8. Search
Present the full search strategies for all databases, registers, and websites, including any filters and limits used
Essential elements
Provide the full line by line search strategy as run in each database with a sophisticated interface (such as Ovid), or the sequence of terms that were used to search simpler interfaces, such as search engines or websites.
Describe any limits applied to the search strategy (such as date or language) and justify these by linking back to the review’s eligibility criteria.
If published approaches such as search filters designed to retrieve specific types of records (for example, filter for randomised trials)1 or search strategies from other systematic reviews, were used, cite them. If published approaches were adapted—for example, if existing search filters were amended—note the changes made.
If natural language processing or text frequency analysis tools were used to identify or refine keywords, synonyms, or subject indexing terms to use in the search strategy,23 specify the tool(s) used.
If a tool was used to automatically translate search strings for one database to another,4 specify the tool used.
If the search strategy was validated—for example, by evaluating whether it could identify a set of clearly eligible studies—report the validation process used and specify which studies were included in the validation set.5
If the search strategy was peer reviewed, report the peer review process used and specify any tool used, such as the Peer Review of Electronic Search Strategies (PRESS) checklist.6
If the search strategy structure adopted was not based on a PICO-style approach, describe the final conceptual structure and any explorations that were undertaken to achieve it (for example, use of a multi-faceted approach that uses a series of searches, with different combinations of concepts, to capture a complex research question, or use of a variety of different search approaches to compensate for when a specific concept is difficult to define).5
Explanation
Reporting the full details of all search strategies (such as the full, line by line search strategy as run in each database) should enhance the transparency of the systematic review, improve replicability, and enable a review to be more easily updated.57 Presenting only one search strategy from among several hinders readers’ ability to assess how comprehensive the searchers were and does not provide them with the opportunity to detect any errors. Furthermore, making only one search strategy available limits replication or updating of the searches in the other databases, as the search strategies would need to be reconstructed through adaptation of the one(s) made available. As well as reporting the search strategies, a description of the search strategy development process can help readers judge how far the strategy is likely to have identified all studies relevant to the review’s inclusion criteria. The description of the search strategy development process might include details of the approaches used to identify keywords, synonyms, or subject indexing terms used in the search strategies, or any processes used to validate or peer review the search strategies. Empirical evidence suggests that peer review of search strategies is associated with improvements to search strategies, leading to retrieval of additional relevant records.8 Further guidance and examples of reporting search strategies can be found in PRISMA-Search.9
Example
Note: the following is an abridged version of an example presented in full in supplementary table S1 on bmj.com.
“MEDLINE(R) In-Process & Other Non-Indexed Citations and Ovid MEDLINE were searched via OvidSP. The database coverage was 1946 to present and the databases were searched on 29 August 2013.
Urinary Bladder, Overactive/
((overactiv$ or over-activ$ or hyperactiv$ or hyper-activ$ or unstable or instability or incontinen$) adj3 bladder$).ti,ab.
(OAB or OABS or IOAB or IOABS).ti,ab.
(urge syndrome$ or urge frequenc$).ti,ab.
((overactiv$ or over-activ$ or hyperactiv$ or hyper-activ$ or unstable or instability) adj3 detrusor$).ti,ab.
Urination Disorders/
exp Urinary Incontinence/
Urinary Bladder Diseases/
(urge$ adj3 incontinen$).ti,ab.
(urin$ adj3 (incontinen$ or leak$ or urgen$ or frequen$)).ti,ab.
(urin$ adj3 (disorder$ or dysfunct$)).ti,ab.
(detrusor$ adj3 (hyperreflexia$ or hyper-reflexia$ or hypertoni$ or hyper-toni$)).ti,ab.
(void$ adj3 (disorder$ or dysfunct$)).ti,ab.
(micturition$ adj3 (disorder$ or dysfunct$)).ti,ab.
exp Enuresis/
Nocturia/
(nocturia or nycturia or enuresis).ti,ab.
or/1-17
(mirabegron or betmiga$ or myrbetriq$ or betanis$ or YM-178 or YM178 or 223673-61-8 or “223673618” or MVR3JL3B2V).ti,ab,rn.
exp Electric Stimulation Therapy/
Electric Stimulation/
((sacral or S3) adj3 (stimulat$ or modulat$)).ti,ab.
(neuromodulat$ or neuro-modulat$ or neural modulat$ or electromodulat$ or electro-modulat$ or neurostimulat$ or neuro-stimulat$ or neural stimulat$ or electrostimulat$ or electro-stimulat$).ti,ab.
(InterStim or SNS).ti,ab.
((electric$ or nerve$1) adj3 (stimulat$ or modulat$)).ti,ab.
(electric$ therap$ or electrotherap$ or electro-therap$).ti,ab.
TENS.ti,ab.
exp Electrodes/
electrode$1.ti,ab.
((implant$ or insert$) adj3 pulse generator$).ti,ab.
((implant$ or insert$) adj3 (neuroprosthe$ or neuro-prosthe$ or neural prosthe$)).ti,ab.
PTNS.ti,ab.
(SANS or Stoller Afferent or urosurg$).ti,ab.
(evaluat$ adj3 peripheral nerve$).ti,ab.
exp Botulinum Toxins/
(botulinum$ or botox$ or onabotulinumtoxin$ or 1309378-01-5 or “1309378015”).ti,ab,rn.
or/19-36
18 and 37
randomized controlled trial.pt.
controlled clinical trial.pt.
random$.ti,ab.
placebo.ti,ab.
drug therapy.fs.
trial.ti,ab.
groups.ab.
or/39-45
38 and 46
animals/ not humans/
47 not 48
limit 49 to english language
Search strategy development process: Five known relevant studies were used to identify records within databases. Candidate search terms were identified by looking at words in the titles, abstracts and subject indexing of those records. A draft search strategy was developed using those terms and additional search terms were identified from the results of that strategy. Search terms were also identified and checked using the PubMed PubReMiner word frequency analysis tool. The MEDLINE strategy makes use of the Cochrane RCT filter reported in the Cochrane Handbook v5.2. As per the eligibility criteria the strategy was limited to English language studies. The search strategy was validated by testing whether it could identify the five known relevant studies and also three further studies included in two systematic reviews identified as part of the strategy development process. All eight studies were identified by the search strategies in MEDLINE and Embase. The strategy was developed by an information specialist and the final strategies were peer reviewed by an experienced information specialist within our team. Peer review involved proofreading the syntax and spelling and overall structure, but did not make use of the PRESS checklist.”10
Training
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