Funding for this research was provided by:
Pfizer Health Research Foundation in Japan (International research grant)
Received: 21 May 2019
Accepted: 24 October 2019
First Online: 8 November 2019
Ethics approval and consent to participate
: This study was approved by the Institutional Review Board of Bach Mai Hospital. Written informed consent was obtained from all participants.
: Not applicable.
: The authors declare that they have no competing interests.