Received: 25 March 2019
Accepted: 19 July 2019
First Online: 14 August 2019
Ethics approval and consent to participate
: The study was performed in accordance with the Helsinki Declaration, and the protocol was approved by the Regional Ethics Committee South-East Norway (reference number REK Sør-Øst D 2013/1023) and the institutional ethics committee of the Akershus University Hospital, Lørenskog, Norway. Informed consent was obtained from all individual participants included in the study.
: Not applicable.
: The authors declare that they have no competing interests.