- Correspondence to Emma Knowles, Medical Care Research Unit, School of Health and Related Research, University of Sheffield, Sheffield S1 4DA, UK;
- Received July 14, 2015
- Revised December 21, 2015
- Accepted December 29, 2015
- First published February 12, 2016.
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.