Background: A primary concern of clinical trials is the protection of subjects, which is part of the voluntary consent process. However, the issues regarding informed consent, including the patients' lack of understanding of trials due to the complexity of informed consent documents (ICDs), continues to be debated. This study was conducted to determine the current state and issues of ICDs using the quality standards of Decision Aid (DA), as a basis for developing DAs for trials.

Methods: ① Two independent evaluators assessed 20 ICDs using the quality of decision-making parameters (DQ standards). The evaluation was based on a two-point scale. ② Semi-structured interviews were conducted with 16 stakeholders. The interview contents were categorized and analyzed per the DQ standards domains.

Results: The evaluation of ICDs revealed that more than half of the forms contained insufficient information required for good quality decision-making. The interviews also showed similar results, a predominantly negative opinion toward ICDs, and concerns about the neutrality of explanations provided by the medical staffs.

Conclusion: Existing ICDs may not be useful for good-quality decisions. Results suggested the following need to be addressed for good-quality decision-making for clinical trial participation: a more precise delineation between participation and non-participation, a correct comprehension and interpretation of numerical information about trials, and think about what matters most to patients, neutral decision support. Therefore, it is necessary to develop DAs based on these results.