Background: Randomised controlled trials of healthcare interventions depend on the participation of volunteers who might not derive any personal health benefit from their participation. The idea that altruistic-type motives are important for trial participation is understandably widespread, but recent studies suggest considerations of personal benefit can influence participation decisions in various ways.
Methods: Non-participant observation of recruitment consultations (n = 25) and in-depth interviews with people invited to participate in the UK REFLUX trial (n = 13).
Results: Willingness to help others and to contribute towards furthering medical knowledge featured strongly among the reasons people gave for being interested in participating in the trial. But decisions to attend recruitment appointments and take part were not based solely on consideration of others. Rather, they were presented as conditional on individuals additionally perceiving some benefit (and no significant disadvantage) for themselves. Potential for personal benefit or disadvantage could be seen in both the interventions being evaluated and trial processes.
Conclusions: The term 'conditional altruism' concisely describes the willingness to help others that may initially incline people to participate in a trial, but that is unlikely to lead to trial participation in practice unless people also recognise that participation will benefit them personally. Recognition of conditional altruism has implications for planning trial recruitment communications to promote informed and voluntary trial participation.
Trial registration: ISRCTN15517081.