- Correspondence to Dr David I Swedler, University of Illinois at Chicago, School of Public Health, 2121 W Taylor St, Chicago, IL 60612, USA;
- Received August 14, 2014
- Revised January 12, 2015
- Accepted February 2, 2015
- First published February 20, 2015.
This web only file has been produced by the BMJ Publishing Group from an electronic file supplied by the author(s) and has not been edited for content.
Files in this Data Supplement:
- Data supplement 1 - Online supplement
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.