Introduction: In England, everyone is considered an organ donor unless they have registered for opt-out donation. Research Question: This study evaluated positive statements and negative affective attitudes against anticipated organ donor status and whether the order in the attitudes and statements presented impacted organ donor intention under an opt-out system. Design: A quasi-experimental mixed between-within design was employed with participants assigned to 1 of 2 conditions. Participants in the first condition received negative affective attitude statements followed by positive statements. This was reversed in the second condition to combat ordering effects. Participants (N = 679) were asked about their donor status under an opt-out system. There were three groups: opt-in (actively), opt-out/not sure, and deemed consent (no objection). Organ donor intentions were measured at three intervals: baseline, post-positive statements, and post-negative attitudes. Results: Approximately 10% of participants would opt-out or were unsure of their intentions to be an organ donor under an opt-out system. Significant effects were found in both positive statements and negative affective attitudes. All groups expressed greater medical mistrust and were most influenced by cognitive attitudes. Conclusions: Under the opt-out system in England, it is anticipated that the majority would actively opt-in or have no objection to being automatically registered as an organ donor. Public health campaigns would benefit from promoting the most influential positive statements and refuting the most detrimental negative attitudes to increase intentions of those who plan to opt-out or are unsure.
Keywords: affective attitudes; health behaviours; opt-out system; organ donation.