Received: 13 November 2018
Accepted: 10 January 2019
First Online: 6 March 2019
Ethics approval and consent to participate
: Patients registered in the SpineData registry were invited to give their written informed consent for their data to be used for research purposes. Only patients who had given their written consent were included in this study. The Scientific Ethics Committee of Southern Denmark has found that this type of study is exempted from ethics approval (project ID S-200112000-29). The registry is registered with the Danish Data Protection Agency (2008-58-0035). The study complies with the Declaration of Helsinki.
: Not applicable.
: The authors declare that they have no competing interests.
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