Funding for this research was provided by:
Linköpings Universitet (2016186-14)
Text and Data Mining valid from 2020-03-06
Received: 21 November 2019
Accepted: 14 February 2020
First Online: 6 March 2020
Ethics approval and consent to participate
: The study has been subject to ethical evaluation and was approved by the regional ethical review board in Linköping (Dnr 2016/347–31). Since we used administrative data informed consent was not regarded as necessary by the board.
: Not applicable.
: The authors declare that they have no competing interests.