Text and Data Mining valid from 2019-06-11
Received: 12 May 2019
Revised: 29 May 2019
Accepted: 30 May 2019
First Online: 11 June 2019
Compliance with ethical standards
: All authors have completed the ICMJE uniform disclosure form at ExternalRef removed and declare: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.
: This study used de-identified, routinely collected data and includes no identifiable or individual data in the manuscript. Ethical approval was therefore not required although internal peer-review by the SMSR steering committee and independent internal review by an NHS employed consultant of public health ensured the project was in line with the aims and objectives of the SMSR and consistent with usual public health practice for the use of routinely collected data obtained without explicit consent.