The SRA Symposium - College of Medicine

Papers
Readability vs Comprehension: Grade level recommendations assume that consent forms written at
a 6th- 8th grade level will be more understandable than those written at a college grade level. Unfortunately,
that assumption isn’t supported by the evidence. A 2004 review (Hochhauser, 2004b)
of comprehension of hard-to-read original documents vs easy-to-read revised documents found
only small improvements in reader understanding, perhaps an improvement of about 10%-15%
in understanding. But even that degree of improvement was weakened by the way comprehension
was measured. Of the nine studies reviewed, only two addressed the validity and reliability of the
comprehension measures. Unless such measures are shown to be both valid and reliable, their reliance
on “face validity” is scientifically meaningless. Equally important is that comprehension was
often measured by true-false or multiple choice questions. But true-false measures suffer from the
limitation that since there are only two choices, a respondent can get half the answers correct by
guessing; multiple choice questions have a similar problem, insofar as a question with four choices
can be answered correctly 25% of the time by guessing. With such scientifically weak comprehension
measures, the assumption that the recommended 6th- 8th grade consent form will significantly
increase comprehension over a 14th grade consent form remains to be proven.
Writing at a 6th-8th grade level: Even if the recommended goal for a consent form is a 6th-8th
grade reading level, reaching that goal will be difficult, if not impossible. Because readability formulas
calculate grade level based on the average number of words in a sentence and the average
number of syllables in a word, the only way to get a consent form down to a 6th-8th grade level is
to write shorter sentences with fewer words. Flesch’s Reading Ease score (Flesch, 1949) estimates
that documents written at a 6th-8th grade reading level will average 14-17 words per sentence and
139-147 syllables per 100 words. Given technical language of a typical consent form, it’s unlikely—if
not impossible—to write consent forms at that recommended level. Writers can “write to the
formula” (e.g., changing one long sentence into three shorter sentences) but readability researchers
do not recommend that strategy because it often results in shorter, but choppier sentences that
don’t communicate very well and might not improve comprehension. Paradoxically, consent forms
written at a statistically more “readable” level may not be more “understandable.”
The Subject
Understanding informed consent: Because research shows that documents rewritten to lower grade
levels do not improve comprehension very much, it’s crucial to ask what comprehension means
to both researchers and prospective subjects. What researchers communicate isn’t always what’s
understood.
As noted above, consent form comprehension studies show that consent forms written at lower
grade levels don’t improve comprehension very much. But because of study limitations, even those
small improvements may not generalize to understanding informed consent in the clinical trial
setting. While those studies that found some improvement in comprehension with consent forms
written at lower grade level, those studies often used consent forms that were fairly brief, anywhere
from 300 to 1,000 words, while Sharp’s (2004) analysis of oncology consent forms found them
to average eleven pages and about 2,700 words. But it may be worse than that. Sharp’s analysis
only included the typical informed consent form—not the newer consent forms that often include
HIPAA information. Although the FDA does not require HIPAA information to be part of
the consent form which would require it to be reviewed by the IRB, many sponsors have added
HIPAA information to the consent form instead of including it as an addendum—which does not
have to be reviewed by the IRB. Additional HIPAA information can add another 500-900 words
to the consent form, making the typical oncology consent form about 3,500 words long—over ten
times as long as some consent forms in the comprehension studies.
2005 Symposium Proceedings Book 107