Text and Data Mining valid from 2019-04-10
Received: 9 May 2018
Accepted: 6 March 2019
First Online: 10 April 2019
Compliance with ethical guidelines
: C. Kirschneck, C. Rohn, P. Proff and C. Reicheneder declare that they have no competing interests.
: All procedures performed were in accordance with the ethical standards of the institutional ethics committee and the 1964 Helsinki declaration and its later amendments. Informed consent was obtained from all individual participants included in the study and in addition, if underage, from their legal guardians.