Funding for this research was provided by:
Forskningsrådet om Hälsa, Arbetsliv och Välfärd (FAS dnr 2009-0292)
Centrum fÖr Klinisk Forskning Dalarna (CKFUU-414041)
Received: 28 August 2018
Accepted: 10 June 2019
First Online: 20 June 2019
Ethics approval and consent to participate
: Informed consent was obtained through a letter sent home to the participants, stressing that participation in the study was voluntary. The consent procedure followed that of ‘opt out’, implying that no active consent was asked for. This procedure was in accordance with ethical standards at this time, and the study was approved by The Regional Ethical Review Board at the Medical Faculty, Umeå University (reference number 03–073).
: Not applicable.
: The authors declare that they have no competing interests.