The changes are part of a review of the requirements promised by the International Committee of Medical Journal Editors (ICMJE) when the organisation first set them down in 2005.

The initial policy required clinical trial investigators to deposit information about trial design into an accepted clinical trials registry before the onset of patient enrolment. At the time, five registries met the ICMJE criteria.

Now the organisation has said it will also accept registration of clinical trials in any of the primary registries that participate in the World Health Organization's (WHO) International Clinical Trial Registry Platform (ICTRP).

"Fortunately, the WHO's ICTRP, which was nascent when the ICMJE began to require trial registration, has matured rapidly and provides options for those that desire a wider array of registries", said the ICMJE in an editorial published on Tuesday.

"The ICTRP has taken the first steps toward developing a network of primary and partner registers that meet WHO-specified criteria."

Primary registers are WHO-selected registers managed by not-for-profit entities that will accept registrations for any interventional trials, delete duplicate entries from their own register, and provide data directly to the WHO. Partner registers, which will be more numerous, will include registers that submit data to primary registers but limit their own register to trials in a restricted area (such as a specific disease, company, academic institution, or geographic region). Under the ICMJE's evaluation, however, registration in a partner registry only, is insufficient.

"Because it is critical that trial registries are independent of for-profit interests, the ICMJE policy requires registration in a WHO primary register rather than solely in a partner register, since for-profit entities manage some partner registers," said the editorial authors.

As was the case previously, trial registration with missing or uninformative fields for the minimum data elements remains inadequate. In addition, the ICMJE said it "will not consider results posted in the same clinical trials registry in which the primary registration resides to be previous publication if the results are presented in the form of a brief, structured (<500 words) abstract or table".

Furthermore, Phase I trials (preliminary trials designed to study pharmacokinetics or major unknown toxicity) were previously exempt from the regulations, however, the ICMJE is now expanding the definition of the types of trials that must be registered to include these preliminary trials and said it has adopted the WHO's definition of a clinical trial to mean "any research study that prospectively assigns human participants or groups of humans to one or more health-related interventions to evaluate the effects on health outcomes".

"The ICMJE member journals will start to implement the expanded definition of clinically directive trials for all trials that begin enrollment on or after 1 July 2008. Those who are uncertain whether their trial meets the expanded ICMJE definition should err on the side of registration if they wish to seek publication in an ICMJE journal", the authors stated.

The organisation said it did so because "it recognises the potential benefit of having information about preliminary trials in the public domain, because these studies can guide future research or signal safety concerns".

In the past there has been fierce debate over the inclusion of Phase I studies in the registries, with the resistance primarily due to their highly sensitive commercial nature, and therefore many in the industry, especially drug companies will not be pleased with the news.

One industry body, the International Federation of Pharmaceutical Manufacturers & Associations (IFPMA), has been quoted in the past as saying that requiring registration of early exploratory trials could "slow development or even prevent innovation in certain cases, without providing ... benefit to doctors and patients".

At the time, Roche echoed these sentiments, saying that it operates its own register but excludes early Phase I studies "to avoid confusing healthcare providers and creating false expectations for patients suffering from serious diseases".

However, the extent to the new requirement for Phase I trials will really inpact the industry may only be minimal.

Roche, has also previously commented that most medicines tested in these first human studies never progress to marketed compounds and these exploratory clinical trials generally do not generate data which are later used to support clinical claims or recommendations for use, while only relevant findings are published in peer reviewed journals.

Details of the updated policy appear in the editorial on the ICMJE website, (www.icmje.org ), along with the websites of the 12 'officially' participating journals.

The original clinical trials policy was collectively established after it became apparent that there was a great need to ensure that information about the existence and design of clinically directive trials was publicly available.

Indeed, the initiative also sought to soothe the growing public demands for transparency regarding all clinical trials after a spate of recent high-profile drug recalls, culminating in the dramatic withdrawal in 2004 of prescription painkiller Vioxx, after an independent retrospective study of the drug raised alarming cardiovascular safety concerns.

Vioxx had been available on the market for five years and was being used to treat millions of patients before these safety concerns finally led to its swift withdrawal. There have since been several allegations made by whistleblowers that the drug company covered up unfavourable clinical trial results, and that the practice may be rampant throughout the industry.

Although resisted at the time by many research investigators and sponsors, who feared that registration would be burdensome and would stifle competition, it has since been "embraced," said the ICMJE, who added that before the policy, ClinicalTrials.gov, the largest trial registry at the time, contained 13 153 trials; but this number climbed to 22 714 one month after the policy went into effect and in April 2007, the registry contained over 40 000 trials, with more than 200 new trial registrations occurring weekly.

"The four other registries that meet the ICMJE criteria have also grown as scores of journals have adopted the ICMJE clinical trials registration policy," the organisation said.

In response to this burgeoning registration, many investigators, sponsors, and government agencies asked the ICMJE to recognise their local registries as databases that meet the policy.