Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
First published online: 8 November 2018, Int J Epidemiol, doi: https://doi.org/10.1093/ije/dyy238
In the originally published version of this article, the first and last names of the authors Angela Balkwill and Ai Seon Kuan appeared in the wrong order. This has now been corrected.
