Background. The question of how to determine when a systematic review needs to be updated is
of considerable importance. Changes in the evidence can have significant implications for
clinical practice guidelines and for clinical and consumer decision-making that depend on up-todate
systematic reviews as their foundation. Methods have been developed for assessing signals
of the need for updating, but these methods have been applied only in studies designed to
demonstrate and refine the methods , and not as an operational component of a program for
systematic reviews.
Results and Conclusions. Between June 2011 and June 2012, we established a surveillance
process and completed the evaluation of 14 CERs. Of the 14 CERs, 2 were classified as high
priority, 3 as medium priority, and 9 as low priority. Of the 6 CERs released prior to 2010
(meaning over 18 months before the start of the program) 2 were judged high priority, 2 were
judged medium priority, and 2 were judged low priority for updating. We have shown it is both
useful and feasible to do such surveillance, in real time, across a program that produces a large
number of systematic reviews on diverse topics.