Text and Data Mining valid from 2019-11-21
Received: 16 September 2019
Accepted: 2 November 2019
First Online: 21 November 2019
Ethics approval and consent to participate
: This study was approved by the ethical review board of Kochi Medical School and conducted in accordance with the ethical standards of the Declaration of Helsinki.
: Not applicable.
: The authors declare that they have no competing interests.