Text and Data Mining valid from 2019-01-14
Received: 31 May 2018
Accepted: 2 January 2019
First Online: 14 January 2019
Ethics approval and consent to participate
: All participants provided written informed consent and the study was approved by the Regional Ethical Review Board in Umeå, Sweden (dnr 2011–199-31 M).
: Not applicable.
: The authors declare that they have no competing interests.
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