Search Manual (ARCHIVE)

Please refer to the latest Search Functionality Information available in the The Cochrane Library click here.

Overview of The Cochrane Library

The Cochrane Library is composed of a number of different databases including the Cochrane Database of Systematic Reviews (Cochrane Reviews) [which includes records previously published in the Cochrane Database of Methodology Reviews (Methods Reviews)], the Database of Abstracts of Reviews of Effects (Other Reviews), the Cochrane Central Register of Controlled Trials (Clinical Trials, or CENTRAL), the Cochrane Methodology Register (Methods Studies), the Health Technology Assessment Database (Technology Assessments), and the NHS Economic Evaluation Database (Economic Evaluations).

The contents of these databases can be found through a variety of search tools. All of the databases except CENTRAL can also be browsed through the "Browse Articles" selections that are displayed on all pages.

Browsing The Cochrane Library

The Browse feature allows you to access articles through an alphabetically sorted listing or table of contents for most of The Cochrane Library's databases. To access the browse lists, select a link under the "Browse" section for one of the The Cochrane Library's databases. The primary selection is Cochrane Reviews, which can be sorted by Topic, New Reviews, Updated Reviews, the A-Z alphabetical sort, and Review Group. Other selections include Other Reviews, Clinical Trials, Methods Studies, Technology Assessments, and Economic Evaluations. Choosing the browse link for the Other Resources displays an alphabetically sorted browse page for all selections except the Clinical Trials.

Note: Because the large number of records in the Clinical Trials database makes the use of a Browse feature impractical, records are instead selected through the Advanced Search. Users may enter a wildcard * character in the search box, select Clinical Trials only from the product restriction section, and run the search to retrieve all records in the Clinical Trials database.

You can access The Cochrane Library homepage directly from any other page by clicking on Home link near the top of the page.

The browse lists include the following special features:

Cochrane Reviews: These can be selected through Topic, New Reviews, Updated Reviews, the A-Z alphabetical sort, and Review Group lists. The A-Z alphabetical list of records allows you to also filter on Protocol and Review. Each Cochrane Review includes a free abstract section. The record listing includes a link to the document in HTML or PDF format, a file size, and an icon identifying the document as a Protocol or Review. Document status icons are included for specific documents and can include:

New: A new protocol or review that has been published in the most recent issue.
Update: A new search for studies has been conducted and any new studies found have been incorporated into the review in the most recent issue.
Conclusions changed: There has been an important change to the conclusions of the review published in the most recent issue.

Major change: The protocol has been amended to reflect a change in scope published in the most recent issue.

Withdrawn: The review or protocol has been withdrawn, which may be because it was considered to be out of date. Reasons for withdrawal are specified in the document.

Comment: The review includes comments. Readers can submit comments, which are incorporated into the review together with answers and feedback from the review authors.
Methodology: A full-text systematic review of methodological studies.
Other Reviews: Documents are displayed in an alphabetical listing.
Clinical Trials: No browse list is included for Clinical Trials due to the huge size of the index. The Clinical Trials browse link accesses the The Cochrane Library's Advanced Search, which allows you to limit the database selection to Clinical Trials and search for specific terms.
Methods Studies: Documents are displayed in an alphabetical listing.
Technology Assessments: Documents are displayed in an alphabetical listing.
Economic Reviews: This alphabetical list of records also allows you to also sort by documents that have been critically appraised and others that have only bibliographic data.

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Searching The Cochrane Library

Cochrane Library users have access to a number of different search methods for locating content within The Cochrane Library or for searching all of the titles included in the Wiley Online Library. The basic Search option is included in the upper right sections of The Cochrane Library homepage. The search and link options include:

Basic Search: The basic Search box at top right allows you to enter search terms in a single text box. The search box includes the option to select a field restrictor.

Cochrane Advanced Search: This option allows you to access the full search feature page for Cochrane.
MeSH Search: This option allows you to access a thesaurus-based search of medical search terms.
Search History: Searches that you have input during your current session can be accessed from this feature.
Saved Searches: This option allows you to display and manage previously saved searches and search strategies created with the Advanced Search and MeSH Search.

The Cochrane Library includes two enhanced searches.

The Cochrane Library Search, or Cochrane Advanced Search, includes specialized fields for restricting searches on the product's databases.
The MeSH Search (Medical Subject Headings) provides a thesaurus for searching on a multi-level hierarchy of more than 22,000 descriptor terms.

The Cochrane Library also includes two special search features for building complex queries and saving search strategies.

The Search History, feature allows you to build and save complex searches using current search terms and adding new terms through the page's search function.
The Saved Searches feature allows you to display and manage previously saved searches.

A navigation bar for selecting the four search options is displayed at the top of the search pages.

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The Cochrane Library Advanced Search

The Cochrane Library Advanced Search allows users to create more complex searches and provides a number of options for refining search results. Major features include:

  • Use the five search text boxes at the top of the screen to include search terms.
  • Search Tips in the right column of the search screen provide hints on standard search methods using wildcard truncation, inline Boolean operators, quotation marks to specify exact terms, and brackets to group terms.
  • Boolean selector pulldown boxes in front of the text boxes can be used to relate the terms using the AND, OR, or NOT operators.
  • The pulldown list boxes following the text box can be used to limit the search to the following fields:
    • All text
    • Record title
    • Author
    • Abstract
    • Keywords
    • Title, Abstract, or Keywords
    • Tables
    • Publication type
    • Source
    • DOI
  • Use the Restrict Search by Product section to limit the search to a specific Cochrane Library database or databases.
  • Use the Restrict Search by Record Status section to limit the records to one of the special record status types. The status of the record is displayed on the search results page.
  • Use the Date Range section to limit the search to a range of publication years. Enter the years in the full xxxx format.
  • Click the Search button to view the search results.
  • From the search results page, use "Edit Search" to modify your current search.
  • Use "Search History" to view and edit searches in your current session.

Tips for Using the Advanced Search Feature

In general, an assumed "AND" operator is used for spaces between terms. Thus, a search for acute bronchitis will match any document that includes both terms.
The following table provides a listing of specific querying options, methods, and guidelines for the Advanced Search.

Type Description Example
Boolean operators Use AND, OR, and NOT to create a more complex search. magnesium sulfate AND (eclampsia OR perinatal asphyxia)
Proximity search using NEAR Use NEAR/ with a number to indicate proximity of terms either before or after each other. The default proximity value for the operator when no number is entered is 6. antidepressant NEAR/10 narcolepsy
Proximity search using NEXT Use NEXT with a number to match terms that appear next to each other. Note that the apostrophe within a term is treated as a space, thus to search for adjacent words in a term such as Down's Syndrome, the best search parameter to use is:
down* NEAR/2 syndrome
cholera NEXT treat*
Combined Boolean and proximity searches Use combinations of Boolean operators and proximity operators to build a complex search. breast NEAR (cancer OR carcinoma)
Wildcard truncation Use an asterisk (*) to search for multiple characters before, within, or after a search string. A question mark can be used to search for a single character. abdom* *eclampsia
Comma instead of OR operator Use a comma in place of the OR operator medical, health
Exact phrase search Insert a term within quotation marks to create an exact match. Note that no search method is case sensitive, thus "PH" matches the same results as "pH", "Ph", or "ph". "mental health treatment" matches the phrase in exactly that word sequence
Stemming The stemming feature within the search allows words with small spelling variants to be matched. The term tumor will also match tumour. tumor cell
Pluralization and singularization matches Pluralized forms of words also match singular versions, and vice versa. The term drugs will find both drug and drugs. To match either just the singular or plural form of a terms, use an exact match search and include the word in quotation marks. "vaccine"
Terms with multiple spellings Use the wildcard character with the NEXT operator to match all variations of a term. Note: Use NEAR between a word ending in "'s" and another following word. st* NEXT john* NEAR wort
Diphthong characters Terms with spelling variations that include diphthongs should be searched with a wildcard character to ensure that all forms of a term are matched. Some more common terms with diphthongs such as "haemorrhage" are automatically matched to their variant spellings through stemming. isch*mic stroke
Stop words Words such as "in," "the" and "of" are matched in the search. The Boolean search operators AND, OR, NOT, NEAR, and NEXT are the only terms treated as stop words.
Accented characters For all fields except Author, accented characters are not matched by their equivalent unaccented form. To match accented characters use the following options: 1) Use the wildcard characters (* or ?) for a broad match, 2) if the term is displayed on a page you are viewing, copy and paste it to the search box, 3) select the term from a list of accented characters. If entering an accented term in the search box, also include the unaccented version with an OR operator to match all cases. Partial list of accent characters: ¤ Ì ‰ „ € ‡ ˆ ‹  Š Ê Œ ý Ž ÿ û ò º ü ù ¢ ÷ Ë Ÿ ¹
Hyphenated terms Hyphens are treated as a space with an associated NEXT operator. The term heart-related will match the same results as heart NEXT related. evidence-based NEXT medicine

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Search Results

To view the Search Results page, enter a search in one of the search features and select the Search button in the Advanced Search or the View Results button in the MeSH search.

The total number of record matches within each of The Cochrane Library database is displayed in the "Show Results" section near the top of the page. Click on the individual links to display the results for each database. The selected database link is displayed in black.

The input search parameter is displayed below the database selectors. Beneath the search term are links for each paged section of the search results. Any search that includes more than 25 results within a database will be displayed on multiple pages. Select the page section link or Next button to navigate between search results pages. Select the sorting links at top right to sort results alphabetically by title, the match percentage (relevancy) of the search, or by the year of publication.
The search results for each record include the document title, author, and year of publication data. Records for Cochrane Reviews display a Protocol or Review image to indicate whether the document is a protocol or review, and a Methodology image if it is a methodology review. Some document listings also include a status indicator such as "New" or "New search." To view a document, click on the title link.

Search terms are not highlighted within the selected record. To locate a term within the HTML version of a document, click on the text frame, Press Control-F to display the Find feature, type the search term in the Find search box, and select the "Find Next" button to locate the term. You can also select the PDF version of a document if available to use the enhanced Acrobat search feature.

Searches can be saved by selecting the "Save Search" button at the top right. Searches can be revised by selecting the "Edit Search" button.
Records can be exported to citation format by using the export options. The "Export All Results" button will select all records in the search for exporting, but you can also use the check boxes next to each record to select individual records or use the "Select All" option to select all records on a page. The citation export feature is discussed in a separate section.

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MeSH Search

The Medical Subject Heading (MeSH) Search is based on the National Library of Medicine's controlled vocabulary thesaurus of medical subject headings. MeSH includes both an alphabetical and hierarchical listing of related sets that allow you to browse lists for specific terms. The MeSH Search feature can be accessed by clicking on the MeSH Search link on the navigation bar on the Cochrane Advanced page or the MeSH Search link in the search box on The Cochrane Library homepage.
The MeSH index terms for each Cochrane Library document are listed in the Index section. Many terms include a MeSH subject qualifier that is displayed in brackets after the term. MeSH searches can be run directly from within the document by clicking on an index term.
The Cochrane Library's MeSH Search includes two forms for searching, by MeSH descriptor and by MeSH subject qualifier.

The MeSH terms are updated on The Cochrane Library annually (April), subsequently saved searches need to be updated with the new MeSH terms, to ensure accurate result.

Search by MeSH Descriptor

MeSH terms are indexed in a hierarchical tree structure format that links related terms, which can be further specified through the addition of a qualifier.
Terms can be searched for directly within the MeSH tree or you can use the Thesaurus feature to view a permuted index for the term. To view the index, type a term in the search box and click the "Thesaurus" option. The thesaurus index will also be displayed if the term you entered is not in the MeSH tree index. The thesaurus index displays a list of all MeSH terms that include the term you selected. Click on a listing to display the MeSH tree structure for the phrase. Note that only one term can be used for the Thesaurus feature and multi-word terms will be searched only on the first word entered. The scientific meaning for a term can also be displayed by entering a term in the search box and clicking the Definition option.

To view a MeSH tree structure, enter a MeSH term within the search box and click on the "Go To MeSH Trees" button. The tree structure for your selected term will be displayed in the lower "Search The Cochrane Library content" section. The left column displays a full listing of the matched trees for your selected term. The listing of MeSH terms for each tree is displayed in the right column, and each tree includes all the terms that are at a higher and lower level from the selected term. Listings that include subsidiary branches are followed by a number in brackets such as [+5], which shows the number of lower-level branches. These branches can be displayed by clicking on the term to explode the listings. Any term that is clicked on is displayed in the MeSH tree search box.

The default search option shown in the left column is Explode All, which will search on all the terms in the trees. You can refine your search by clicking on the check box in front of the tree listings to select specific trees. You can also select the "Search this term only" option to further narrow your search.

Two other options can be selected from section above the MeSH tree structure lists. You can select a qualifier restriction to limit the search to a specific subject field such as "agonists" or "toxicity." Multiple qualifiers can be selected, and you can enter the qualifier codes directly into the qualifier search box separated by commas. You can also select the "Go directly to Search History" to move to the Search History feature when you run the MeSH tree search.
To run a MeSH Tree search with your selected terms or hierarchical branches, select the "View Results" button.

MeSH terms in Cochrane:

Cochrane Reviews: Fully indexed, New reviews are indexed within 2 months of being published.
Cochrane Protocols: No MeSH indexing
CENTRAL Clinical Trials: Only records taken from Medline: Fully Indexed EMBASE and Handsearch: No MeSH indexing
Other Reviews: Fully indexed
Health Technology Assessments: Fully indexed
Economics Evaluations: Fully indexed

Searching on Qualifiers

MeSH Search subject qualifiers can be used separately from the MeSH Tree search. Select the "Search by qualifier alone" option beneath the Search navigation bar to display the Qualifier Search page. Select one or more selections from the drop-down menu or enter qualifier codes, such as "CY" for "Cytology," directly in the search box, separating each selection by a comma. Select the "Go" button to run the search.

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Search History

Searches run during your current session are saved in your Search History profile. The feature is accessed by clicking on the Search History option in the Search navigation bar or the link in the main search box. The Advanced Search and MeSH search also have options that you can select to go directly to the Search History page.

The Search History feature is a powerful tool that allows you to build complex combined searches through use of search IDs and search operators. At the top of the page is a condensed search form that can be used to add searches and build combined searches. The search form feature is discussed in the Building Combined Searches section below.

The queries listed in your current search history include an ID order number, the Search description, the total number of Hits the search matches, and Edit and Delete options.

Searches can be run by clicking on a search string.
Searches can be edited by clicking the "Edit" selection next to the search. The search will be displayed within the Search History search editor.
Searches can be deleted by clicking on the "Delete" selection next to the search. Searches that follow the deleted search and have higher ID numbers will have their ID number decremented by 1. Any combined search that includes a deleted search will automatically be revised to eliminate the deleted search value and recalculate the Hits result.

Below the Search History listing section are two buttons for saving search strategies and clearing the search history. Click "Save Search Strategy" to save the current search history listing. The popup form lets you enter a name for the search strategy and add comments. After saving the search, the Saved Searches page is displayed with the new search strategy included. You can click the "Search History" option on the search navigation bar to return to the Search History page. An option below the "Save Search Strategy" button lets you save a modified search history under a different name. The "Clear History" button removes all searches from your current Search History settings.

Note: when building complex search strategies, it is important to save your current search strategy at regular 10- to 15-minute intervals to ensure your searches are retained.

Searching with field labels is allowed for the Search History page (but not for the Advanced Search). You can enter the term antibiotics:ti to find the term in the Title field. Field label abbreviations include abstract (:ab), author (:au), keywords (:kw), source (:so), title (:ti), publication type (:pt), tables (tb), or DOI (:doi). Terms can be applied to multiple fields by separating the field codes by commas, as in oncology:ti,ab,kw

Building Complex Searches

The condensed search form at the top of the Search History page can be used for developing complex search schema. The search form has a single search box for entering text strings, product limit, a date-range restrictor, and a record status limiter. At the simplest level, the form can be used in a similar format as the Advanced Search to build a quick search query. But the form can also be used to combine search numbers to build complex searches. After entering the search terms, you select the "Go" button and the new search is added to the Search History list with next highest ID number.

Complex searches are built by using the searches ID numbers and associating them with search operators. The ID number is preceded by the # character in the search string. A simple example of a combined search is:

#3 OR #4 AND #8 which would be parsed as (#3 OR (#4 AND #8))

To build a complex query that correctly associates the hierarchy of search terms, use parentheses to group the elements.

(#3 OR #7 OR #19) AND (#17 AND #5) will match any documents that include query #3 or #7 or #19 if the result also includes #17 in combination with #5.

The NOT operator can be used to restrict searches:

#12 NOT #7 selects only terms found in search #12 that are not included in #7.

Text terms can be combined with search ID numbers to create a new search.
whooping cough AND #12

Be aware that deleting a search will affect other searches that included it as one of the search parameters.

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Saved Searches

The Saved Searches page provides a method for storing and maintaining individual searches and search strategies. The page is accessed by clicking on the "Saved Searches" option on the search navigation bar on search pages.

You can save individual searches by clicking the "Save Search" selection on a Search Results page or clicking on the "Save Search Strategy" selection on the Search History page. Individual searches are listed by their full query string and have a search profile alert feature. You can use the Start\Stop toggle to set an email alert to notify you when a new document is published in The Cochrane Library that matches the search. Search strategies are listed according to the name you selected for them in the Search History feature. They do not include the email alert feature.

Searches are run by clicking on the Run option on the saved search line. They can be exported to a text file by clicking on the Export button. Check boxes in front of each search can be used to select and delete a listing using the "Delete Checked Items" at the bottom of the page. The "Select All" button allows you to select all of the listings.

Users with existing "Saved Searches" or "Alerts" for reviews using specifically the flags "Updated", "Commented", or "Commented and Updated" will need to edit them and select the new flags described earlier.

Viewing a Document

Articles are viewed by selecting the title on a browse menu or by selecting a record in a search result. Except for the CENTRAL database records, the document display format includes a left-column table of contents section that allows quick navigation within the document. Documents include some or all of the following features:

Abstracts and plain language summaries.
Bibliographic links to online versions of references.
Links to PDF versions of Cochrane Reviews documents.
Links to MeSH Search terms.
Links within Cochrane Reviews documents to meta-analysis diagrams for studies included in the documents.
Links to supporting editorial groups.

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Citation Export

The Citation Export feature is accessed through links on the Search Results page or through the "Export Citation" link in the table of contents section of Cochrane Review combined set, DARE, CENTRAL, HTA, and NHS EED documents. The data for a large number of records can be exported by using options on the Search Results page. The data records are exported in Text formats and can be imported into standard reference manager programs. The data exported includes standard publication fields for document and publication title, author, year, source, volume number, and keywords.

To export citation records, first make a selection of records on the Search Results page or through the export option within the document. After you select the "Export Citation" option, a popup window will be displayed to let you choose your export options. Selections are available for selecting Citation-only or Citation and Abstract formats for the record along with selections for PC, Macintosh, or UNIX machine formats for the file. After you have made your selections and clicked the "Go" button, you can select to save the file or open it directly within your reference manager program.

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Statistical Analysis Diagrams

Many Cochrane Reviews include forest plots displaying the results of each included trial, and a pooled result if the included trials have been meta-analysed.

The forest plots can be accessed by clicking on the "Figures" tab within each Cochrane Review, and then by selecting each analysis. The full-size diagram for a particular analysis is displayed in a popup window.

Statistical data are also available to download by clicking on the "Article" tab within a Cochrane Review, navigating to "Data and analyses", and then clicking the link "Download statistical data". The data are available as a raw data file in XML.

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