Any study including human subjects should properly inform participants before obtaining informed consent. To date, few studies have investigated to what extent participants truly comprehend all the information before signing the ICF. Additionally, since it has been shown that an ICF alone is not sufficiently good at conveying information, new methods to do so are needed. Our study aimed at testing different interventions (pamphlet alone, information session alone or both) and measuring their impact on the caregivers of participants’ knowledge. We found that the information session had a positive impact on caregivers’ understanding of the clinical trial, but receiving a pamphlet did not.
The lack of effect of the pamphlet on the caregivers’ understanding could be related to the fact that although the majority of caregivers received and read it, they did not understand it. Also, caregivers in the pamphlet only group did not have the opportunity to ask questions before being interviewed, unlike the other two intervention groups. Finally, caregivers meant to receive the pamphlet may have shown it to those not meant to receive it, diluting its effect. Hence, our finding indicates that a pamphlet might not always be an appropriate communication tool. The impact of a communication tool differs among cultural settings so different methods should be tested in different regions. In many African settings oral communication is given more value than written communication, most likely due to the low literacy levels, particularly in adults [18]. Alternative forms of conveying information such as slide shows, theaters, videos and songs have been shown to be more effective than written formats [19]. It would be useful if GCP would provide guidance on the best ways to deliver information during the informed consenting process since most clinical researchers do not have formal training in social, anthropological or communication sciences. These recommendations should be tailored for different settings.
In contrast, having attended an information session increased the proportion of correct answers given to most questions and these increases were significant for half of the questions. Most of these questions were either related to the parasite (hookworm) or to the trial design (procedures). For example, compared to caregivers who did not attend an information session, those who did knew significantly more often that their child did not have to provide a urine sample or pay for treatment and that they would need to provide a small blood sample (finger prick). Also, they were more knowledgeable concerning the mode of transmission of hookworm and its consequences on health. It is worth highlighting that in this study we had 12 information sessions of rather small size allowing us to increase engagement with caregivers. To minimize any confounding due to the speaker of the information session, the same person led every session and its content was standardized across sessions.
However, three important facts about our clinical trial were worryingly misunderstood by caregivers, even after an information session. First, although about half of the caregivers understood why we were conducting this clinical trial (to find the most effective regimen of mebendazole against hookworm), 30% responded it was because this drug had never been used before. Second, 53% of caregivers thought that their child cannot withdraw from the study once they had accepted to participate. Lastly, 62% of parents reported that nothing bad could happen after receiving treatment (the correct answer was that the drug may have some mild side effects such as abdominal pain or a headache). Our results are in line with those reported in a systematic review about informed consent comprehension in African research settings, which documented that only approximately half of caregivers understood the right to withdraw and the risks involved [10]. Thus, our results show that, although caregivers received these key messages during an information session, their comprehension was low. One reason could be that this format of transferring knowledge is not the most appropriate for communicating this type of information, particularly in a context where health literacy remains limited. Therefore, it is important to explore other formats of transmitting key messages of a clinical trial using pictures, videos or even theaters. Previous studies have shown that, for example, the use of videos significantly increases participants’ comprehension when compared to a standard informed consent procedure [20,21,22]. Another potential explanation for the poor understanding of caregivers might be related to the concept of “authority of knowledge”, i.e. caregivers may feel it is not their job to understand these issues or judge their legitimacy, consequently leaving the decision in the hands of people who truly know the subject. Therefore, it is possible that caregivers choose to trust the research staff, the teachers’ decision to support the study, the ethics committee approving the trial and the government allowing such studies to take place in their communities instead of making a real effort to understand themselves [23]. Further studies would be necessary to better understand “how much information is too much information?” in the context of a clinical trial in these settings and whether caregivers indeed feel that they do not need to truly understand the study background [24].
Additionally, some questions were answered correctly by most caregivers, regardless of which group they belonged to, i.e. having attended an information session was not the reason why they responded correctly. It seems to be known that treatment for hookworm exists, that caregivers should be the ones deciding whether their child participates in the trial or not, that the research staff will treat children still found infected at follow-up, that the child is asked for several stool samples during the study, that the child should let a doctor know how he/she is feeling after treatment, and that a child should accept a doctor’s physical examination.
Several limitations of our study are worth highlighting. First, the randomization was not conducted in a consistent manner. Although children were initially randomly assigned to receive the pamphlet or not, insufficient caregivers due to lack of adherence and insufficient children infected with hookworm, led to alternating distribution of the pamphlet in an attempt to balance both groups. Second, parents were assigned to each of the groups (with or without information session upon the interview) depending on their time of arrival to the information session classroom. Parents arriving first were immediately interviewed. However, parents who reached the study site first might have been more interested in the study and, therefore, possibly more knowledgeable. If this was the case, there could be some bias decreasing the effect of the information session. Third, because we were working in a single school, we could not avoid knowledge contamination between groups. It is likely that caregivers who attended some of the first information sessions talked to caregivers who had not yet attended an information session, sharing some of their newly acquired knowledge. This way, the effect of the information session may have become less apparent. Moreover, it would have been interesting to study the effect of the caregivers’ gender on understanding, documented in previous studies [25, 26], but gender was not recorded in our study. Likewise, checking for caregivers’ literacy levels would have been useful for the interpretation of our particular results. Finally, it has been shown that closed-ended questionnaires assessing knowledge tend to overestimate the participants’ understanding of informed consent information. Thus, future studies could consider including either open-ended questions or allow for spontaneous answers to avoid influencing participants’ responses [27].
