Text and Data Mining valid from 2018-03-16
Received: 30 January 2018
Accepted: 7 March 2018
First Online: 16 March 2018
Compliance with ethical standards
: The authors declare that they have no conflict of interest
: For this type of study, formal consent is not required.
: This article does not contain any studies with human participants or animals performed by any of the authors.
: This type of study is based on aggregated data of already published studies. Informed consent can not be obtained from patients.