Evidence indicates that research participants often do not fully understand the studies for which they have volunteered. The aim of this systematic review was to examine the relationship between the process of obtaining informed consent for research and participant comprehension and satisfaction with the research.

Systematic review of published research on informed consent and participant comprehension of research for which they volunteer using the Preferred Reporting Items for Systematic Review and Meta‐Analysis (PRISMA) Statement as a guide.

PubMed, Cumulative Index for Nursing and Allied Health Literature, Cochrane Central Register of Controlled Trails, and Cochrane Database of Systematic Reviews were used to search the literature for studies meeting the following inclusion criteria: (a) published between January 1, 2006, and December 31, 2013, (b) interventional or descriptive quantitative design, (c) published in a peer‐reviewed journal, (d) written in English, and (e) assessed participant comprehension or satisfaction with the research process. Studies were assessed for quality using seven indicators: sampling method, use of controls or comparison groups, response rate, description of intervention, description of outcome, statistical method, and health literacy assessment.

Of 176 studies identified, 27 met inclusion criteria: 13 (48%) were randomized interventional designs and 14 (52%) were descriptive. Three categories of studies included projects assessing (a) enhanced consent process or form, (b) multimedia methods, and (c) education to improve participant understanding. Most (78%) used investigator‐developed tools to assess participant comprehension, did not assess participant health literacy (74%), or did not assess the readability level of the consent form (89%). Researchers found participants lacked basic understanding of research elements: randomization, placebo, risks, and therapeutic misconception.

Findings indicate (a) inconsistent assessment of participant reading or health literacy level, (b) measurement variation associated with use of nonstandardized tools, and (c) continued therapeutic misconception and lack of understanding among research participants of randomization, placebo, benefit, and risk. While the Agency for Healthcare and Quality and National Quality Forum have published informed consent and authorization toolkits, previously published validated tools are underutilized.

Informed consent requires the assessment of health literacy, reading level, and comprehension of research participants using validated assessment tools and methods.