Updating

Scope: methods for updating and explorations of issues around updating searches; comparisons of different methods of updating

Appraisal of: "Sampson M. Complementary approaches to searching MEDLINE may be sufficient for updating existing systematic reviews. J Clin Epidemiol 2016; 78: 108-115."

Short description: 

The aim of the article was to test whether the combined approach of a focused Boolean search paired with a second search using the similar articles feature of PubMed or support vector machine (SVM) can yield high recall with reasonable precision.

The general approach of a Boolean plus a ranking search is effective in MEDLINE retrieval for systematic reviews. Very high levels of identification of relevant MEDLINE records, with adequate precision, are possible using a focused Boolean search complemented by a document similarity or ranking method.

Limitations stated by the author(s): 

There are two limitations to our proposed strategy. Other databases should be searched in the unusual event that numerous studies, representing more than a small proportion of the total N, are not included in MEDLINE. Second, when it is important to find articles too new to be indexed by MEDLINE, systematic reviewers may wish to conduct a simple PubMed search limited to the nonindexed subsets.

Limitations stated by the reviewer(s): 
It is not possible to reproduce or use the support vector machine functionality.
Study Type: 
Single study

Appraisal of: Sampson M, Shojania KG, McGowan J, Daniel R, Rader T, Iansavichene AE et al. Surveillance search techniques identified the need to update systematic reviews. J Clin Epidemiol 2008; 61(8): 755-762.

Short description: 

The article reports on literature surveillance methods to identify new evidence eligible for updating systematic reviews. Five surveillance search approaches are tested in the context of identifying studies that would signal major or invalidating new evidence for existing systematic reviews of health care interventions.

Searches were tested in a cohort of 77 systematic reviews. No one method yielded consistently high recall of relevant new evidence, so combinations of the strategies were examined. A search algorithm based on PubMed’s related article search in combination with a subject searching using clinical queries was the most effective combination, retrieving all relevant new records in 68 cases. Citing RCT searching found unique material in only 2 cases (recall 37%).

Surveillance for emerging evidence that signals the need to update systematic reviews is feasible using a combination of subject searching and searching based on the PubMed’s related article function.

Limitations stated by the author(s): 

The retrospective observational design used here has certain limitations including absence of control over data collectiondin the case of the CENTRAL database, where indexing dates of records are not recorded; this limited our ability to determine when new evidence would have been available to reviewers. Our assessment of the point at which a review was in need of update could have been influenced by our access to subsequent confirmatory evidence, although any resulting bias would influence each search approach equally.

Limitations stated by the reviewer(s): 
No additional limitations were detected by the authors.
Study Type: 
Single study

Appraisal of: Sampson M. Updating searches for systematic reviews [dissertation]. Department of Information Studies: University of Aberystwyth; 2009.

Short description: 

This thesis examines methods for updating searches for systematic reviews of healthcare interventions on the base of 77 systematic reviews. The Related Article search showed the highest recall. Relative performance of the test searches was consistent regardless of whether the intervention was a drug, device or procedure. All searches showed variability across clinical areas, but Related Articles RCT showed the most consistency. The pairing of Related Article RCT and Clinical Query gave excellent recall of new relevant material.

Limitations stated by the author(s): 

Screening method, generalization of results on precision (cohort was only 10 AHRQ Evidence Reports), the selection of the sample may have implications for generalizability.

Limitations stated by the reviewer(s): 
No additional limitations were detected by the reviewers.
Study Type: 
Single study
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