Funding for this research was provided by:
Bundesministerium für Gesundheit (IIA5-2513NIK006/321-4471-02/129)
Received: 2 March 2018
Accepted: 19 April 2018
First Online: 2 May 2018
Ethics approval and consent to participate
: Not applicable.
: The authors declare that they have no competing interests.
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