Received: 12 December 2017
Accepted: 2 May 2018
First Online: 9 May 2018
Ethics approval and consent to participate
: The study was approved by the local ethics committee, Kantonale Ethikkommission Zürich, Stampfenbachstrasse 121, 8090 Zürich, Tel + 41 (0)43259 79 70 and registered under registration number PB 2016–00769. The need for written informed consent form from each patient has been waived by ethics committee due to retrospective manner of the study.
: The authors declare that they have no competing interests.
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