Funding for this research was provided by:
Health Insurance System Research Office
Text and Data Mining valid from 2018-03-27
Received: 11 June 2017
Accepted: 14 March 2018
First Online: 27 March 2018
Ethics approval and consent to participate
: The study protocol was approved by the Institutional Review Board, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand on 4 April 2015 (Reference number 117/57). It is based on an existing secondary dataset so there is no need for a consent to participate. Individual identification number has been encrypted. The dataset was used with the permission of NHSO, and the data cannot be shared.
: Not applicable.
: The authors declare that they have no competing interests.
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