Informed Consent Forms (ICFs) are an essential component of research involving human subjects. ICFs provide participants with general information about the study, participant expectations, risks/benefits, compensation/expenses and privacy safeguards. In an effort to provide additional information for ethical and legal purposes, the length of ICFs have significantly increased over recent decades (Albala, Doyle & Appelbaum, 2010; Kass, et al, 2011; Corneli & Sugarman, 2017).
The increasing lengths of ICFs is a concern to researchers, since it is correlated with a reduction in participant understanding of pertinent information included within the ICF. Some research has concluded that the relationship between ICF length and negative outcomes is causal in nature. These findings have validated such concerns, finding a link between ICF length and participant understanding, with shorter ICFs leading to higher levels of comprehension (Beardsley, Jefford & Mileshkin, 2007; Beardsley et al., 2007; Dresden & Levitt, 2001; Enama, Hu, Gordon, Costner, Ledgerwood & Grady, 2012; Stunkel et al., 2010).
However, there is a substantial body of literature that challenges these findings, which calls into question the causal relationship between ICF length and the impact on participant outcomes. This body of research contends that participant understanding and comprehension is not directly caused by the length of the ICF. Rather, negative participant outcomes including participant understanding, concerns, trust, satisfaction and consent rates are poor regardless of ICF length (Grady, et al., 2017; Matsui, et al., 2012). One prominent theory for poor outcomes is the desensitization of participants towards the content of ICFs due to overexposure to legal disclaimers, such as terms of service, which are more frequently encountered in recent years.
While outcomes of participants appear to be independent of the ICF length, scholarship has also dissected the relationship between ICF structure and comprehension. The inclusion of particular elements (or the format) of the ICF does not have a demonstrable effect on comprehension or response rates (Perrault & Keating, 2018). That being said, participants do have preferences on the inclusion and exclusion of certain elements. The areas of the most concern for participants are foreseeable risks, direct benefit and adverse effects. The areas of least concern are remuneration, conflicts of interest and funding sources (Karbwang, et al., 2018). Participants also prefer ICFs that are more concise, while disgruntled by “repetitive”, “too detailed” and “laborious” information (Corneli, et al., 2017). Research has also found that participants favor the use of highlighting (Perrault & Keating, 2018) and utilizing bullet points, bold text and shorter sentences. However, the use of highlight and bold text should be selective and limited to individual words or phrases as opposed to entire sentences or paragraphs (Priestly, 1991).
In summary, the literature is in agreement that more concise ICFs and the inclusion of certain stylistic elements are preferred by respondents, even if they do not result in statistically significant improvements in comprehension, consent rates or response rates compared to longer ICFs. It should also be noted that the research cited herein varied drastically in their definitions of “concise” and “standard”, with “concise” ICFs ranging from 2 pages to 16 pages. With respect to style, there is a consensus about emphasizing sections that are unique to the particular study being conducted and using appendices and/or aggregation as a method of shortening the ICF.