Funding for this research was provided by:
Pfizer (No Number)
Received: 15 May 2019
Accepted: 25 July 2019
First Online: 18 September 2019
Ethics approval and consent to participate
: All participants gave written informed consent to the study, which was approved by the ethics committee of the University Duisburg-Essen, Germany.
: Consent for publication was obtained from those patients whose individual data are presented.
: TH received travel grants and research funding for the project from Pfizer, and AT received travel grants from Pfizer.