Earlier this year, a study in PloS Medicine found that nearly one-third (30%) of a sample of randomized controlled trials (RCTs) had been discontinued prematurely, a number that had not improved over the previous decade. Furthermore, for every 10% increase in adherence to SPIRIT protocol reporting guidelines, RCTs were 29% less likely to go unpublished (OR: 0.71; 95% confidence interval: from 0.55 to 0.92), and only about 1 in every 5 unpublished trials had been registered.
Now, in this month's issue of Journal of Clinical Epidemiology, Schönenberger and colleagues have released a study of the availability of RCT protocols from a sample of published works.
Public availability of study protocols, the authors argue, improves research quality by promoting thoughtfulness in methodological design, reducing selective outcomes reporting or "cherry-picking," and reducing the misreporting of results while promoting ethical compliance. This is especially the case when trial protocols are made available before the publication of study results.
From a random sample of RCTs approved by ethics committees in Switzerland, Germany, Canada, and the United Kingdom in 2012, the authors examined the proportion of studies that had publicly available protocols and the nature of how the protocols were cited and disseminated. Of the resulting 326 RCTs, 118 (36.2%) had publicly available protocols. Of the protocols, nearly half (47.5%) were available as standalone peer-reviewed publications while 40.7% were available as supplementary material with the published results. A smaller proportion (10.2%) of protocols were available on a trial registry.
Studies with a sample size of >500 or that were investigator- (non-industry)-sponsored were more likely to have publicly available protocols. The nature of the intervention (drug versus non-drug) did not appear to affect protocol availability, nor did whether the trial was conducted in a multicenter or single-center setting. The majority (91.8%) of protocols were made available after the enrollment of the first patient, and just 2.7% were made available after publication of trial results. Protocols were commonly published shortly before the trial results, at a median of 90% of the time between the start of the trial and its publication.
As this sample comprised only RCTs published in 2012 and by relatively high-income countries, it is unclear whether public protocol availability has improved over time or may be different in other global regions. However, the authors argue, these numbers lend credence to the need for efforts to improve the public availability of RCT protocols, such as through trial registries or requirements by publishing or funding bodies.
Schönenberger, C.M., Griessbach, A., Heravi, A.T., et al. (2022). A meta-research study of randomized controlled trials found infrequent and delayed availability of protocols. J Clin Epidemiol 149:45-52. Manuscript available at publisher's website here.