Consent Form Reporting on ClinicalTrials.Gov, 2013-2023

Informed consent documentation is legally, ethically, and scientifically imperative for research and provides prospective trial participants key study information. Historically, consent documents have been difficult to obtain and not consistently publicly available.¹ As of July 21, 2019, and after a 2-year voluntary period, the revised Common Rule required select federally funded interventional trials to publicly post consent forms no later than 60 days after the last participant visit.² The revision intends to increase research transparency and inform consent development. Although transparency efforts addressing trial registrations and results are well studied, less is known about public availability of consent forms in the context of the revised rule’s recent implementation.^3-6 This cross-sectional analysis examined National Institutes of Health (NIH)–funded trial consent form availability on ClinicalTrials.gov.

On October 26, 2023, we performed a search for NIH-funded interventional studies with completion dates between August 1, 2013, and August 1, 2023 (ie, a 10-year period of studies with a completion date 60 business days prior), on ClinicalTrials.gov. We exported the resulting 11 202 records. In alignment with the revised rule, only trials with closed recruitment statuses were included (eg, active not recruiting, completed, and terminated). We reviewed records for availability of consent forms and manually extracted the dates forms were posted. Studies were categorized by completion date into 3 periods: prevoluntary, voluntary, and revised rule. The revised rule period refers to when posting for select trials was mandated. The voluntary period refers to the 2-year grace period leading up to the revised rule in which posting of consent was explicitly voluntary and, therefore, distinct from the prevoluntary period. We used a 2-sided t test to estimate the difference in the mean annual percentage of studies with consent forms posted before and after the revised rule’s implementation. Statistical analyses were performed using R statistical software version 4.2.3 (R Project for Statistical Computing), and P < .05 was considered statistically significant. This study used public, nonidentifiable data that did not constitute human participants research (45 CFR §46.102) and did not require institutional review board review. The study followed STROBE reporting guidelines.

Of 10 311 trials included in the final sample, 1716 (16.7%) posted consent forms (Table 1). Among studies completed in the prevoluntary period, 105 (2.7%) posted consent forms. The mean percentage of studies posting annually increased from 13.8% during the voluntary period to 30.5% after the revised rule (difference, 16.7 percentage points; 95% CI, 5.6 percentage points to 27.1 percentage points; P = .01). Across the 1716 studies with consent forms, the median (IQR) time between study completion and posting was 201.0 (14.0 to 392.3) days, with 617 (36.0%) posting within 60 days (Table 2). The median (IQR) time to posting improved from 1040.0 (378.0 to 2218.0) days in the prevoluntary period to 364.5 (204.0 to 703.5) days during the voluntary period. After the revised rule, median (IQR) time to posting decreased to 103.0 (−14.0 to 346.0) days (Table 2).

In this cross-sectional study examining NIH-funded trials on ClinicalTrials.gov over the course of a decade, consent form availability improved over time, yet time to posting often exceeded 60 days even after the revised rule (Table 2). This may indicate that investigators post consent forms when regulations require results be made available (eg, 1 year after completion). Study limitations include not being able to verify which trials were subject to the revised rule, which studies required participant consent, and whether consent forms were available on other federal websites. However, including only NIH-funded interventional studies mitigates these limitations. Importantly, consent documents narrow trial information down to what is most relevant for prospective participants and is often the only document written for participants. Public availability of consent documents could impact trial recruitment; therefore, making these forms available to prospective participants while trials are still active should be considered.

Accepted for Publication: April 25, 2024.

Published: June 21, 2024. doi:10.1001/jamanetworkopen.2024.18895

Open Access: This is an open access article distributed under the terms of the CC-BY License. © 2024 Axson SA et al. JAMA Network Open.

Corresponding Author: Sydney A. Axson, PhD, MPH, Ross and Carol Nese College of Nursing, Pennsylvania State University, 201 Nursing Sciences Bldg, University Park, PA, 16802 (saaxson@psu.edu).

Author Contributions: Drs Axson and Giordano had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: Axson, Giordano.

Acquisition, analysis, or interpretation of data: Axson, Ramachandran, Lisenby.

Drafting of the manuscript: Axson, Giordano.

Critical review of the manuscript for important intellectual content: All authors.

Statistical analysis: Axson, Lisenby.

Administrative, technical, or material support: All authors.

Supervision: Axson, Giordano.

Conflict of Interest Disclosures: Dr Ramachandran reported receiving grants from Arnold Ventures, Stavros Niarchos Foundation, and US Food and Drug Administration (FDA); receiving personal fees from ReAct-Strategic Policy Program for a consultancy that ended in 2022; and serving as Board President for Universities Allied for Essential Medicines (North America) and as Chair of the FDA Task Force for Doctors for America outside the submitted work. Dr Giordano reported receiving grants from the National Institute on Drug Abuse and the National Football League outside the submitted work. No other disclosures were reported.

Data Sharing Statement: See the Supplement.

Additional Contributions: Tatiana Getz, BS (Emory University), Selma Selimovic, MPH (Emory University), Karolus Wangi, MS (Pennsylvania State University), and Julie Zhu (Emory University) assisted with reviewing trial records and extracted informed consent document data. No additional compensation was provided.