership, employment, consultancies, stock ownership or other equity interest; and expert testimony or patent-licencing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge or beliefs) in the subject matter or materials discussed in this manuscript.

: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional research committee (ethics committee of the University Hospital Tübingen) and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

: Informed consent was obtained from all individual participants included in the study.