Received: 10 August 2019
Accepted: 16 December 2019
First Online: 21 January 2020
Ethics approval and consent to participate
: The study was approved by the regional ethical review board in Stockholm, Sweden (Dnr 2007/371–31/3).
: Not applicable.
: LA has received a research grant from CSL Behring. UH, AW, AÖ, JS, MW and AÅ report no competing interests.