An official Cochrane policy. Last updated July 2004.
Cochrane is committed to providing the most reliable evidence of the effectiveness of health care through systematic reviews of randomised controlled trials (RCTs), and recognises the importance of prospectively registering trials to ensure that the evidence assessed is complete and unbiased.
Cochrane recommends that:
- all RCTs trials are registered at their inception (at the time of ethical approval and/or funding approval);
- registered information should be potentially accessible to all interested parties;
- registration should be with a register that complies with an appropriate minimum standard of practice;
- prospective registration of trials should be part of ethical guidelines for clinical trials;
- government agencies should ensure that adequate mechanisms and infrastructure are provided so that all RCTs can be registered prospectively;
- government agencies should explore legislative and other strategies to mandate prospective registration as a condition of, for example, funding, ethics or regulatory approval.
In addition, Cochrane supports:
- the principle of a global trials register;
- a unique international numbering system such as the ISRCTN (International Standard Randomised Controlled Trial Number) currently available through the organization Current Controlled Trials website;
- activities that facilitate the widespread adoption of this unique numbering system:
- If a fee is charged to obtain this unique number, and this fee is a significant barrier to obtaining a number, Cochrane encourages endeavours that would result in a reduction or removal of this fee;
- the comprehensiveness of the global trials register through the incorporation of the Cochrane Central Register of Controlled Trials (CENTRAL).
Cochrane recognises that the registration of trials at their inception will accomplish the following:
- Help identify health care strategies that require research, and set priorities for research in the light of concurrent studies in progress.
- Avoid unintentional duplication of clinical trials or allow replication of trials when appropriate.
- Foster collaboration between investigators considering similar trials.
- Assist recruitment to trials in progress.
- Allow patients and patient support groups to be kept informed.
- Ensure that all trial results do eventually become publicly available (through publication) and are subsequently used in systematic reviews of the evidence.
- Ensure that more ethical and worthwhile trials are undertaken by better defining the unanswered questions (through systematic reviews of completed trials) and through knowledge of similar trials in progress.
Many clinical trials, especially those with negative or inconclusive results, may fail to be published in medical journals. This risks the unethical use of healthcare resources and participants in trials. To prevent this, ethics committees should promote prospective registration of clinical trials and thus ensure that trial results can subsequently become publicly available.
- Antes G, Chalmers I. Under-reporting of clinical trials is unethical. The Lancet, 2004; 361(9362): 978.
- Dickersin K. Why register clinical trials? Revisited. Controlled Clinical Trials 1992; 13(5): 170-7.
- Dickersin K, Rennie D. Registering clinical trials. JAMA 2003; 290: 516-23.
- Horton R, Smith R. Time to register randomised trials. The Lancet 1999; 354: 1138-9.
- Simes RJ. Publication bias: the case for an international registry of clinical trials. Journal of Clinical Oncology 1986; 4: 1529-41.