Funding for this research was provided by:
Mashhad University of Medical Sciences (1)
Received: 10 December 2018
Accepted: 24 July 2019
First Online: 30 July 2019
Ethics approval and consent to participate
: The Ethics Committee of Mashhad University of Medical Sciences, Mashhad, Iran, approved the study (Ethic code: 931188). All participants and their parents completed informed written consent.
: Not applicable.
: The authors declare that they have no competing interests.