Received: 1 April 2019
Accepted: 17 December 2019
First Online: 30 December 2019
Ethics approval and consent to participate
: The ethics committee of the Zanjan University of Medical Sciences approved the study, and all participants completed the informed written consent before the study start.
: Not applicable.
: The authors declare that they have no competing interests. Besides, Maryam Khazaee-Pool as a member of the editorial board (Associate Editor) of BMC Public Health journal declare that she has no competing interests.