Improving participant comprehension in the informed consent process

Purpose: To critically analyze studies published within the past decade about participants' comprehension of informed consent in clinical research and to identify promising intervention strategies. Design: Integrative review of literature. Methods: The Cumulative Index of Nursing and Allied Health Literature (CINAHL), PubMed, and the Cochrane Database of Systematic Reviews and Cochrane Central Register of Controlled Trials were searched. Inclusion criteria included studies (a) published between January 1, 1996 and January 1, 2007, (b) designed as descriptive or interventional studies of comprehension of informed consent for clinical research, (c) conducted in nonpsychiatric adult populations who were either patients or volunteer participants, (d) written in English, and (e) published in peer-reviewed journals. Findings: Of the 980 studies identified, 319 abstracts were screened, 154 studies were reviewed, and 23 met the inclusion criteria. Thirteen studies (57%) were descriptive, and 10 (43%) were interventional. Interventions tested included simplified written consent documents, multimedia approaches, and the use of a trained professional (consent educator) to assist in the consent process. Collectively, no single intervention strategy was consistently associated with improved comprehension. Studies also varied in regard to the definition of comprehension and the tools used to measure it. Conclusions: Despite increasing regulatory scrutiny, deficiencies still exist in participant comprehension of the research in which they participate, as well as differences in how comprehension is measured and assessed. No single intervention was identified as consistently successful for improving participant comprehension, and results indicated that any successful consent process should at a minimum include various communication modes and is likely to require one-to-one interaction with someone knowledgeable about the study.