Text and Data Mining valid from 2019-09-24
Received: 28 May 2019
Accepted: 11 September 2019
First Online: 24 September 2019
Ethics approval and consent to participate
: The study was approved by the local ethics committee (EK 071/11 and EK 277/12) and is in accordance with the declaration of Helsinki on ethical principles for medical research involving human subjects.
: Not applicable.
: The authors declare that they have no competing interests.