The contents and readability of informed consent forms for oncology clinical trials

To compare the quality of informed consent forms (ICF) for different trial phases, funding sources, oncology subspecialties, disease settings, and intervention modalities.

ICF for prospectively conducted clinical trials were examined for their descriptions of benefits and risks, study alternatives, voluntary participation, and confidentiality. Readability was assessed with Flesch Reading Ease (FRE) score and Flesch-Kincaid Reading Grade Level.

Among 262 evaluable trials, ICF contained an average of 3982 words, 379 sentences, and 10.5 pages. The mean FRE score and Reading Grade Level were 61.2 and 7.4, respectively. All ICF explicitly stated that the intervention was investigational. Only 2 (1%) promised direct personal benefits, 16 (6%) suggested the chance of cure or prolonged survival, and 89 (34%) indicated a potential for tumor response. Conversely, 239 (91%) mentioned the risk of serious harms, 217 (83%) admitted that some side effects could be unknown or unpredictable, and 126 (48%) reported hospitalization or death as a possibility. Alternatives to participation, right to withdraw from study, and data confidentiality were addressed in 242 (92%), 254 (97%), and 260 (99%) ICF, respectively. Hematology, industry-funded, metastatic, and systemic therapy trials were most likely to highlight major risks (P < 0.05). Readability was better in phase I trials and in studies, which were performed by medical oncologists, sponsored by governmental agencies, conducted in the metastatic setting, and involved systemic therapy (P < 0.05).

ICF had acceptable readability and provided a realistic overview of the benefits and risks of clinical trials, but the potential for hospitalization or fatality was underreported.