Text and Data Mining valid from 2019-02-14
Received: 1 October 2018
Accepted: 29 January 2019
First Online: 14 February 2019
Compliance with ethical standards
: The authors declare that they have no conflict of interest.
: This study was approved by the regional ethics committee at Karolinska Institutet (No. 2004/5:9–639/5). Due to the character of the database and the anonymization of all data, no written informed consent was needed.