Received: 19 April 2016
Accepted: 19 February 2018
First Online: 27 February 2018
Ethics approval and consent to participate
: This cohort study used non-identifiable information from routinely collected administrative healthcare datasets in Scotland and had approval from the NHS National Services Scotland Privacy Advisory committee (ref: PAC 36/14).
: Approval to use anonymous routinely collected patient data has been obtained as described above.
: The authors declare that they have no competing interests.
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