Text and Data Mining valid from 2019-03-02
Received: 29 November 2018
Revised: 20 February 2019
Accepted: 20 February 2019
First Online: 2 March 2019
Compliance with ethical standards
: The study was approved by the institutional review board of Faculty of Medicine, Khon Kaen University, Thailand (IRB no. #HE591399), before enrolling any participants.
: The authors declare that they have no conflict of interest.