There is global acceptance that individuals should be allowed to decide whether or not to take part in research studies, and to do so after being informed about the nature of the research and the risk that might attach to participation. The process of providing detailed information before seeking consent (formalized by signatures) in advance of undertaking research procedures may not be possible in some circumstances, and sometimes an amended approach may be adopted. The use of opt-out consent has been recognized as a valid and ethical means of recruiting participants to studies particularly with large samples and where the risk to participants is small. However, it is sometimes misunderstood and can be a problematic factor in being accepted by research ethics committees and governing authorities. This may be due partly to differing expectations of the amount of information and support offered, together with the nature of the process that is adopted to ensure that a decision has been made rather than consent simply being assumed. In accordance with ongoing discussions with young people, and following consultation with parents, an opt-out consent strategy including varied means of providing information was employed in a large study of 44,501 cases of children attending emergency or urgent care departments. The study was conducted over more than 12 months in dissimilar emergency departments and an urgent care unit, and was designed to support better decision-making in pediatric emergency departments about whether children need to be admitted to hospital or can be discharged home safely. Robust analysis of the factors that exerted the greatest impact on predicting the need to admit or the safety of discharging children led to a revised version of an existing tool. In this article, we review approaches to consent in research, the nature and impact of opt-out consent, the factors that made this an effective strategy for this study, but also more recent concerns which may make opt-out consent no longer acceptable.
Keywords: Emergency department; children; ethics; opt-out consent; research.