Funding for this research was provided by:
National Research Council Sri Lanka (15-149)
University of Colombo Sri Lanka (AP/3/2/2017/SG/09)
Received: 13 June 2019
Accepted: 23 January 2020
First Online: 12 February 2020
Ethics approval and consent to participate
: This study was approved by the Ethics Review Committee (EC-14-044), Faculty of Medicine, University of Colombo, Sri Lanka. Written informed consent was obtained from all participants.
: Not applicable.
: The authors declare that they have no competing interests.