Funding for this research was provided by:
Economic and Social Research Council, ESCR (ES/L015471/1)
Received: 9 October 2019
Accepted: 28 November 2019
First Online: 9 December 2019
Ethics approval and consent to participate
: Approval for the use of anonymised data in this study, provisioned within the Secure Anonymised Information Linkage (SAIL) Databank was granted by an independent Information Governance Review Panel (IGRP) under project 0336. The IGRP has a membership comprised of senior representatives from the British Medical Association (BMA), the National Research Ethics Service (NRES), Public Health Wales and NHS Wales Informatics Service (NWIS). Usage of Welsh Health Survey data was approved by Welsh Government. The use of anonymised data for research is outside the scope of the EU General Data Protection Regulations (GDPR) and the UK Data Protection Act.
: Not applicable
: The authors declare that they have no competing interests.