Background: Maintaining currency of Cochrane reviews is challenging, and it is unclear how often a review should be updated. Identifying the frequency of changes that would directly inform clinical decision-making could be helpful to determine frequency of updating reviews. DynaMed is a clinical reference using a systematic methodology for identifying, selecting, critically appraising, summarizing, and synthesizing evidence and guidelines to provide concise and precise representations of the most valid and relevant information for clinical decision-making at the point of care. Management overviews withinDynaMed topics represent a systematic selection of current practice-driving evidence. DynaMed is updated daily.

Objectives: To measure the rate of change in management overview due to new evidence in 1 year.

Methods: Overviews from 200 DynaMed topics will be analyzed for changes over 1–2 years. Each change will be classified as resulting from new evidence or guidance, user feedback, or quality improvement.

Results: As of April 14, 2012 overviews of 33 topics have been evaluated for change over 0.84–1.78 years. Twenty-seven overviews (82%) changed based on new evidence and 26 (79%) changed based on new guidelines. Thirty-one overviews (94%) changed based on new evidence or new guidelines. Among 1808 lines in these overviews, 515 (28%) were modified and 225 (12%) were deleted; 365 new lines (20%) were added. Of the 1105 changes, 578 (52%) were due to new evidence or guidelines. The annualized rate of change of overview content due to new evidence or guidelines was 22.2%.

Conclusions: More than 20% of core information guiding clinical practice is changed within 1 year. Updated results will be presented along with an analysis of how many changes are from Cochrane reviews, and how many changes could inform Cochrane reviews.