Received: 1 June 2021
Accepted: 19 November 2021
First Online: 5 December 2021
: Ethical approval for this study was obtained from the Ethical commission at Medical University “Prof. Dr. Paraskev Stoyanov” Varna (<b>Approval № 83/ 16.05.2019</b>). All participants signed an informed consent prior their participation in the present study.
: The authors give their consent for the publication in the Journal.
: The authors declare that there is no conflict of interest.