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Clinical trials: what a waste

BMJ 2014; 349 doi: (Published 10 December 2014) Cite this as: BMJ 2014;349:g7089
  1. John P A Ioannidis, professor and director1, co-director2
  1. 1Stanford Prevention Research Center, 1265 Welch Road, Medical School Office Building, Room X306, Stanford, CA 94305, USA
  2. 2Meta-Research Innovation Center at Stanford (METRICS),
  1. Correspondence to: J P A Ioannidis jioannid{at}

Trials that are unregistered, unfinished, unpublished, unreachable, or simply irrelevant

Randomized controlled trials are the gold standard tool for evaluating interventions. Nevertheless, the utility of this excellent tool is contingent on how it is used. Chapman and colleagues (doi:10.1136/bmj.g6870) show this in a sample of 395 trials relevant to surgical practice that were registered in between 2008 and 2009.1 By the end of 2013, 21% were discontinued, 34% of those that were completed were not published, and for 77% of the trials that had uncertain fate no way existed to reach investigators to find what had happened to them. This work adds to several other empirical evaluations showing that evidence from randomized controlled trials is wasted at multiple stages from conception to publication and beyond.2 3 4 5 6 7 8 9 10 11 12

Many trials are entirely lost, as they are not even registered. Substantial diversity probably exists across specialties, countries, and settings. Overall, in a survey conducted in 2012, only 30% of journal editors requested or encouraged trial registration.2

Among registered trials, a sizeable fraction are never completed. In some cases, discontinuation may be the best …

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