aRegional Centre of Excellence in Palliative Care, Haukeland University Hospital, Bergen, Norway
bPerioperative, Intensive Care and Pain Medicine, Pain Clinic, Helsinki University Hospital, University of Helsinki Helsinki, Finland
Sponsorships or competing interests that may be relevant to content are disclosed at the end of this article.
Received February 01, 2019
Accepted February 06, 2019
Online date: May/June, 2019
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