. 2015 Apr 1;350:h1603. doi: 10.1136/bmj.h1603
© Nerland et al 2015
This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.
Fig 1 Flow diagram with study enrolment and follow-up