Research Guides: Systematic Reviews & Other Syntheses: Searching for Studies

MEDLINE: Did you know?

You can search MEDLINE using PubMed or the Ovid interface. PubMed is a free resource that you will always be able to access, whereas Ovid MEDLINE is a proprietary resource that has been purchased by Queen's University Library. The Ovid interface and may be more user-friendly for new searchers than PubMed and provides a consistent look and feel if searchers will be accessing other databases on the Ovid platform such as Embase, Cochrane CENTRAL, PsycINFO, Global Health, and AMED.

Cochrane: Did you know?

The library provides access to two different interfaces for searching Cochrane Library: Wiley or Ovid. If your review will only be synthesizing primary studies, there is no need to search all of Cochrane Library (which also includes the Database of Systematic Reviews), instead, limit your search to Cochrane CENTRAL to retrieve trials only.

Introduction

Deciding where to search for studies will largely depend on the review question and type. A comprehensive search approach is often the goal, as many syntheses attempt to identify all evidence for a given research question.

Locating studies for syntheses often includes searching for both published and unpublished ("grey") literature.

The module to the right describes comprehensive searching for syntheses in detail.

Library Databases

Bibliographic/citation databases contain bibliographic information (e.g., citation information and abstracts but generally not full-text articles) for sources of literature. Queen's University Library (QUL) provides access to broad coverage databases in the health sciences (such as Ovid MEDLINE and Embase) as well as smaller subject-specific databases (such as PsycINFO and CINAHL).

The databases compared below are some of the most popular health sciences that QUL provides access to. These databases predominantly include bibliographic records of peer-reviewed journal articles, but in some cases also contain records for conference abstracts/papers, preprints, dissertations, and more.

Depending on your review topic, it may be appropriate to search databases from other disciplines. To discover more databases that might be relevant for your topic, browse or search the library databases, or speak with a librarian.

AMED - Allied and Complementary Medicine

Date Coverage: 1985 -
BIOSIS Previews

BIOSIS Previews combines the content of both Biological Abstracts and Biological Abstracts/RRM (Reports, Reviews, Meetings), thus providing comprehensive coverage of nearly 5,500 life science journals as well as 1,500 items from international meetings, review articles, books, book chapters, patents, and software reviews.

Subject coverage: All areas of life science, including such topics as: agriculture, biochemistry, biotechnology, ecology, immunology, microbiology, molecular genetics, neuroscience, pharmacology, public health, toxicology, zoology.

Because Queen's University Library subscribes to both BIOSIS Previews and Web of ScienceÂ®, a link in a full record from BIOSIS will take you to the corresponding record in ISI Web of Science.

Further information: Available on the vendor's website.
CINAHL and Pre-CINAHL

In addition, this database offers access to health care books, nursing dissertations, selected conference proceedings, standards of practice, educational software, audiovisuals and book chapters. Searchable cited references for more than 1,300 journals are also included.

Bracken Library Database Highlight: CINAHL:

https://youtu.be/UAnQfrw0Acg?si=wr3IH5GMyEV0R8_m

Date Coverage: 1981 - very recent articles
EBM Reviews - Cochrane Central Register of Controlled Trials
Cochrane Library
EMBASE

Date Coverage: 1947 - present
Global Health

The Global Health database covers the following aspects of human health and disease:

communicable diseases (including HIV/AIDS)
tropical diseases, i.e, diseases in the tropics (including field and experimental studies)
parasitic diseases and parasitology - medical entomology
human nutrition (including food composition, food poisoning, effects of diet on health, nutritional disorders, and experimental aspects)
community and public health (including chronic diseases, occupational health, health status indicators, the impact of agriculture on health, and cancer epidemiology)
medicinal and poisonous plants (including pharmacology, tissue culture, animal studies, plant composition, allergens, and toxins)

Date coverage: 1910 - present
MEDLINE

Date Coverage: 1946 to Present
APA PsycInfo [via Ovid]

REF BF1.P94 1927-1995 (Psychological Abstracts)

Date Coverage: 1806-present
PubMed

Bracken Library Database Highlight

Date Coverage: 1946 – present
Scopus

Date Coverage: 1788-present (updated daily)
Web of Science (Core Collection)

This database consists of these subject components, which can be searched simultaneously or individually (to search individually, limit to required citation database(s) at bottom of screen):

Science Citation Index Expanded - science and technology journals from 1900-present
Social Sciences Citation Index - social sciences journals from 1956-present
Arts & Humanities Citation Index - arts and humanities journals from 1975-present
Conference Proceedings Citation Index - Science (CPCI-S) from 1990-present
Conference Proceedings Citation Index - Social Science & Humanities (CPCI-SSH) from 1990-present
Journal Citation Reports (listing impact factors and other journal performance metrics) are available through Web of Science.

Science Citation Index: 1900 - present ; Social Sciences Citation Index: 1956 - present ; Arts and Humanities: 1975 - present

Database Comparison

	PubMed/ Ovid MEDLINE	Embase	CINAHL	PsycINFO	Cochrane CENTRAL	Web of Science
Years	1946- present	1947-present	1980- present	1806- present	1991-present	1900- present
Journals	>6,500	> 8,500	>3,100	>2,500	N/A	>33,000
Records	> 38 million	> 45 million	~8 million	> 5 million	> 500,000	>92 million
Record Types	Mainly journal articles	Journal articles, conference, preprints	Journal and magazine articles, dissertations, books	Journal articles, book chapters, dissertations	Trials (from databases, trial registries, etc.)	Journal articles, book chapters, conference
Subject Headings	MeSH	Emtree	CINAHL Subject Terms	APA Thesaurus Terms	MeSH, but only for records from MEDLINE	N/A
QUL Platforms	Ovid and PubMed	Ovid	Ebsco	Ovid and APA PsycNET	Ovid and Wiley	Web of Science
Notes	The Ovid platform is recommended for synthesis searching.

Supplemental Search Methods

In addition to database searching, supplemental search methods are recommended to help identify additional eligible studies [1-3].

Hand Searching - Conference Proceedings

Databases may not index conference proceedings, and even if they do, coverage may be limited. Hand-searching relevant conference proceedings that are available on association or conference websites may identify additional relevant studies.

Checking Reference Lists (Looking Back in Time)

Checking the reference lists of included studies allows you to examine if any additional eligible studies were cited by the included studies.

Checking Citing References (Looking Forward)

Checking the citing references (or "cited by" references) of included studies allows you to examine if any additional eligible studies cite the included studies.

For example, if you search for a relevant study in Google Scholar you will see a "Cited by..." link underneath the study information that indicates how many times the study has been cited (unless the study has not yet been cited). You can follow this link to view where the study has been cited to see if this locates any additional studies.

Reporting Standards

PRISMA Search is an extension to the PRISMA statement for reporting literature searches in systematic reviews [4]. The PRISMA-S checklist includes 16 reporting items, each of which is detailed with exemplar reporting and rationale:.

SECTION/TOPIC	ITEM	CHECKLIST ITEM
INFORMATION SOURCES AND METHODS
Database name	1	Name each individual database searched, stating the platform for each.
Multi-database searching	2	If databases were searched simultaneously on a single platform, state the name of the platform, listing all of the databases searched.
Study registries	3	List any study registries searched.
Online resources and browsing	4	Describe any online or print source purposefully searched or browsed (e.g., tables of contents, print conference proceedings, web sites), and how this was done.
Citation searching	5	Indicate whether cited references or citing references were examined, and describe any methods used for locating cited/citing references (e.g., browsing reference lists, using a citation index, setting up email alerts for references citing included studies).
Contacts	6	Indicate whether additional studies or data were sought by contacting authors, experts, manufacturers, or others.
Other methods	7	Describe any additional information sources or search methods used.
SEARCH STRATEGIES
Full search strategies	8	Include the search strategies for each database and information source, copied and pasted exactly as run.
Limits and restrictions	9	Specify that no limits were used, or describe any limits or restrictions applied to a search (e.g., date or time period, language, study design) and provide justification for their use.
Search filters	10	Indicate whether published search filters were used (as originally designed or modified), and if so, cite the filter(s) used.
Prior work	11	Indicate when search strategies from other literature reviews were adapted or reused for a substantive part or all of the search, citing the previous review(s).
Updates	12	Report the methods used to update the search(es) (e.g., rerunning searches, email alerts).
Dates of searches	13	For each search strategy, provide the date when the last search occurred.
PEER REVIEW
Peer review	14	Describe any search peer review process.
MANAGING RECORDS
Total records	15	Document the total number of records identified from each database and other information sources.
Deduplication	16	Describe the processes and any software used to deduplicate records from multiple database searches and other information sources.

Bibliography

Cooper C, Lovell R, Husk K, Booth A, Garside R. Supplementary search methods were more effective and offered better value than bibliographic database searching: a case study from public health and environmental enhancement. Res Synth Methods. 2018 Jun;9(2):195-223. doi: 10.1002/jrsm.1286.
Horsley T, Dingwall O, Sampson M. Checking reference lists to find additional studies for systematic reviews. Cochrane Database Syst Rev. 2011 Aug 10;2011(8):MR000026. doi: 10.1002/14651858.MR000026.pub2.
Lefebvre C, Glanville J, Briscoe S, Featherstone R. et al. Chapter 4: Searching for and selecting studies [last updated March 2025]. In: Higgins JPT, Thomas J, Chandler J, Cumpston M, Li T, Page MJ, Welch VA (editors). Cochrane Handbook for Systematic Reviews of Interventions version 6.5.1 Cochrane, 2025. Available from cochrane.org/handbook.
Rethlefsen M, Kirtley S, Waffenschmidt S, Ayala AP, Moher D, Page MJ & Koffel J. PRISMA-S: an extension to the PRISMA statement for reporting literature searches in systematic reviews. Syst Rev. 2021 Jan 26;10(1):39. doi: 10.1186/s13643-020-01542-z.

Training Module

An inter-professional team led by Queen's has set out to develop an open access module series titled The Essentials of Conducting Systematic Reviews to introduce researchers to all stages of the systematic review process.

Check out Module 3: Searching for Eligible Studies.