1. PROSPERO
International prospective register of systematic reviews

2. Background: the need for registration
Systematic reviews usually provide the evidence base upon which health and social care decisions are made so they should be robust and free from bias
There is concern about publication and selective outcome reporting biases associated with systematic reviews
Unplanned duplication of reviews is a waste of resource
No open register for review protocols (Cochrane and Campbell Collaboration protocol registration limited to their own organisations)
PRISMA 2009 Checklist: asks for protocol and registration details
References:
Moher D, Tetzlaff J, Tricco AC, Sampson M, Altman DG. Epidemiology and reporting characteristics of systematic reviews. PLoS Med 2007; 4: e78.
PLoS Medicine Editors. Many reviews are systematic but some are more transparent and completely reported than others. PLoS Med 2007; 4: e147.
Silagy CA, Middleton P, Hopewell S. Publishing protocols of systematic reviews: comparing what was done to what was planned. JAMA 2002; 287: 2831–34.
Kirkham JJ, Altman DG, Williamson PR. Bias due to changes in specified outcomes during the systematic review process. PLoS ONE 2010; 5: e9810
Kirkham JJ, Dwan KM, Altman DG, et al. The impact of outcome reporting bias in randomised controlled trials on a cohort of systematic reviews. BMJ 2010; 340:c365.
Liberati A, Altman DG, Tetzlaff J, Mulrow C, Gøtzsche PC, Ioannidis JPA, Clarke M, Devereaux PJ, Kleijnen J, Moher D: The PRISMA statement for reporting systematic reviews and meta-analyses of studies that evaluate health care interventions: explanation and elaboration. PLoS Med 2009, 6(7):e
Moher D, Tetzlaff J, Altman DG, The PRISMA Group Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. In: PLoS Med. vol. 6; 2009: e

3. Taking the initiative
Following publication of the PRISMA statement CRD began to receive unsolicited requests to register systematic reviews
CRD has an established IT platform and infrastructure for the DARE, NHS EED and HTA databases
Set up an international advisory group
Carried out an international consultation to establish a minimum dataset and raise awareness
Membership of the advisory group:
Alison Booth, Centre for Reviews and Dissemination, University of York, York, UK
Lesley Stewart, Centre for Reviews and Dissemination, University of York, York, UK
Mike Clarke, Centre for Public Health, Queen’s University Belfast, Belfast, UK (formerly Director of UK Cochrane Centre)
Gordon Dooley, Metaxis, Oxford, UK
Davina Ghersi, Research Translation Branch, National Health & Medical Research Council, Canberra, Australia (formerly Coordinator of the WHO ICTRP)
David Moher, Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Canada; Department of Epidemiology and Community Medicine, faculty of Medicine, University of Ottawa, Ottawa, Canada
Mark Petticrew, Department of Social and Environmental Health Research, London School of Hygiene and Tropical Medicine, London, UK
Details of the Delphi consultation exercise have been published:
Booth A, Clarke M, Ghersi D, Moher D, Petticrew M, et al. (2011) Establishing a Minimum Dataset for Prospective Registration of Systematic Reviews: An International Consultation. PLoS ONE 6(11): e doi: /journal.pone
Booth A, Clarke M, Dooley G, Ghersi D, Moher D, Petticrew M, Stewart L. The nuts and bolts of PROSPERO: an international prospective register of systematic reviews. (submitted to Systematic Reivews; for publication early 2012)

4. Registration minimum dataset 22 required fields:
Review design
Administrative
Review question/objective
Condition/domain studied
Search details
Participants/population
Intervention/exposure
Comparator/control
Study types
Primary outcomes
Secondary outcomes
Risk of bias (quality) assessment
Strategy for data synthesis
Planned subgroup analyses
Review title
Named contact(s)
Contact
Organisational affiliation
Funding source/sponsors
Conflict of interests
Anticipated or actual start date
Stage of review†
Anticipated completion date
Review status†
† these fields are updated as the review progresses
Result of the consultation = minimum dataset 22 required fields – minimum to achieve aims of the register – registration form developed to make registration as straight forward as possible – level of information required is sufficient to allow others to see what was planned and allow comparison with what is reported on completion.
These are the fields that have to be completed before a form can be submitted.

5. Registration dataset 18 optional fields:
Administrative
Review design
Contact postal address
Contact phone number
Review team members & affiliations
Collaborators
Other registration details
Organisational reference number
Language
Country
Key words
Existing review by same authors
Any other information ‡
Type of review
URL to search strategy
URL to full protocol‡
Context
Data extraction methods
Dissemination plan
Link to final report/publication ‡ (added over time)
‡ Fields included in response to Delphi comments

6. PROSPERO: International prospective register of systematic reviews
Web based
Free to register
Free to search
Users create and update their own records
Minimum data set required
Record content is the responsibility of review lead
Administrators check for “sense” not peer review
A public audit trail of amendments is maintained
PROSPERO was launched on 22 Feb 2011

7. Eligibility for inclusion in PROSPERO
Systematic reviews of the effects of interventions and strategies to prevent, diagnose, treat, and monitor health conditions, for which there is a health related outcome
Exclusions: Reviews of reviews, Scoping reviews, Reviews of methods, Reviews of animal studies
Completed reviews are not accepted
Registration should take place once the systematic review protocol is finalised, but ideally before screening studies for inclusion begins
Working on automatic upload of Cochrane protocols, so they should not be registered individually
The long term aim is to have broad inclusion criteria for PROSPERO, such that any systematic review that has a health related outcome will be eligible. However, to achieve this aim, a stepped approach is being taken. To begin with the focus for inclusion is on …
Scoping reviews and reviews of reviews are not being included initially, but this decision will be re-considered in the future.
The inclusion of Cochrane review protocols is desirable to ensure a comprehensive overview of ongoing systematic reviews. To minimise additional work for Cochrane reviewers an electronic mechanism for their automatic upload from the Cochrane Library is being developed.
Timing: As registration requires the completion of a minimum dataset, registration can only take place after key issues have been considered, preferably through preparation of a protocol. For the register to achieve its aim of providing transparency and helping identify potential bias, registration should ideally take place before formal screening against inclusion criteria has begun, this being an early point at which bias could be introduced. However, the systematic review process is iterative by nature and some experimentation with searching is likely to be essential in developing the review. It also has to be recognised that researchers are often aware of some of the potentially eligible studies, and have an opinion on whether they are likely to include or exclude these, before they start formal screening.
Registering a review too soon might lead to multiple amendments to records as the protocol and the plans for the review are finalised; register later and the aim of publishing methods a priori could be missed. A practical approach to the timing of registration has been taken, initially. Registrants are asked to indicate the stage of progress of the review at the time of initial registration, and at any subsequent revisions, by ticking the boxes for the relevant stage from a list, with the option of adding further information in a free text box. All records and revisions are automatically dated when published to the register.
In recognition of reviews already underway during PROSPERO’s first year, systematic reviews at any stage before the point of completing data extraction are being considered for inclusion. The issue of timing of registration is to be reviewed as part of a planned evaluation of the register.

8. The story so far… PROSPERO opened for registration 22 February 2011
By November 2011:
Registered reviews being undertaken in 27 different countries
227 registrations published :
217 are ongoing reviews
8 are completed but not yet published
2 are completed and published
55 submissions rejected – almost all because they were too far advanced or completed on first submission

9. Current and future developments
Support from organisations such as Cochrane and Campbell Collaborations, Joanna Briggs Institute, G-I-N, INAHTA
Support from PLoS journals, BMJ and the new BMC journal Systematic Reviews
Establishing mechanisms with commissioning and funding organisations to facilitate grant holder uptake and compliance
National Institute for Health Research (UK)
Canadian Institutes of Health Research
Currently promoting registration phase of development and planning promotion of search facility
Evaluation after one year of operation planned

10. Visitors to the PROSPERO website
Between the launch on 22 Feb 2011 and 22 Nov 2011 the PROSPERO site had over 10,000 visitors from 104 different identifiable countries or territories