Background Public information on US clinical trials is shared through the ClinicalTrials.gov registry. This study’s goal was to determine prospective registration, results reporting, trial registration number reporting, and publication accessibility status for trials with primary completion dates from 2014 to 2017 affiliated with seven California universities.

Methods We identified trials with investigators, sponsors, or responsible parties affiliated with seven California universities and searched for their results publications manually. We then used semi-automatic methods to determine prospective registration, summary results reporting in a registry, publication status, and reporting of registration numbers in the abstract and the full text of manuscripts.

Results We identified 1,091 unique trials. Most trials were single-center (n=752, 69%) and had a median of 50 participants (IQR 21 to 150). Overall, 64% of trials (n=698) were prospectively registered, 46% (n=500) had summary results reported in the registry, 69% (n=750) had results published as articles, and an additional 3% (n=36) as abstracts or posters. Results reporting (summary, articles, abstracts or posters) occurred for 58% of trials (n=637) within 2 years, and for 81% (n=888) within 5 years of study primary completion date. Of journal publications, 77% (n=579) were open access publications, 37% (n=276) had trial registration numbers listed in their abstract, and 45% (n=336) in the manuscript. Only 92 (8%) of these trials were legally required to report results, and only 2 (2%) of those were overdue and under primary responsibility of a California university to report.

Conclusions Almost one fifth of clinical trials with primary completion dates from 2014 to 2017 with investigators, sponsors or responsible parties affiliated with seven California biomedical research universities lacked any results reporting 5 years after their primary completion, and only 58% reported results within 2 years. Even though a large majority of these trials were completed before US legal mandates for reporting, there was an ethical requirement that the burden to research participants should be commensurate with the scientific value of the research. Research has no public scientific value if its results are not reported.

MM and SNG are employed by Stanford University which is one of the universities whose trials were analyzed in this study. DS served as a member of the Sanofi Advisory Bioethics Committee until 2022 and received an honorarium for contributing to meetings.

Emmanuel Zavalis received a travel grant from Carl Erik Levins stiftelse for his fellowship at METRICS. The work of the BIH team was funded by intramural funds from Berlin Institute of Health (BIH) at Charite - Universitstsmedizin Berlin, Germany. Work of Mario Malicki and Steven N. Goodman was supported by the Stanford School of Medicine Research Office.

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

Yes

I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

Yes

I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

Yes

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Per CREDIT taxonomy:

Mario Malički: Conceptualization, Data curation, Formal Analysis, Investigation, Methodology,

Project administration, Visualization, Writing – original draft, Writing – review & editing.

Susanne Wieschowski: Investigation, Methodology, Project administration

Stefanie Gestrich: Investigation, Writing – review & editing.

Nicole Hildebrand: Investigation, Writing – review & editing.

Samruddhi Yerunkar: Investigation, Writing – review & editing.

Emmanuel Zavalis: Investigation, Writing – review & editing.

Benjamin Gregory Carlisle: Data curation, Methodology, Software, Writing – review & editing. Vladislav Nachev: Data curation, Software, Writing – review & editing.

Maia Salholz-Hillel: Conceptualization, Data curation, Methodology, Software, Writing – review & editing.

Delwen L. Franzen: Conceptualization, Data curation, Methodology, Software, Writing – review & editing.

Steven N. Goodman: Conceptualization, Methodology, Supervision, Writing – review & editing.

Daniel Strech: Conceptualization, Funding acquisition, Methodology, Project administration, Resources, Supervision, Writing – original draft

Code Availability: The code used for the initial query of registry data via AACT is available at https://github.com/maia-sh/california-trials, Statistical results output are deposited at Stanford Digital Repository: https://doi.org/10.25740/gq169sj2027

Data Availability: The initial registry data from the AACT is available at https://github.com/maiash/california-trials. The final dataset used for analysis is available at https://github.com/ontogenerator/california-clinical-dashboard/tree/main/data.

Disclaimer: None.

Funding: Emmanuel Zavalis received a travel grant from Carl Erik Levins stiftelse for his fellowship at METRICS. The work of the BIH team was funded by intramural funds from Berlin Institute of Health (BIH) at Charité – Universitätsmedizin Berlin, Germany. Work of Mario Malički and Steven N. Goodman was supported by the Stanford School of Medicine Research Office.

Ethics Approval: No ethics approval was needed as we analyzed publicly available data.

Presentations at meetings/conferences: None.

Preprint availability: This is the first preprint version of the study.

Protocol and analysis plan availability: The study protocol and its analysis plan are available at: https://osf.io/u9d5c/.

Reporting: This study was reported following the Strengthening of the Reporting of Observational Studies in Epidemiology (STROBE) guidelines.