Received: 18 August 2019
Accepted: 6 February 2020
First Online: 21 February 2020
Ethics approval and consent to participate
: The ethical approval was obtained from The Ethics Review Sub-Committee, Thammasat University (049/2559) Written consent has been taken from the participants. We maintained the confidentiality by replacing personal identifiers by a respondent codes; and using password protected electronic database.
: Not applicable
: The authors declare that they have no competing interests.