The sky’s the limit: PROSPERO hits the 10,000 registered systematic reviews milestone

Launched in 2011, PROSPERO was the first registry dedicated to systematic review registration. Today, marks the registration of the 10,000th review, and Lesley Stewart, Director of the Centre for Reviews and Dissemination at University of York, which launched the register, discusses this landmark achievement.

Today PROSPERO, the international prospective register of systematic reviews reached a major milestone when the 10,000th review was registered.

Launched in February 2011 by the Centre for Reviews and Dissemination (CRD) at the University of York with the support of an international advisory group, PROSPERO aims to increase transparency, avoid unintended duplication and reduce opportunities for bias during systematic review conduct and reporting. It also provides a rich source of information about the design and conduct of systematic reviews that can be used for research purposes.

Registration records are maintained permanently, irrespective of whether the review is subsequently published and include audit trails of any design changes made after registration.

Readers can use the PROSPERO registration number to link between published articles and corresponding registration records, and compare whether what is reported in the published review matches what was planned in the registered protocol. Commissioners and researchers can check PROSPERO for any ongoing reviews already addressing their topic before embarking on new research.

A much-needed innovation

I am delighted by the rapid progress we have made in establishing registration as an increasingly routine aspect of systematic review conduct.

I am delighted by the rapid progress we have made in establishing registration as an increasingly routine aspect of systematic review conduct. To have increased the rate of new registration records from an average of 15 per week in 2011 to 115 a week in 2015, in less than five years this is a real achievement.

Rapid growth no doubt stems partly from the fact that PROSPERO, which is funded by the National Institute for Health Research (NIHR) in the United Kingdom, is online, offers public access and makes no registration or usage charges.

This reduces barriers to participation for researchers working in low and middle income countries, and I am particularly pleased that PROSPERO is a truly international endeavor. The 10,000 records include registrations from 92 countries.

Success has also been fostered by widespread organizational support. The NIHR has shown leadership in research transparency by making registration in PROSPERO a condition for release of funding, and other commissioners, such as the Canadian Institutes of Health Research, encourage registration.

Systematic Reviews, which publishes full systematic review protocols, asks specifically for a registration number as part of the protocol submissions process. Other BioMed Central, PLoS and BMJ Group journals also endorse registration of systematic reviews in their instructions to authors.

Growth has also been helped by the fact that registration of protocol details is straightforward and most researchers complete the online form in less than hour. Inexperienced reviewers have told us that they have found that the registration template (and the optional downloadable form) has helped them structure their review protocol and made them think in advance about important aspects of design.

Since October 2014, new protocols published in the Cochrane Library have been added to PROSPERO automatically enabling us to now provide a ‘one-stop shop’ for information about on-going systematic reviews. Cochrane reviews make up around 10% of the content of PROSPERO.

Future developments

So far, the majority of registered reviews are of health-related interventions, but this is evolving rapidly.

So far, the majority of registered reviews are of health-related interventions, but this is evolving rapidly.

When developing PROSPERO, we decided to focus initially on reviews of interventions, but with an eye to future expansion.

PROSPERO already includes diagnostic, prognostic and epidemiologic reviews, reviews of service delivery, and prevention and we have recently broadened the scope to include all systematic reviews relevant to health and social care, welfare, public health, education, crime, justice, and international development, with health-related outcomes.

We will shortly be launching a new interface that will improve searching large numbers of records and improve user experience. We are excited to be working with an international collaboration to include protocols of systematic reviews of pre-clinical studies.

It’s been enormously rewarding to be involved with the development of PROSPERO and to reach this important landmark. Here’s to the next 10,000 registrations.

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