Barbour, VFlanagan, DTairi, K2022-10-052022-10-052022-10-05BMJ 2022;379:o2334, DOI: http://dx.doi.org/10.1136/bmj.o23341756-1833https://hdl.handle.net/10292/15500All Research articles published by The BMJ are published by default as open access (irrespective of who funded the research) and reuse is permitted in accordance with the terms of the relevant applicable open access licence.Journal ArticleOpenAccess10.1136/bmj.o2334