Received: 2 May 2018
Accepted: 6 March 2019
First Online: 13 March 2019
: The authors declare that they have no competing interests.
: The study was approved by the regional Ethical Review Board, Linköping, Sweden, no. 2014/111–31. Date: 26-03-2016. Informed consent is not applicable.Informed consent was not required, according to national guidelines, since this is a register study with an ethical approval from the ethical review board and permission to use data was obtained from the register holders.
: Not applicable.
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