Funding for this research was provided by:
Foundation award from the Canadian Institutes of Health Research (FDN 159902)
Text and Data Mining valid from 2019-01-25
Received: 27 November 2018
Accepted: 2 January 2019
First Online: 25 January 2019
Compliance with ethical standards
: The authors declare that they have no conflict of interest.
: The study was approved by the Nagasaki University School of Medicine Research Ethics Committee (Approval no. 16082210).
: As this study was a retrospective cohort study, written informed consent was not obtained. However, after approval from the ethics committee of our institute, we have shown the document of “Disclosure of information on clinical research” in our homepage to give the subjects opportunity to declare their will not to participate in this study.