Assessed as up to date: 2007/11/07
Informed consent is a critical component of clinical research. Different methods of presenting information to potential participants of clinical trials may improve the informed consent process. Audio-visual interventions (presented for example on the Internet, DVD, or video cassette) are one such method.
To assess the effects of providing audio-visual information alone, or in conjunction with standard forms of information provision, to potential clinical trial participants in the informed consent process, in terms of their satisfaction, understanding and recall of information about the study, level of anxiety and their decision whether or not to participate.
We searched: the Cochrane Consumers and Communication Review Group Specialised Register (searched 20 June 2006); the Cochrane Central Register of Controlled Trials (CENTRAL), The Cochrane Library, issue 2, 2006; MEDLINE (Ovid) (1966 to June week 1 2006); EMBASE (Ovid) (1988 to 2006 week 24); and other databases. We also searched reference lists of included studies and relevant review articles, and contacted study authors and experts. There were no language restrictions.
Randomised and quasi-randomised controlled trials comparing audio-visual information alone, or in conjunction with standard forms of information provision (such as written or oral information as usually employed in the particular service setting), with standard forms of information provision alone, in the informed consent process for clinical trials. Trials involved individuals or their guardians asked to participate in a real (not hypothetical) clinical study.
Data collection and analysis
Two authors independently assessed studies for inclusion and extracted data. Due to heterogeneity no meta-analysis was possible; we present the findings in a narrative review.
We included 4 trials involving data from 511 people. Studies were set in the USA and Canada. Three were randomised controlled trials (RCTs) and the fourth a quasi-randomised trial. Their quality was mixed and results should be interpreted with caution.
Considerable uncertainty remains about the effects of audio-visual interventions, compared with standard forms of information provision (such as written or oral information normally used in the particular setting), for use in the process of obtaining informed consent for clinical trials. Audio-visual interventions did not consistently increase participants' levels of knowledge/understanding (assessed in four studies), although one study showed better retention of knowledge amongst intervention recipients. An audio-visual intervention may transiently increase people's willingness to participate in trials (one study), but this was not sustained at two to four weeks post-intervention. Perceived worth of the trial did not appear to be influenced by an audio-visual intervention (one study), but another study suggested that the quality of information disclosed may be enhanced by an audio-visual intervention. Many relevant outcomes including harms were not measured. The heterogeneity in results may reflect the differences in intervention design, content and delivery, the populations studied and the diverse methods of outcome assessment in included studies.
The value of audio-visual interventions for people considering participating in clinical trials remains unclear. Evidence is mixed as to whether audio-visual interventions enhance people's knowledge of the trial they are considering entering, and/or the health condition the trial is designed to address; one study showed improved retention of knowledge amongst intervention recipients. The intervention may also have small positive effects on the quality of information disclosed, and may increase willingness to participate in the short-term; however the evidence is weak. There were no data for several primary outcomes, including harms. In the absence of clear results, triallists should continue to explore innovative methods of providing information to potential trial participants.
Further research should take the form of high-quality randomised controlled trials, with clear reporting of methods. Studies should conduct content assessment of audio-visual and other innovative interventions for people of differing levels of understanding and education; also for different age and cultural groups. Researchers should assess systematically the effects of different intervention components and delivery characteristics, and should involve consumers in intervention development. Studies should assess additional outcomes relevant to individuals' decisional capacity, using validated tools, including satisfaction; anxiety; and adherence to the subsequent trial protocol.
Ryan Rebecca, Prictor Megan, McLaughlin Kristin J, Hill Sophie
Audio-visual presentation of information used in the informed consent process for people considering entering clinical trials
Informed consent is important for people who are thinking about participating in a clinical trial. Information for informed consent could be presented on the Internet, DVD, video cassette or by other means.
We conducted thorough searches for randomised and quasi-randomised controlled trials of information about trial participation that contained some audiovisual component compared with standard information (such as written or oral information as usually provided in the particular setting). We found four relevant studies, all set in the USA and Canada. The four studies varied in terms of the design and type of the audio-visual information, its content and delivery, the people participating in the informed consent study and the different ways of measuring outcomes. While study quality was mixed, three of the studies attempted to minimise at least some sources of potential bias.
Uncertainty remains about the effects of audio-visual information for informed consent, compared with standard forms of information provision, for people thinking about participating in a clinical trial. All four studies assessed knowledge and/or understanding of the trial to which people's informed consent was being sought. Audio-visual interventions did not consistently increase participants' levels of knowledge/understanding, although one study showed better retention of knowledge amongst intervention recipients. One study showed that an audio-visual intervention could briefly increase people's willingness to participate in trials, but this was not sustained two to four weeks post-intervention. The audio-visual intervention did not affect people's views of the worth of the trial they were considering joining (one study). Another study found that an audio-visual intervention may enhance the quality of the information conveyed to participants. Many outcomes including possible harms were not measured.
Implications for practice
The value of audio-visual interventions as a tool for helping to improve the informed consent process for people considering participating in clinical trials remains unclear and requires additional research. Evidence is mixed as to whether audio-visual interventions enhance people's knowledge of the trial they are considering joining, and/or the health condition the trial is designed to address; one study showed improved retention of knowledge amongst intervention recipients. The intervention may also have small positive effects on the quality of information disclosed, and willingness to participate; however again the evidence is weak. There is at present no evidence of harm, although a range of important outcomes, such as anxiety, were not assessed. In the absence of clear results, triallists should continue to explore innovative methods of providing information to potential trial participants during the informed consent process, and should consider tailoring the interventions to particular participant groups.
Implications for research
The effects of audio-visual interventions for use in the informed consent process for trials remain unclear: four small trials, each with methodological limitations, reported mixed effects on a small range of outcomes. Further rigorous research is needed. Future studies should conduct content assessment of video and other innovative informational interventions for people at differing levels of understanding and education; also for different age and ethnic groups, in different settings and countries. Offering individual participants a choice of formats for informed consent information should also be evaluated; as should tailored interventions for use in the informed consent process for different participant groups.
Triallists should investigate which delivery components of an audio-visual intervention for informed consent make it more or less effective, systematically assessing the effects of different elements such as timing, provider and duration. Ideally, consumers should be actively involved in developing the intervention.
Future studies should include adequate outcome measurement, including the validation and reliability testing of all outcome measures. Studies should assess a range of outcomes in order to assess decisional capacity of potential trial participants, preferably using validated measures of informed consent, and including the consumer-oriented outcomes that were not assessed by included studies, such as: participant (or guardian) satisfaction with 1) information provided about the clinical study, 2) the media used to convey the information, and 3) the decision making process; anxiety; adherence with the study protocol; and withdrawal from the subsequent study following consent.
Triallists should seek to minimise the risk of bias in their studies by ensuring adequate randomisation and allocation concealment, and by blinding (where possible) participants, intervention providers and outcome assessors. Study reporting in this field also requires improvement; trial authors should adhere to the recommendations of the CONSORT statement (www.consort-statement.org), particularly in terms of the methods they use to minimise the risk of bias, and in terms of participant numbers and the flow of participants through each stage of the trial.
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