Received: 14 September 2017
Accepted: 16 February 2018
First Online: 28 February 2018
Ethics approval and consent to participate
: The ethical issues of this study was reviewed and approved by the Ethical Committee of the Ministry of Health, KSA. Approval of Education Authority was obtained. A written informed consent was obtained from the parents/ guardians of participating children.
: Not applicable.
: The authors declare that they have no competing interests.
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