Science only works if we have the whole story. This is especially important in clinical trials, where the results of these studies are used to guide medical practice. Unfortunately, getting the whole story can be difficult–there are strong incentives to bury negative results. This radically distorts the published information on treatment effectiveness.
How to fix this problem? Clinical trials registries–(hopefully) mandatory databases of *all* clinical trials (hopefully) with the data once complete. Sounds easy, right? Unfortunately, implementing this straightforward idea has been surprisingly difficult and time-consuming.
At the Sackler colloquium I (Bob) attended in early March, Roberta Scherer reviewed the history of clinical trials registries. It stretches back much further than I realized, as shown in this graph Scherer presented from Dickersin & Rennie (2012):
There has been progress during this long history–clinical trials databases are now available for researchers throughout the world, they are being increasingly used, and some journals have successfully implemented and monitored processes to require registry prior to publication. Unfortunately, as we have discussed, there is still lots of work to do. Compliance remains low in some fields, the information in the registry is often incomplete, sharing of the data still is not uniform, and researchers often end up reporting their work in ways that differ from their registered protocols without noting the change (see this older post on the COMPARE project led by Ben Goldacre). Finally, only 54% of registered trials are not published–which is good because now this is discoverable, but bad because it means synthesizing the literature would still require trolling this partial and incomplete registries to try to scrape together the whole story. Still a long, long way to go.
Dickersin, K., & Rennie, D. (2012). The evolution of trial registries and their use to assess the clinical trial enterprise. Jama, 307(17), 1861–4. https://doi.org/10.1001/jama.2012.4230