Randomized study of two different consent procedures on recall: a study within a digital alcohol intervention trial

Individuals' comprehension of the information provided in consent forms should fundamentally influence whether to participate initially in a study and later whether to remain a participant. Existing evidence, however, suggests that participants do not thoroughly read, comprehend, or recall the information in consent forms. This study aimed to better understand how well participants recalled trial procedure information in the consent materials they received prior to taking part in a trial of a digital alcohol intervention.

This study was nested within an online effectiveness trial. The study included a contrast between two layout approaches to present the trial procedure information: one where all materials were shown on the same page (One page) and one where participants had to click on links to get materials for certain parts of the study information (Active request). Recall of trial procedures was measured 2 months post-randomization with four questions. Participants were also asked to leave a comment after each question.

Of the 2437 individuals who registered interest in the parent trial, 1197 were randomized to One page and 1240 were randomized to Active request. Approximately 90% consented to participate and 53% of the participants responded to the recall questionnaire. Contrasting the consent layout showed no marked differences between groups in three out of the four questions on recall of trial procedures. There was, however, evidence that recall of aspects of how personal data would be handled during the trial did differ between the two groups, with the Active request group reporting less recall than the One page group. Free-text comments were used to give nuance to the quantitative analysis.

Participants exposed to different layouts of trial procedure information exhibited varying levels of information recall 2 months after consenting. The findings highlight the influence of the presentation of consent forms, which should be given attention when designing trials.

ISRCTN ISRCTN48317451. Registered 6 December 2018, https://www.isrctn.com/ISRCTN48317451.