Clinical trials : journal of the Society for Clinical Trials
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Randomized Controlled Trial
Parent perspectives on consent for the linkage of data to evaluate vaccine safety: a randomised trial of opt-in and opt-out consent.
We examined parents' consent preferences and understanding of an opt-in or opt-out invitation to participate in data linkage for post-marketing safety surveillance of childhood vaccines. ⋯ This trial demonstrates that informed consent for a population-based surveillance programme cannot realistically be achieved using mail-based opt-in and opt-out approaches. While recall and understanding of the study's purpose were better among parents who actively consented (opted in) compared with parents who passively consented (did not opt out), participation was substantially lower (21% vs. 96% respectively). Most parents appeared to have a poor understanding of data linkage for vaccine safety surveillance; nonetheless, they supported data linkage. They preferred a system utilising opt-out consent or no consent to one using opt-in consent.