Liu, LFeigin, VSacco, RLKoroshetz, WJ2020-10-122020-10-1220202020BMJ 2020;371:m37531756-18331756-1833https://hdl.handle.net/10292/13714No abstract.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/.Journal ArticleOpenAccess10.1136/bmj.m3753