Funding for this research was provided by:
Received: 27 September 2019
Accepted: 8 January 2020
First Online: 31 January 2020
Ethics approval and consent to participate
: This study was performed in accordance with the Declaration of Helsinki. Ethical approval was approved by the Regional Ethical Review Board (EPN) in Uppsala (ref.nr 2017/265). All participants gave their informed written consent to participate in the study, prior to data collection. Copies of signed consent forms can be provided on request.
: All participant gave written consent to publish individual patient data.
: HL and AR have received compensation from Nordic Drugs for giving lectures on chronic pain and opioids and AR has also lectured on chronic pain on behalf of Astra Zeneca. The remaining authors declare no competing interests.