Although the consent process for a clinical trial is intended to ensure that potential participants understand that they are participating in research, as well as the risks, benefits, study procedures and alternatives to enrollment in the study [4
], data show that participants have variable levels of understanding of study information [10
]. At the same time, clinical research consent forms have become increasingly long and complex [2
]. The data from this study of consent forms indicate that the healthy adult participants in these vaccine trials had a similar level of understanding of study information and similar satisfaction with the length and complexity of the consent form regardless of whether they received a standard consent form or a concise form that had about a 63% reduction in the number of words. Those who received the concise form were more likely to report feeling very well informed and that the staff had explained the study to them very well. The evidence from this study is consistent with the hypothesis that a simpler more concise form will not affect comprehension of key study information. Of note, our goal was not to evaluate if a concise consent would improve comprehension. Vaccine study participants at this clinic routinely have a high level of understanding of the research, and the majority of healthy adults who volunteered had at least a college level education. The concern raised about research using a concise consent form was that subjects would be at risk of harm because of insufficient information about research study participation. Although it is logical to assume that the length and complexity of the consent form may affect participant comprehension of the study and satisfaction with the experience, the direction of that effect is unknown, and very few randomized studies have investigated the influence of the length and complexity of consent forms on understanding. It is also possible that the form itself has much less to do with comprehension than multiple discussions with research staff. We did not attempt to evaluate the contribution of discussion to consent comprehension and satisfaction since clearly all subjects must be allowed to ask questions and receive information from qualified clinical site staff.
Common policies and procedures related to consent form content and format that have developed over years within research institutions are the basis for standard practices in clinical research. These reflect an experience-based consensus about what constitutes an adequate consent process for participation in clinical research. To develop a truly evidence-based consensus about best practices for consent to clinical research, data evaluating outcomes of different aspects of the consent process in diverse groups of participants need to be collected and validated. The study reported here is part of a larger endeavor to investigate strategies of improving the informed consent process overall and evaluating consent forms in particular. One goal is to develop more concise and simpler consent forms that are acceptable to IRBs and clinical researchers and shown to be effective at informing study participants in the context of a properly conducted consent process.
As part of the larger consent project initiated through the NIH Clinical Center Department of Bioethics to study the length and complexity of consent forms, the study published by Stunkel, et al reported results from using different length consent forms in a low risk, bioequivalence study of a marketed drug in healthy volunteers in a different setting. Similar to the findings in our study, they reported no evidence of an effect on comprehension or satisfaction by using a concise consent. They also noted that their findings may not be generalizable to Phase I studies of investigational products [6
]. Likewise, we recognize that the study results reported here may not be generalizable to other clinical trial circumstances. This comparative investigation of consent forms was conducted at a single site with only 111 healthy adult participants. The participants had high education levels and a little more than half had prior experience with research. It was not expected to be a definitive study, but rather to contribute to the development of approaches to studying consent forms and to the publicly available data on consent form comprehension and satisfaction. We recognize that highly experienced research staff routinely use consent practices that contribute to comprehension of the study apart from the consent form itself. However, despite being limited to a specific type of Phase I setting, our consent form study does serve as a next step in evaluating the consent process when standard and concise consents are used. Research by others, including a study comparing concise and standard consent forms for participants in a cancer research study, also found little difference in understanding when participants were given consent forms of different lengths, but found a participant preference for the concise form. This study is not directly comparable to ours as among other factors, the subjects were not randomized to the consent forms, the two consent reading levels (12th
grade vs 5th
grade) represented a greater difference in reading level, and the consent study participants were not actual candidates for the study for which the consents were written. [12
]. Investigating the use of concise forms in an even greater diversity of clinical trials settings is important to fully address the study hypothesis.
Given these observations to date, one might ask why bother to make the consent form simpler and more concise if consent forms of different lengths result in similar levels of comprehension, as hypothesized. In our study, neither the length of time it took for subjects to read the consent form nor the reading ability of participants was measured, although the study participants overall had a high educational level. Other published data suggest that the concise consent at approximately 2000 words would likely take an adult with average reading skills 8–10 minutes to read, while the standard consent at approximately 5000 words would likely take 20–25 minutes to read [13
]. Data collected in other spheres of research show that more people read and understand information that is presented in a shorter format [14
]. It might be presumed that the less time it takes to read a consent form the more likely it is that it will be read and understood. The greatest potential benefit of a concise form is likely to be for participants with more limited reading abilities than our well-educated cohort. But everyone involved in the research process, including IRB staff, researchers, subjects of all educational and reading abilities, and regulatory agencies would benefit from shorter forms in terms of greater efficiency in review time, storage, printing and processing.
The Office for Human Research Protections has called for greater transparency of consent form content towards the goal of improving the quality of consent forms and the associated consent process [15
]. Results reported here support continuing an evidence-based approach to evaluating both the consent form and the process. Continued investigation of strategies to improve research informed consent is critical and such research should be supported by IRBs towards widely shared goals of developing consistent and high quality consent forms for participation in clinical trials. The accumulated experience to date is that randomizing study participants to a standard or concise consent is an acceptable approach when both the study and the consent forms used are IRB-approved, and there is no evidence of harm by using a shorter consent form or from studying the consent process. Investigation of consent length in multicenter studies with larger numbers of participants, participants more likely to misunderstand aspects of the study, and with participants who have a greater diversity of educational levels are recommended as next steps, in conjunction with continuing exploration of other strategies to improve comprehension and the quality of consent to participate in clinical trials.