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Evidence Based Practice

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If you have seen this message when you are searching the library databases, it means that the database vendor may suspect you of setting a robot, spider, or Web wanderer to mine the database to conduct excessive downloading. Although each vendor or publisher has their own definition of what constitutes excessive, is it usually defined as downloading a large number of articles in a short period of time.

How Can You Help?

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We know that you will often need to download large numbers of results for your research into Mendeley. As long as you are sure that these are the results you need and that you cannot change your keywords to further refine your search, please download the CITATIONS only. For example, use the "save citations" option from the database, or uncheck the PDF option in the Mendeley Web Importer...

saving citations from Sage

saving citations using Mendeley Web Importer


Once you have screened these article citations for relevance, you can then download the corresponding PDF files into Mendeley.

SEARCH for evidence

Melnyk & Fineout-Overholt (2015, p. 10), Step 2 = "Search for and collect the most relevant best evidence".

Search Tips


It is not often that you will be able to find a single paper that addresses your research question fully. You might need to review your search and look at different papers that each deal with part of your question, and then synthesize that information.


  1. Check your Spelling
    Most search engines cannot interpret typo errors or spelling mistakes

  2. Use Simple Search Terms
    More search terms will yield fewer results. For e.g., a search for osteoarthritis AND women AND (older OR elderly) (19,408 results) will get you far fewer results than using only osteoarthritis (97,506 results)

  3. Use Quotation marks around phrases

    "continuous passive motion" tells the search engine to find all of those words in a row, exactly as you typed them, rather than looking for those words separately in the document

  4. Use the generic name of drugs when possible

    PubMed and many database index drugs by their US generic names. However, when trying to verify information about a specific formulation of a drug, search by trade name and be careful to spell it correctly

  5. Use AND to combine search terms
    Most search engines interpret osteoarthritis AND women or osteoarthritis  women  as being the same, i.e. BOTH words will appear in your results

  6. Use Search Limits to get more relevant articles
    Limiting your results to year of publication, source type or languages can help reduce the number of irrelevant citations


Weinfield, J.M., & Finkelstein, K. (2005). How to answer your clinical questions
more efficiently. Family Practice Management,12(7). 37-41.

Medical Subject Headings (MeSH) are part of a controlled vocabulary designed specifically to index biomedical information in such a way that it can be more easily found. It was created and is kept updated by the US National Library of Medicine (NLM). 

 Library databases that work well with MeSH:

  1. CINAHL 
  2. PubMed

Search for MeSH terms here

search medical subject headings



Boolean operators

Boolean operators are commonly used in databases to connect your search words together to either narrow or broaden your set of results. The three basic boolean operators are: AND, OR, and NOT.

To NARROW a search and include both terms - paramedics AND epinephrine

To BROADEN a search and include any or all terms - children OR adolescent

To ELIMINATE unrelated terms - rock NOT music

Phrase Searching " " - search the words together in a sentence, not as separate keywords

cardiac arrest, rock climbing

Truncation *

educat* finds educate, educates, education, educating

Wildcard ?

psych????y finds psychiatry, psychology (but not psychotherapy)

Different databases use different truncation symbols so it is important to check the database 'Help' information or 'Search Tips' for details about which symbol to use.

Search Strategy Builder

Designed to help you build a simple search string or statement using 2 Boolean operators; cut and paste the resulting search statement into the search box of a library database.


Enter your keywords here Key concept 1  AND  Key concept 2  AND  Key concept 3
search terms
search terms
search terms
Enter alternate search terms for each concept. Use single words, or "short phrases" in quotes.














Adapted from original creation by University of Arizona Libraries and licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License

 Jensen, K.A. (n.d.). 7 steps to the perfect PICO search: Evidence-based Nursing practice. EBSCO Health | CINAHL Complete.

The highest or strongest levels of evidence appear near the top of the Evidence Pyramid, and can be harder to find (if such evidence exists at all). 

Evidence Pyramid - Levels of Evidence

Not sure where on the evidence pyramid to place an article you have found? Not sure what type of study design is being used? This article may help you decide...

 Ingham-Broomfield, R. (2016). A nurses' guide to the hierarchy of research designs and evidence. Australian Journal of Advanced Nursing, 33(3), 38-43. /archive/Vol33/Issue3/5Broomfield.pdf

 Systematic Review

A systematic overview of all the peer reviewed evidence (studies) surrounding a particular research question (topic). Very useful for finding answers to focused research questions but the reviews may not be as objective as they appear so try to find the original studies for use in your own research. A systematic review may or may not include a Meta Analysis, which is a quantitative summary of the results.

play button What are systematic reviews? by Cochrane Consumers & Communication Group (3:23 mins)

SAMPLE ARTICLES : [ Systematic Review | Meta Analysis ]

green bullet Critically Appraised Topic (CAT)

Not nearly as detailed or meticulous as a systematic review, a critically appraised topic provides a very brief summary of the best research evidence organized around a clinical question. 

bullet pale blue  Randomized Controlled Trial (RCT)

An experimental comparison study in which the trial participants are randomly assigned to the treatment/intervention or control/placebo groups. Best for studying the effect of an intervention but can be ethically problematic in cases where interventions are withheld.

bullet mid blue  Cohort Study

A study that compares two identical groups of subjects, where only one of the groups has been exposed to a certain risk factor. Used to investigate the causes of disease and establish links between risk factors and outcomes. Can be retrospective or prospective.

SAMPLE ARTICLE : [ Cohort Study ]

bullet blue  Case Control Study

A retrospective study that begins with a disease or outcome of interest, and traces back to investigate the exposures. The cases are the group known to have the disease, the controls are the group known to be free of the disease.
SAMPLE ARTICLE : [ Case Control Study ]

bullet blue  Cross Sectional Study

An observational study where subject selection is based on the inclusion and exclusion criteria set for the study. Outcomes and exposures in the subjects are measured at the same time.
SAMPLE ARTICLE : [ Cross Sectional Study ]

bullet blue  Case Series & Case Reports

Studies on the treatment of a single patient, or a series of individual patients. Very detailed information is provided, but there are no control groups, so there is very little statistical validity.

SAMPLE ARTICLE : [ Case Series ]

bullet lilac  Background information and Expert Opinion

No studies involved, expert opinion consists of recommendations from those with established experience in their fields. Like background information, expert opinion can be very helpful, but may also be biased in terms of beliefs, opinions, religion, politics, etc.

Definitions adapted from:

Primary Sources

Primary sources in the field of medical and health sciences are typically journal articles detailing original research. They are important because they are often the original sources of new knowledge. An example of a primary sources is a quantitative or qualitative research study that describes an intervention and its outcome on a specific population.

What kinds of studies are considered as Primary Sources?
  • Clinical Trials
  • Randomized Control Trials
  • Multicentre Studies
  • Epidemiology Studies
  • Prospective Studies
  • Retrospective Studies
  • Cohort Studies
  • Case Control Studies
  • Cross-sectional studies
  • Case reports / Case series

Professional organizations are a great place to start looking for current events, issues facing practitioners, and conflicts within the health law arena.

A formal written statement detailing the particular action to be taken in a particular situation that is contractually binding.

The essence of the legislation was to empower the public with the right to make life or healthcare decisions. It is important for you to understand the related regulations so as to make binding, legally enforceable decisions for yourself and for your patients.

Source : NHS Wales Informatics Service. (2006). Using protocols, standards, policies and guidelines to enhance confidence and career development. Crown Copyright.

Secondary Sources

Secondary sources are summaries and analyses of the evidence derived from and based on primary sources. They provide an appraisal of the quality of studies and often make recommendations for practice.

What kinds of studies are considered as Secondary sources?
  • Clinical Practice Guidelines
  • Meta-Analyses
  • Systematic Reviews
  • Critically-Appraised Topics
  • Critically-Appraised Individual Articles

Clinical Practice Guidelines (CPGs) practice recommendations based on the best available evidence; written by healthcare organizations. Guidelines are meant as recommendations for patient care based on the available evidence.



Systematic reviews focus on peer-reviewed publications about a specific problem. Rigorous, standardized methods for selecting and assessing articles are used to limit bias in the assembly, critical appraisal, and synthesis of all relevant studies on a specific topic.

A systematic review may or may not include a meta-analysis, which is a quantitative summary of the results.

A Critically Appraised Topic (CAT) is a short summary of the best available evidence, created to answer a specific clinical question. it is liked a concise and less rigorous version of a systematic review.

Some examples of CAT:-

Critically Appraisal articles refer to a structured abstract and expert commentary for a particular topic. In certain databases, they are also also known as Review Articles. 

An agreed framework outlining the care that will be provided to patients in a designated area of practice. They do not describe how a procedure is performed, but why, where, when and by whom the care is given.
SAMPLE ARTICLE : [ Protocol ]

A statement, reached through consensus, which clearly identifies the desired outcome. Usually used within audit as a measure of success.
SAMPLE ARTICLE : [ Standards of Medical Care in Diabetes ]

Guideline *
Systematically derived statements that help practitioners to make decisions about care in specific clinical circumstances. These should be research or evidence based.
SAMPLE ARTICLE : [ Jaundice in newborn babies under 28 days ]

Note : * Similar resources

Source : NHS Wales Informatics Service. (2006). Using protocols, standards, policies and guidelines to enhance confidence and career development. Crown Copyright.