Authors' objectives:

" To estimate the average time to changes in evidence sufficiently important to warrant updating systematic reviews (referred to as the survival time) and to identify any characteristics that increase or decrease these survival times. : To determine the performance characteristics of various surveillance protocols to identify important new evidence. : To assess the utility of rates and patterns of growth for evidence within clinical areas as predictors of updating needs. : To establish typical timeframes for the production and publication of systematic reviews in order to assess the extent to which they impact survival time (e.g., whether or not delays in the peer review and publication processes substantially shorten the time in the public domain before new evidence requires updating of a given systematic review). : To characterize current updating practices and policies of agencies that sponsor systematic reviews."(Structured abstract)

Authors' recommendations: In a cohort of high quality systematic reviews directly relevant to clinical practice, signals for updating occurred frequently and within relatively short timelines. A number of features significantly affected survival, but none significantly predicted the need for updating within 2 years. Currently, definitive methods about the frequency of updating cannot be made. Blanket recommendation such as every two years will miss a substantial number of important signals for updating that occur within shorter time lines, but more frequent updates will expend substantial resources. Methods for identifying reviews in need of updating based on surveillance for new evidence hold more promise than relying on features of the original review to identify reviews likely to need updating within a short time, but such approaches will require further investigation. Several of the methods tested were feasible, yielding good recall of relevant new evidence with modest screening burdens. The majority of organizations engaged in the funding or production of systematic reviews view the importance of updating systematic reviews as high to very high. Despite this recognition, most organizations report having no formal policy in place for updating previous systematic reviews. Slightly less than half of organizations performed periodic literature searches to identify new evidence, but searching frequencies varied widely, from monthly to every two years. If systematic reviews are to achieve their stated goal of providing the best evidence to inform clinical decision making and healthcare policy, issues related to identifying reviews in need of updating will require much greater attention. In the meantime, publishers of systematic reviews should consider a policy of requiring authors to update searches performed over 12 months prior to submission. And, users of systematic reviews need to recognize that important new evidence can appear within short timelines. When considering the results of a particular systematic review, users should search for more recent reviews or trials to see if any exist and determine if the results are consistent with the previous review.

Authors' methods: Systematic review

Project Status: Completed

URL for project: http://www.ahrq.gov/clinic/tp/sysrevtp.htm#Report

Year Published: 2007

English language abstract: An English language summary is available

Publication Type: Not Assigned

Country: United States

Organisation Name: Agency for Healthcare Research and Quality

Contact Address: Center for Outcomes and Evidence Technology Assessment Program, 540 Gaither Road, Rockville, MD 20850, USA. Tel: +1 301 427 1610; Fax: +1 301 427 1639;

Contact Name: martin.erlichman@ahrq.hhs.gov

Contact Email: martin.erlichman@ahrq.hhs.gov

Copyright: Agency for Healthcare Research and Quality (AHRQ)