Received: 6 October 2018
Accepted: 16 May 2019
First Online: 24 May 2019
Ethics approval and consent to participate
: The study protocol was approved by the Bioethics Committee of the Medical University of Lodz (Document No. RNN / 360/14 / KB of 05.13.2014). Participating was voluntary and returning the questionnaire was taken as consent to participate in the study.
: Not applicable.
: The authors declare that they have no competing interests.
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