Received: 11 December 2017
Accepted: 26 July 2018
First Online: 3 August 2018
Ethics approval and consent to participate
: The investigations were carried out in accordance with the Declaration of Helsinki as revised in 1996, including written informed consent of all participants and the KORA S4/F4/FF4 studies were approved by the Ethics Committee of the Bavarian Medical Association.
: Not applicable.
: The authors declare that they have no competing interests.
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