Introduction Little is known about how adolescents’ attitudes about willingness to participate (WTP) in clinical trials change over time.

Methods Adolescents (14–17 years) were asked two times about WTP for a hypothetical microbicide safety trial a year apart. After rating their WTP at follow-up, the adolescents were asked how their thoughts about the study had changed. They were not reminded of their previous WTP response; qualitative coding of responses was blinded to their WTP.

Results The adolescents (n=294) were 69% Hispanic, 63% female, and had a mean age at baseline of 15.5 years. Most (60%) adolescents reported that their thoughts had stayed the same, 33% reported a change, which might or might not be associated with a perceived change in WTP, and 7% stated that they did not remember. Some adolescents reported understanding the study information better; either it had been explained better or they paid greater attention. This was not always associated with a perceived change in WTP. Others reported a change in the weight of the information, either for non-specific reasons or because of new experiences (I had a yeast infection and they did the whole exam thing and it wasn’t that bad) or new information (in high school I’ve learned about it). Others attributed changes to maturation/age (I think I’m older and I can focus more) or to a personality change (e.g. less shy). Parental impact included a few who reported an influential conversation with a parent (I know more because my parents have been talking about it) or the ability to make an independent decision.

Conclusion Most adolescents did not report a change in thinking. Some did not feel they had all the information the first time; for others, their attitudes about the information changed. For a few, independence from parents led to a change. Adolescents should be given continued opportunities to participate in clinical research over time. Future research should explore ways to ensure that adolescents understand key information to make the best decision, and to balance parental guidance with autonomy.

Support: National Institutes of Health (R01HD067287); National Centre for Advancing Translational Sciences, National Institutes of Health (UL1 TR000040, UL1 TR000457)