Funding for this research was provided by:
Text and Data Mining valid from 2019-05-17
Received: 8 November 2018
Accepted: 15 April 2019
First Online: 17 May 2019
Ethics approval and consent to participate
: The present study was approved by the Norwegian Centre for Research Data. All participants gave written or oral informed consent to participate. Some of the participants were not able to read or write and gave verbal consent. The participants that could not give written consent were provided with detailed information about the project and of the data treatment approved by the Norwegian Centre for Research Data. The study was conducted according to the ethical guidelines in the World Medical Association Declaration of Helsinki.
: Not applicable.
: The authors declare that they have no competing interests.
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