Text and Data Mining valid from 2019-02-13
Received: 28 July 2018
Accepted: 6 February 2019
First Online: 13 February 2019
Compliance with ethical standards
: We declare that there are no potential competing interests in this research.
: This study was conducted according to the Declaration of Helsinki and institutional review board approval was obtained at each center participating in this research. An institutional IRB was granted through a local ethics committee at each location.