Improved informed consent documents for biomedical research do not increase patients’ understanding but reduce enrolment: a study in real settings

Abstract

The aim was to evaluate the comprehension of participants of an improved informed consent document (ICD). This was a randomized controlled French multicentre study performed in real conditions. Participants were adult patients undergoing screening for enrolment in biomedical research studies, who agreed to answer a validated questionnaire evaluating objective and subjective comprehension scored from 0 (no comprehension) to 100 (excellent comprehension). Patients were provided either the original ICD or an ICD modified in terms of structure and readability. The primary end point was the score of objective comprehension. The secondary end-points were the enrolment rate in the clinical study and patient characteristics associated with the score of objective comprehension. Four hundred and eighty-one patients were included, 241 patients in the original ICD group and 240 patients in the modified ICD group. There was no difference between the two groups for the score of objective comprehension (original ICD 72.7 (95% CI 71.3, 74.1) vs. modified ICD 72.5 (95% CI 71.0, 74.0); P = 0.81). However, the rate of enrolment in the clinical study was lower in the group who received the modified ICD (64.4% (95% CI 58.3, 70.5)) than for the original ICD (73.0% (95% CI 67.4, 78.7)) (P = 0.042). Only female gender and high educational level were associated with a better objective comprehension. Improving ICDs had no effect on participants' understanding, whereas the rate of enrolment was lower in this group. In attempts at improving potential participants' understanding of clinical research information, efforts and future trials should focus on other ways to improve comprehension.