Zelen randomization: attitudes of parents participating in a neonatal clinical trial.
Recruitment to randomized controlled trials can be difficult for all parties involved. An alternative to the standard process has been suggested for trials in which the control group receives standard treatment or nontreatment. In this approach (the Zelen design), randomization precedes consent, which is only sought from those allocated to the experimental arm of a trial. The control group is thus unaware that randomization has taken place. As a controversial method, this approach has been often suggested but rarely used. Here we describe how 44 parents recruited to a difficult neonatal trial that used conventional randomization reacted to the idea of Zelen randomization. The arguments they gave for and against the method pertain to four areas: the giving or withholding of information, the effect on decision making, the use of data without parental knowledge, and the long-term impact for parents. The parents were evenly divided in accepting or rejecting the method. Further analysis showed that those rejecting Zelen randomization were more likely to be parents of infants allocated to the control group. This suggests that those from whom consent would not be sought, the group that this approach is primarily meant to protect, are most likely to find it unacceptable.