Randomized, Double-Blind Trial on the Impact of Word Count in Cancer Clinical Trial Consent Forms

This randomized, double-blind study sought to understand whether cancer clinical trial consent form verbosity detracts from patients' decision making on trial enrollment.

This trial tested mock consent forms of 2,000, 4,000, and 6,000 words. The first two comprised the two experimental arms and the third the control arm. Phase II was conducted to identify the promising arm, which, in phase III, was compared with the control arm. Each consent form described the same trial. Eligible adult patients reported a cancer history and English literacy. The primary end point used a patient-reported Likert scale to assess the relationship between information in the consent form and trial decision making.

In phase II, 93 patients were accrued and prompted the selection of the 2,000-word consent form for phase III. In phase III, 182 patients were recruited, resulting in 240 total evaluable patients to compare the 2,000-word versus the 6,000-word arm (control). For the primary end point, 103 (84%) and 107 (91%) patients in the 2,000- and 6,000-word arms, respectively, strongly agreed or agreed with the following: "The information in this consent form helped me make a decision about whether or not to enroll in the trial" (two-sided, P = .14). Median time to read each consent form was 8 and 12 minutes, respectively (two-sided, P < .0001). Among those assigned these consent forms, 84% and 73%, respectively (two-sided, P = .04) signed or expressed a willingness to sign.

This study's primary end point was not met. However, secondary outcomes suggest a need to further study the efficiency and efficacy of shorter consent forms for cancer clinical trial enrollment.