Received: 27 September 2017
Accepted: 8 February 2018
First Online: 28 February 2018
Ethics approval and consent to participate
: Ethical permission for data collection for PCBaSe is covered by ref. 2013–153-31 provided by the Research Ethics Board at Umeå University. Ethics for data collection in the Singapore cohort is covered by CIRB ref. 2009/1053/D approved by the Singhealth Centralised Institutional Review Board.
: Not applicable. No patient identifiable data was used or is presented.
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.