Consent Forms, Lower Reading Levels, and Using Flesch-Kincaid Readability Software

Abstract

The US Food and Drug Administration requires the use of a consent form as part of the protection of human subjects in clinical trials. To help increase the probability of consent form comprehension, the biopharmaceutical industry, FDA, National Cancer Institute, and National Institutes of Health often advise developing consent forms between a sixth and eighth grade reading level. Prior studies have examined consent comprehension at different reading levels. However, prior study results are often inconsistent, do not all utilize consents conforming to the Code of Federal Regulations (CFR), and do not all report the validity or reliability of the comprehension measurement tool used or the studies’ sample populations that are homogeneous and possess limiting characteristics. Thus the question remains whether lowering the reading level of a CFR-conforming consent form increases comprehension in a population devoid of predefined characteristics. Also unanswered is whether other variables, together or separately, such as age, gender, income level, and prior exposure to consent forms affect comprehension of consent forms written at different reading levels. To establish baseline research regarding the comprehension-reading level relationship, a study was performed utilizing a heterogeneous population of individuals waiting for jury service. The effects on comprehension by age, income, gender, prior exposure to consent forms, and 6th versus 10th grade reading level consents were examined. The consent forms’ reading levels were determined using the Flesch-Kincaid Grade Level scale in Microsoft Word. Comprehension was measured using a validated 15-question multiple-choice questionnaire that subjects completed after reading the consent forms. Statistical analysis of the effects by age and consent level on comprehension resulted in a significant main effect on comprehension by age, but no effect by consent level. A comparison indicated that only the 30–44 and 60–75 age groups demonstrated significant differences in comprehension. An analysis of the effects on comprehension by gender, income, and consenting to research in the past resulted in no significant main or interaction effects. Additional analysis confirmed that only age significantly affected comprehension. The research concluded that gender, income, prior exposure to consent forms, and lowering consent reading level had no effect on comprehension, and comprehension was only affected by age after the age of 60. This study also confirmed that when used as a preliminary tool, scanning a consent form using the Flesch-Kincaid Index in Microsoft Word can prove effective for developing consent forms.