Received: 2 August 2017
Accepted: 15 January 2018
First Online: 25 January 2018
Ethics approval and consent to participate
: The ethical clearance was approved by the ethics review committee, Faculty of Medicine, University of Peradeniya, Sri Lanka. This is a retrospective study and the permission to review data was obtained from administrative and health authorities.
: Not applicable.
: The authors declare that they have no competing interests.
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