Funding for this research was provided by:
National Research Council Sri Lanka (NRC 12-140)
Received: 12 November 2018
Accepted: 4 July 2019
First Online: 12 July 2019
Ethics approval and consent to participate
: The study was approved by the Ethics Review Committee of the Faculty of Medicine, University of Colombo, Sri Lanka (EC/06/062).
: Not applicable.
: The authors declare that they have no competing interests.