The gastrointestinal clinical trial landscape: A cross-sectional analysis of clinicaltrials.gov from 2007-2019.
Authors: Perera Nirosha , Kamceva Marija , Shen Jolie Z. , Song Siyou , Steinberg Jessica , Turner Brandon E. , Shyu Margaret , Gao Jing , Khan Ali T. , Dhanani Zainub , Mahipal Amit 
Published: January 2021

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Background: The burden of gastrointestinal (GI) disease is high, costing over $97 billion annually in the United States (U.S.) alone. Yet the methodological rigor and characteristics of trials leading to guideline development are rarely explored. In 2007, the U.S. mandated that all interventional studies (Phase II-IV) register with ClinicalTrials.gov, the largest international clinical trial database. We characterized registered GI trials to identify features associated with early discontinuation, results reporting and increased methodological rigor. Methods: We employed a cross-sectional study design with descriptive, logistic regression, cox regression, time series and survival analyses. We downloaded data for 327 075 studies registered on the Aggregate Analysis of the ClinicalTrials.gov database from October 1, 2007 to December 31, 2019. Trials were excluded if registered prior to 2007 (n=38 111) or for non-interventional study design (n=69 233). After applying GI specific Medical Subject Heading terms to the remaining 219 731 trials, 22 339 trials were identified for manual review. 20 548 trials were found to contain true GI content, representing over seven million patients. Primary exposure variables were trial focus (disease process, anatomical location) and funding (industry, U.S. government, academic). Results: Of the 20 548 GI trials, 6.1% were funded by the U.S. government, 35.6% by industry, and 58.3% by academic institutions. The most studied disease process was neoplasia (42.6% of trials), followed by viral hepatitis (10.8%). The majority of neoplasia trials were funded by academic institutions (60.3%) and studied colorectal neoplasms (31.5%), followed by hepatic (17.9%), pancreatic (15.5%), gastric (12.8%), esophageal (10.6%) and biliary tract (4.9%) neoplasms. U.S. government funded trials had the lowest risk of early discontinuation (adjusted Hazard Ratio 0.63, 95% CI: 0.48-0.83, p<0.001) and the highest rates of results reporting (25%, X2 p<0.001). Among all trials, the majority did not report Data Monitoring Committee (DMC) oversight (58.6%). Only 12% of phase III trials employed a rigorous methodology, which we defined as being randomized, double blinded, multi-site, overseen by a DMC, and having enrolled ≥50 patients. Government sponsored trials had the highest proportion of trials meeting this definition (19%). Academic sponsored trials, constituting the majority of trials overall, had the lowest proportion (5.3%), in part due to not meeting the multi-site criteria. Conclusions: Despite constituting the minority of trials overall, U.S. government funded trials displayed the highest methodological rigor. Stakeholders can look to U.S. government funded trials as a model of improvement, but nevertheless must commit to increasing methodological rigor and results dissemination to strengthen trial findings that guide GI clinical recommendations.