Failed Randomized Clinical Trials in Radiation Oncology: What Can We Learn?
Abstract
PURPOSE
Randomized clinical trials (RCTs) are essential to evidence-based medicine, yet a significant proportion fail to be completed. In radiation oncology, factors contributing to trial failure are not well understood. We sought to compare completed and incomplete clinical trials involving radiation therapy (RT) to identify predictors of trial failure.
METHODS AND MATERIALS
We undertook a review of ClinicalTrials.gov to identify RCTs involving RT. Eligible trials mandated external beam RT in ≥1 arm of the study and were registered between September 27, 2007, and December 31, 2010. Univariate and multivariate logistic regression analyses were performed to determine factors predictive of trial failure.
RESULTS
We included 134 eligible studies, of which 94 (70.1%) were successful and 40 (29.9%) failed. The reasons for trial failure were categorized as follows: lack of accrual (57.5%), inadequate funding (15.0%), drug unavailability (7.5%), interim data-monitoring report recommendations (7.5%), and other (12.5%). Over time, significantly more trials were failing to be completed (P = .010), with rates increasing from 11.8% (before 2007) to 34.0% (2007-2008) to 39.5% (2009-2012). On univariate analysis, predictors of failure were trials with a surgical comparator (odds ratio [OR], 8.12; P = .013), government sponsorship (vs non-government; OR, 3.67; P = .025), inclusion of a safety endpoint (OR, 2.85; P = .022), and studies starting after 2006 (P = .033). On multivariate…
How strong is the evidence?
Evidence Hub reads this as a randomized trial, done in people. Its evidence level is 2 of 5 (High · randomized trial). Randomized trials of a reasonable size are the strongest single-study design.
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