Received: 11 March 2018
Accepted: 30 December 2018
First Online: 25 January 2019
Ethics approval and consent to participate
: The study protocol has been approved by The Ethics Committee of Nicolaus Copernicus University in Toruń, Ludwik Rydygier Collegium Medicum in Bydgoszcz (approval number KB 597/2016). All study-related procedures can be performed only after obtaining written informed consent from the participants.
: Consent for publication is not applicable.
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.