Why prospective registration of systematic reviews makes sense

In this launch issue of Systematic Reviews, we publish a series of linked articles about prospective registration of systematic reviews. This is a topic which has received increasing attention in recent years, notably in the 2009 PRISMA guidelines for preferred reporting items for systematic reviews and meta-analyses [1], and the subsequent development [2] and implementation [3] of PROSPERO, an international prospective register of systematic reviews which is described in this issue [4].We have devoted a substantial part of the first issue of Systematic Reviews to this topic because we believe that prospective registration of systematic reviews can play an important part in helping ensure the integrity of the evidence base upon which health policy and treatment decisions are made. A single point of access to information about ongoing reviews should also help avoid the unintended duplication of reviews and wasting of resources, a consideration that is more important than ever in the current economic climate.Given that systematic reviews are widely promoted as providing best evidence to inform decision-making, we believe that there is an associated responsibility to promote and encourage best methods and practice to ensure that systematic reviews are as transparent, robust and free from bias as possible.A key feature of a high-quality systematic review is the development of a protocol that sets out the main objectives, key design features and planned analyses for the review [5-7]. A protocol written in advance of the review should ensure that the review methods are transparent and reproducible, and adherence to this prespecified research plan should help avoid bias.Although protocol development is integral to systematic reviews carried out or funded by many organizations, authors of only about half of all reviews report having worked on the basis of a protocol [8]. Until the development of PROSPERO, there was no place to register protocol information that is open to a