Participants’ understanding of a randomized controlled trial (RCT) through informed consent procedures in the RCT for breast cancer screening, J-START

BACKGROUND: It is often difficult to enrol healthy volunteers into a randomized controlled trial (RCT) as there are barriers to participants’ proper understanding of a trial. This study aimed to evaluate degrees of understanding of the informed consent (IC) process among healthy volunteers who participated in an RCT. Additionally, factors associated with degree of understanding were investigated. METHODS: The J-START (the Japan STrategic Anti-cancer Randomized controlled Trial) is an RCT investigating the effectiveness of ultrasonography screening for breast cancer in women aged 40 to 49 years. To evaluate participants’ understanding of the J-START, we administered questionnaires to 376 Japanese women on the day of enrolment at five study sites across Japan. The respondents were asked to complete the anonymous questionnaire within 2 weeks. We assessed objective understanding and perceived subjective understanding of IC using a Japanese version of the Quality of Informed Consent scale (QuIC). Then we analyzed the characteristics of women whose understanding was poor, and clarified the association between providing information and their understanding of the study protocol. RESULTS: The average QuIC scores were 78.2 and 82.2 (out of 100 each) for objective and subjective understanding, respectively. These are generally acceptable scores for participants’ understanding of an RCT. However, there were four domains with low scores, indicating poor understanding: (1) experimental nature of the study, (2) potential risks or discomfort, (3) benefit to self, and (4) compensation. CONCLUSIONS: Healthy volunteers generally well understood the J-START. Nevertheless, there were some domains in need of improvement. In order to facilitate participants’ understanding, it is necessary to provide training to reduce differences in information-providing procedures between medical centres and to endeavour to provide consistent information and conditions. TRIAL REGISTRATION: The J-START was registered with the University Hospital Medical Information Network Clinical Trial Registration (UMIN-CTR), Japan (registration number: UMIN000000757), on July 1, 2007.