Box 115 Prospective registers of clinical trials

Prospective registration of a clinical trial means putting on public record some basic data at the time a trial starts. The aim is to provide the public, health providers, researchers and funding bodies with reliable information about research in progress.

Once completed, trial information remains in the register database.

♦ Registers are an invaluable source of information for those conducting systematic reviews or meta-analyses as they provide a valuable method of identifying unpublished and ongoing trials. Because trials are registered at the outset, this avoids the problems of publication bias.

♦ Registers provide a straightforward way for clinicians and researchers to learn about trials in their area of interest, to find out what new treatments are being investigated and potentially to decide whether they want to collaborate in such trials as participants.

♦ Anyone planning a new trial can find out whether anything similar has already been done or is currently ongoing. Such planning can help avoid unnecessary duplication of effort, or alternatively help aid trial design where confirmatory trials are required, as researchers can learn valuable lessons from previous studies.

♦ Funding bodies can make use of information from registers when assessing applications for future trials. They can check whether similar trials exist and can then take an informed decision about whether the planned new trial will contribute useful information.

♦ Registering trials may actually save effort for those running trials; if the information contained in the register provides sufficient information to answer routine queries, for example whether the trial is open or closed and how it is recruiting.

♦ Registering trials has the potential to improve recruitment as it can increase the level of awareness about the trial, both within the medical profession and in the patient population.

♦ Registration provides a means of assigning unique identifying numbers to trials (see Box 11.1).

The US government led the way with the FDA modernization act (1997) which required the establishment of a prospective database of all trials of new treatments for serious or life-threatening diseases (www.clinicaltrials.gov). In the UK, the Medical Research Council requires investigators to register their trials within their own directory of trials before it releases funds. Information from this directory is available through the metaregister of trials and its cancer trials via the UKCCCR register (Table 11.5). A further advantage of trial registration is that it provides a mechanism for assigning unique identifying numbers to RCTs. The international initiative to assign ISRCTNs - International Standard Randomized Controlled Trial Number - (see Box 11.1) to all new trials as they are registered, and to include this number in all publications, reports and presentation about the trial, will make it easy for reviewers to tell at a glance where multiple publications refer to the same trial (see Section 11.4.3). Openness about trials in progress reduces the impact of publication bias, prevents duplication of effort, promotes collaboration and can ultimately save lives [45]. Trial registration is therefore of value to all those involved in trials and research and to the general public. A list of web addresses for both cancer-specific and more general trial registers is given in Table 11.5.

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