Dataset Information

How frequently do the results from completed US clinical trials enter the public domain?--A statistical analysis of the ClinicalTrials.gov database.

ABSTRACT:

Background

Achieving transparency in clinical trials, through either publishing results in a journal or posting results to the ClinicalTrials.gov (CTG) web site, is an essential public health good. However, it remains unknown what proportion of completed studies achieve public disclosure of results (PDOR), or what factors explain these differences.

Methods

We analyzed data from 400 randomly selected studies within the CTG database that had been listed as 'completed' and had at least four years in which to disclose results. Using Kaplan-Meier curves, we calculated times from completion to PDOR (defined as publishing the primary outcomes in a journal and/or posting results to CTG), and identified explanatory variables predicting these outcomes using Cox proportional hazards models.

Findings

Among the 400 clinical trials, 118 (29.5%) failed to achieve PDOR within four years of completion. The median day from study completion to PDOR among 282 studies (70.5%) that achieved PDOR was 602 days (mean 647 days, SD 454 days). Studies were less likely to achieve PDOR if at earlier stages (phase 2 vs. phase 3/4, adjusted HR 0.60, 95% CI 0.47-0.78), if they only included adult subjects (adjusted HR 0.61, 95% CI 0.45-0.83), involved randomization (adjusted HR 0.62, 95% CI 0.46-0.83), or had smaller sample sizes (≤50 subjects vs. >50, adjusted HR 0.60, 95% CI 0.44-0.83). Industry-funded studies were significantly less likely to be published than non-industry or blended studies (adjusted HR 0.49, 95% CI 0.36-0.66).

Conclusions

A significant proportion of completed studies did not achieve PDOR within the four years of follow-up, particularly smaller studies at earlier stages of development with industry funding. This constitutes reporting bias and threatens the validity of the clinical research literature in the US.

SUBMITTER: Saito H

PROVIDER: S-EPMC4098992 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Background/aims The Food and Drug Administration Amendments Act mandates that applicable clinical trials report basic summary results to the ClinicalTrials.gov database within 1?year of trial completion or termination. We aimed to determine the proportion of pulmonary trials reporting basic summary results to ClinicalTrials.gov and assess factors associated with reporting. Methods We identified pulmonary clinical trials subject to the Food and Drug Administration Amendments Act (called highly likely applicable clinical trials) that were completed or terminated between 2008 and 2012 and reported results by September 2013. We estimated the cumulative percentage of applicable clinical trials reporting results by pulmonary disease category. Multivariable Cox regression modeling identified characteristics independently associated with results reporting. Results Of 1450 pulmonary highly likely applicable clinical trials, 380 (26%) examined respiratory neoplasms, 238 (16%) asthma, 175 (12%) chronic obstructive pulmonary disease, and 657 (45%) other respiratory diseases. Most (75%) were pharmaceutical highly likely applicable clinical trials and 71% were industry-funded. Approximately 15% of highly likely applicable clinical trials reported results within 1?year of trial completion, while 55% reported results over the 5-year study period. Earlier phase highly likely applicable clinical trials were less likely to report results compared to phase 4 highly likely applicable clinical trials (phases 1/2 and 2 (adjusted hazard ratio 0.41 (95% confidence interval: 0.31-0.54)), phases 2/3 and 3 (adjusted hazard ratio 0.55 (95% confidence interval: 0.42-0.72)) and phase not applicable (adjusted hazard ratio 0.43 (95% confidence interval: 0.29-0.63)). Pulmonary highly likely applicable clinical trials without Food and Drug Administration oversight were less likely to report results compared with those with oversight (adjusted hazard ratio 0.65 (95% confidence interval: 0.51-0.83)). Conclusion A total of 15% of pulmonary clinical highly likely applicable clinical trials report basic summary results to ClinicalTrials.gov within 1?year of trial completion. Strategies to improve reporting are needed within the pulmonary community.