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Article History

Received: 18 January 2017

Accepted: 22 February 2018

First Online: 5 March 2018

Ethics approval and consent to participate

: The study protocol was reviewed by the NZ Health and Disabilities Ethics Committee, with the ethics committee determining that ethical approval was not required. The NZ Ministry of Health granted data access, providing data with encrypted NHI numbers to maintain patient anonymity.

: Not applicable.

: The authors have no competing interests to declare.

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