Funding for this research was provided by:
Uppsala County Association Against Heart and Lung Diseases
Received: 26 April 2018
Accepted: 5 November 2018
First Online: 26 November 2018
Ethics approval and consent to participate
: The study was approved by the regional Human Research Ethics Committee, Uppsala, Sweden.
: Not applicable
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.