Received: 25 February 2019
Accepted: 29 March 2019
First Online: 4 April 2019
Ethics approval and consent to participate
: The study was approved by the Bioethical Commission of Pomeranian Medical University in Szczecin (study no. KB-0012/36/11 with addendum KB-0012/84/12, KB-0012/130/15 and KB-0012/162/12). Informed consent was obtained from all participants of the study.
: Not applicable.
: The authors declare that they have no competing interests.
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