Kaveh G. Shojania, MD; Margaret Sampson, MLIS; Mohammed T. Ansari, MBBS, MMedSc, MPhil; Jun Ji, MD, MHA; Steve Doucette, MSc; David Moher, PhD
Shojania KG, Sampson M, Ansari MT, Ji J, Doucette S, Moher D. How Quickly Do Systematic Reviews Go Out of Date? A Survival Analysis. Ann Intern Med. 2007;147:224-233. doi: 10.7326/0003-4819-147-4-200708210-00179
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Published: Ann Intern Med. 2007;147(4):224-233.
Clinicians rely on systematic reviews for current, evidence-based information.
This survival analysis of 100 meta-analyses indexed in ACP Journal Club from 1995 to 2005 found that new evidence that substantively changed conclusions about the effectiveness or harms of therapies arose frequently and within relatively short time periods. The median survival time without substantive new evidence for the meta-analyses was 5.5 years. Significant new evidence was already available for 7% of the reviews at the time of publication and became available for 23% within 2 years.
Clinically important evidence that alters conclusions about the effectiveness and harms of treatments can accumulate rapidly.
Includes the search protocols to identify candidate new trials, application of criteria from the original review to identify eligible new trials, meta-analytic pooling of new results with previous meta-analytic results, and identification of new systematic reviews on the same topic or “pivotal trials” (published in 1 of the 5 highest-impact general medical journals or more than 3 times the sample size of the previous largest trial) that met any of our criteria for qualitative signals for updating. An individual reviewer reached a tentative conclusion about the presence of quantitative and qualitative signals for updating, but each review was discussed in detail by the project team to reach a final consensus decision. For reviews that did not have any signals for updating, the group also decided whether the searches had been adequate or whether more comprehensive searching for new trials might be required, including more detailed electronic searching and hand-searching of for new trials relevant to the original review.
The immediate decrease in survival at time zero reflects the 7 systematic reviews for which signals for updating had already occurred at the time of publication. The low number of reviews at risk after 10 years reflects the fact that the sample spanned 1995 to 2005 and censoring occurred on 1 September 2006. Thus, only reviews published before September 1996 and having no signals for updating could have more than 10 years of observation.
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