Funding for this research was provided by:
Text and Data Mining valid from 2018-07-25
Received: 21 February 2018
Accepted: 28 June 2018
First Online: 25 July 2018
Ethics approval and consent to participate
: The study was approved by the regional ethics board in Linköping, and has been performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments.
: All participants gave informed consent for participation in the study, including the publishing of results.
: The authors declare that they have no competing interests.
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