Funding for this research was provided by:
Karolinska Institutet (Björnsson-Karlssons fond)
Received: 19 April 2017
Accepted: 14 December 2017
First Online: 15 January 2018
Ethics approval and consent to participate
: Ethical approval for the study was obtained from the Regional Ethical Review Board in Stockholm. Because of the retrospective nature of the study, informed consent was waived.
: Not applicable
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.