Text and Data Mining valid from 2019-11-15
Received: 17 September 2019
Accepted: 28 October 2019
First Online: 15 November 2019
Ethics approval and consent to participate
: The study was approved by the ethics committee of the Clinical Research Promotion Network Japan. Informed consent was waived because of its nature of retrospective analysis of existing data.
: Not applicable.
: The authors declare that they have no competing interests.