Different types of intervention to improve research consent across a variety of settings show mixed impact on improving participant knowledge. The search and data abstraction for this paper adds twenty-four interventions, tested in randomized control trials, to Flory and Emanuel’s 2004 systematic review. In addition, this first of its kind meta-analysis, notwithstanding the stated limitations, demonstrates that enhanced consent forms, extended discussion, and multimedia interventions favor improved knowledge outcomes. Only enhanced consent forms and extended discussion interventions were significant in changing the outcome; the consistency of multimedia’s effectiveness remains unclear. Finally, there is little evidence that a participant’s satisfaction or a study’s accrual rates would be negatively altered by attempts to improve the informed consent process, which should be reassuring to investigators. Our findings confirm those from other previously performed systematic reviews. However, they may not be applicable to illiterate or socially disadvantage groups, given the limits of our search, indicating an important domain for more research.
Our data highlight several key points. First, both the form and the conversation are important for the process.Secondly, the effect of multimedia in the informed consent process remains in question. However, as found in the 2004 review, it may prove useful in helping with long-term knowledge retention . This element of learning may promote other dimensions of participant autonomy such as voluntariness: if a participant better remembers what a study is about, he or she can better decide whether to stay enrolled. Moreover, we speculate that multimedia may serve to compliment discussion and written forms to simultaneously address immediate and long-term understanding. Defining the role of multimedia will be increasingly critical as media-based technology becomes cheaper to implement, more accessible and more transportable (e.g., iPads).
Still, even the most exquisitely-designed form, be it on paper or computer screen, should not be expected to suffice. Arguably there is still no substitute for a good conversation, which facilitates opportunities for questions and interaction cannot be underestimated. An interesting and novel focus for improving consent could be creating interventions designed explicitly on improving communication skills Our data suggest that if the research enterprise could move towards a practice of rich conversations between investigator and participant, several crucial points would be addressed. Participants may have a better understanding of the study, they would likely feel more like a “partner” in the research process, they could be easily exposed to a natural test/feedback setting, and a relationship between the participant and the researcher would be established. We found that extended discussions had the most consistent result of improving understanding, although only 50% showed significant improvement. No category of intervention managed to have consistent efficacy.
The question of whether “shorter forms are better than longer forms” – at least whether “shorter is no worse than longer” for participant understanding – is still an open question, pointing to the need for studies that directly compare a “short form” intervention to a traditional “long form” control in a randomized control setting. Whether short forms coupled with conversation would potentiate even greater increases in understanding is a hypothesis for future consent research.
The efficacy of test/feedback interventions is difficult to discern at this point. Most test/feedback trials fall easily into the format of a pseudo-randomized or cohort study as only the participants who fail a first assessment proceed to take a second (or third) assessment. Researchers must devise more stringent methodologies to ensure that their studies are fully legitimate randomized experiments.
Our study has several limitations. We restricted our search to interventions tested in RCT trials in order to meet the general gold standard of a systematic review. Yet, others have suggested that certain complex, socially-embedded biomedical activities are restricted by the lens of an RCT . The informed consent process may be such an activity and may find ample aid from other more qualitative or observational studies. In addition, our study is limited by the primary outcome we sought to investigate: understanding. We were focused on objective assessments of participant understanding. Rates of understanding are important under the presumption that more information aids potential participants in decision-making . Information-based decision-making aims to demonstrate respect for individual participants’ autonomy.However, there are other ethical values that may be equally, if not more, important to participants. For example, the values of trust and honesty may be more significant to participants who are willing to enter a trial based on their physicians’ recommendations. Truly informed consent may thus entail more than simply comprehending and memorizing information.
Several features of our analysis reveal the need for standardized research on informed consent interventions. The controls used in the studies we analyzed were highly varied. In some studies the control consent process was similar to standard practice. Usually, this process involved a long, paper-based document at the 12th grade (or higher) reading level . In other studies, the control was an already enhanced version of the standard form. For example, Mittal et al.’s control form was a well-designed, formatted brochure revised to read at the 8th grade reading level . One would expect the improvements in understanding—over the control—for trials with enhanced control formats to be less significant than those with standard control formats. In some cases, the control cohort did not have any form, likely amplifying the results of the intervention . Thus, side-by-side comparison of these different interventions may be unfair.
Heterogeneity across these trials was the norm for assessing understanding. The wide ranges in normalized scores for both control and intervention between studies suggest that the varied choice of approach across studies may contribute to perceived level of understanding. While all trials included are interested in a participant’s level of understanding after the consent process, the different testing formats produced varied results. Assessments differed drastically in format, question-type, length, and provision and this heterogeneity among assessments hinders direct comparison. Standardized, verified examinations have been developed specifically for the informed consent process, yet only several studies in our review made use of them. For example, the MacCAT-CR, BICEP and QuIC are all pre-established assessment tools that were used in several studies [19, 31, 48]. However, the majority of studies used custom-created assessment forms. While a number of teams determined the reliability of their tests through pilot versions or other means, the inconsistency between different trials still precludes an accurate comparison. Just as the composition of an informed consent document may impact understanding levels, so too may assessment methods impact the degree to which participants can express their knowledge. This issue is particularly relevant for populations with low-literacy levels. Comparing results between trials with strongly divergent assessment techniques is problematic and limits the value of systematic reviews.
Additional variations between studies that limit comparison have been discussed by previous authors. The categories with the most positive outcomes, enhanced discussion and test-feedback, were also the categories with the fewest number of studies . Few adequate criteria exist for tracking study quality; there are vast differences between population demographics; and categories for interventions group disparate interventions together. In 2009, Henry et al. focused in depth on each study in Flory and Emanuel’s multimedia category, exposing how almost every study could be interpreted differently than it was in the systematic review. They agreed with the authors of a Cochrane review of multimedia informed consent interventions: “the empirical literature is not yet sufficiently developed to draw definitive conclusions one way or the other about the general effectiveness of or value derived from multimedia consent aids” [11, 61]. We agree with this conclusion of Henry et al. and Ryan et al. and further extended its implications to include all of the intervention categories. Perhaps more important than our findings for improving the consent process are our findings for improving the study of the consent process.
Despite these limitations and potential theoretical flaws, our research contributes an important body of data to the study of understanding in the informed consent process.