Supplementary Material for: Recall and Retention of Consent Procedure Contents and Decisions: Results of a Randomized Controlled Trial

Background: Residual tissue samples, i.e., samples excised for diagnosis or during treatment, are commonly used for medical research. In the Netherlands, they can be used provided the patient did not opt out of this use. Previous research has shown that recall of the informed consent procedure for tissue use is poor. Here, we investigate recall of three consent procedures: informed consent, opt-out, and opt-out plus (an opt-out procedure with an information procedure similar to that of informed consent). Methods: Patients (n = 1,319) with a variety of diseases were randomized into three trial arms: informed consent, opt-out plus, and opt-out. Questionnaires were administered 6 weeks and 6 months after randomization. Results: Six hundred and seventy-three and 553 patients returned the 6-week and 6-month questionnaire, respectively. In the informed consent arm, recall of having received a brochure (55.3%) or oral information (69.4%) was similar to that in the opt-out plus arm (48.5 and 71.6%, respectively), at the 6-week assessment. Significantly more respondents in the informed consent and the opt-out plus arms versus the opt-out arm recalled that they had been informed about being able to control tissue use and which consent procedure they had experienced (6-week questionnaire range 53.2–75.8 vs. 13.9–16.1%; 6-month questionnaire range 43.5–84.2 vs. 3.2–35.4%). There were no significant differences between the informed consent and opt-out plus arms in this regard. Conclusions: Recall of the consent procedure was similar in opt-out plus and informed consent procedures. Overall, recall was moderate, indicating that there is room for improvement in the quality of information provision.