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Library Research Guides

THL Evidence-Based Practice

Guides, Tutorials and Presentations offered by Taubman Health Sciences Library on Evidence-Based Practice

Citation Management

If you only have a few references for your project, manually adding them is likely to work well.

As your projects become more advanced, it may be worthwhile to learn how to use a citation management tool to store, organize, and format your references.

The THL Citation Management Guide provides tutorials on how to use several tools, including:

On This Page

Resources for Foreground Questions  

Provides links to resources for searching for evidence to answer foreground questions.

Create a Search Strategy from a Foreground Question  

Describes the step-by-step process of creating a search. 

Levels of Evidence  

Describes evidence by study types and their hierarchical relationship to each other.

MGetIt

Describes how to access and download articles from databases.

Citation Management

Lists available tools to organize your research, create citations, and format reference lists in numerous styles. Provides links to guidance about the tools via the THL Citation Management guide page.

Resources for Foreground Questions

Once you have developed a foreground question in the 1. ASK a Question step of the 5As EBP Process, you will need to select evidence-based resources to 2. Acquire the Information. When answering specific foreground questions related to patient care or a population group, it is important to check what the research says in evidence-based resources, such as clinical practice guidelines and scholarly articles.

An instructor, clinical preceptor, or attending physician may ask you to find evidence in specific types of resources.

U-M Library provides access to many literature databases that you can search for clinical practice guidelines, systematic reviews, or research articles that answer your foreground questions. In the health sciences, great starting points are:

When you are searching literature databases, use the MGetIt buttons to access the downloadable article PDFs. The title, abstract, and methods can help you determine whether an article is likely to contain evidence relevant to your foreground question.

Create a Search Strategy from a Foreground Question

Developing a search strategy based on a foreground question proceeds through the following recommended steps:

  1. Identify unique concepts
  2. Brainstorm related words
  3. Combine words using Boolean Operators
  4. Use phrase searching
  5. Apply filters to results 

Additional advanced searching techniques may be useful, depending on the topic and the database, and can be explored with an informationist.

We will use the foreground question in the 1. ASK a Question step of the 5As EBP Process as the building blocks of our search strategy.

To develop the search strategy from this foreground question, we will identify the unique concepts in the question. If you have applied a question framework, such as PICO, the elements in the framework are a great place to start.

In pediatric patients with asthma, does RSV infection compared to no infection impact admission to the ICU?

P (Patient, population, or problem): pediatric patients with asthma
I (Intervention, exposure, or test): RSV infection
C (Comparison): no infection
O (Outcome): admission to the ICU

 

The unique concepts in this search are pediatric, asthma, RSV infection, and ICU admission. 

For each unique concept it is often helpful to brainstorm synonyms or related terms.  This step is helpful for finding literature that is relevant to our question but using slightly different language than we originally thought of. We can organize our synonyms and related terms in tables. 

Pediatric

 Asthma RSV infection ICU Admission
pediatrics  difficulty breathing RSV intensive care unit
infant wheezing respiratory syncytial virus critical care unit
infants airway hypersensitivity    
child      
children      

 

For this type of information search It's not necessary to find all synonyms for each term, but investing time in developing a few can improve the search results. Here we demonstrate the idea behind considering various versions of our population concept words. While "infection" and  "admission" were identified as part of the RSV and ICU-portions of each concept respectively, we might try focusing on the RSV and ICU parts first. Searching requires testing out different approaches. In this instance, we should be prepared to adjust our terms and iterate. 

The next step is to use Boolean logic to combine our search terms and concepts.

First we will combine the synonyms and related terms using OR. Next we place parentheses around each concept group. Then we will combine all four concept with AND. This will allow us to find articles at the intersection of the four concepts. 

(pediatric OR pediatrics OR child OR children OR infant OR infants)

AND

(asthma OR difficulty breathing OR wheezing OR airway hypersensitivity)

AND 

(RSV OR respiratory syncytial virus)

AND

(ICU OR intensive care unit OR critical care unit)

 

 

 

Searching common phrases like intensive care unit as a phrase using double quotation marks may improve the relevance of the results. For each common phrase in the search strategy we are developing, we have added double quotation marks around the phrase.

(pediatric OR pediatrics OR child OR children OR infant OR infants)

AND

(asthma OR "difficulty breathing" OR wheezing OR "airway hypersensitivity")

AND 

(RSV OR "respiratory syncytial virus")

AND

(ICU OR "intensive care unit" OR "critical care unit")

For this search on RSV infection in a pediatric population, we will search for literature in the database PubMed and apply filters that are available in that database. 

PubMed provides several article type filters that can be applied to your search results. These filters are located on the left side of the results page after you have executed a search. Not all of the available filters appear by default. Click on "Additional filters" to see and select filters, click "Show" to show them on the results page. From the results page, click the desired filter(s) to apply them. The "Levels of Evidence" box below provides an overview of the Evidence Pyramid and definitions of various study designs to consider in your filter selection. Here we show a portion of the results page in PubMed for our search on RSV infection. The article type filters "Randomized Controlled Trial" and "Systematic Review"  are selected. With these filters applied, PubMed will return results matching our search terms that are either randomized controlled trials or systematic reviews. 

Search results in PubMed showing the article type filters "Randomized Controlled Trial" and "Systematic Review" selected

 

Note: Filters vary by database. For help selecting an appropriate database for your topic and for using its features and tools, contact us at thlibrary@umich.edu.

 

Levels of Evidence

Pyramid-shaped models are often used to display the relative levels of evidence of research study designs. Several names are used for these models, including:

  • Levels of evidence pyramid
  • EBP pyramid
  • Study design hierarchy

A research design's placement on an EBP pyramid provides information about its level of evidence. Meta analyses and systematic reviews are often listed at the top of EBP pyramids to indicate they are considered the highest levels of evidence. On the example EBP pyramid shown below, the primary study designs are randomized controlled trials, cohort studies, case control studies, and case series / case reports. Brief definitions of these study designs are available on the Study Designs tab of this box (above).

Level of Evidence Pyramid with two types of secondary literature at the top of the pyramid (that is, systematic review and meta analysis) and four primary literature study designs at the bottom of the pyramid. From top to bottom, the primary literature study designs are randomized controlled trial, cohort study, case control study, and case series or case report. A line separates the primary and secondary literature.

This level of evidence pyramid may be shared with you in sessions taught by informationists or librarians at the University of Michigan. Your textbooks or course materials may include other EBP pyramids or study design hierarchies. Other models may include additional study designs or information to help select high quality evidence to answer your clinical question.

Here are some additional examples:

Primary vs. Secondary Literature

  • Primary (unappraised) literature: Includes original individual studies, such as controlled trials, cohort studies, and case studies.
  • Secondary (pre-appraised) literature: Analyzes and interprets groups of primary studies, including systematic reviews and meta-analyses.
     
Pyramid shaped model of the levels of evidence for research study designs.

 

Secondary Literature Study Designs

  • Systematic Review:  Brings together and distills the best evidence from the primary literature to answer a clinical question. Generally, this will pool the results of several RCTs or meta-analyses on the same clinical problem. 
  • Meta-analysis:  A quantitative statistical analysis of several separate but similar experiments or studies in order to test the pooled data for statistical significance.

Key Primary Study Designs

  • Randomized Controlled Study:  A carefully planned experiment that studies the effect of therapy on real patients. Randomized controlled trials (RCTs) include methodologies (randomization and blinding) that reduce bias and that allow for comparison between an intervention group and a control group (no intervention). RCTs can provide sound evidence for cause and effect.
  • Cohort Study:  Follows patients who have a particular condition or receive a particular treatment over time, and compares them with another group who have not been affected by the condition or treatment being studied. Not as reliable as an RCT since the two groups might differ in ways other than the variable being studied. 
  • Case-Control Study:  A study in which people who already have a condition are compared with those who do not. The researcher looks back over time to identify factors that might be associated with the condition. Often relies on medical data or patient recall and is less reliable than an RCT or cohort study because cause and effect is not necessarily established.
  • Case Report:  A report on the treatment of an individual patient. Because there is no control group for comparison, there is no statistical validity. A number of case reports is a Case Series.

Caveat

Level of evidence hierarchies assume the studies were conducted according to the best practices for the particular study design. If a study's methodology does not follow best practices, the level of evidence for that study will be lower. This means a well-conducted, rigorous cohort study could provide better quality evidence than a poorly conducted randomized controlled trial. This is one reason Appraise is an important step in the Evidence-Based Practice process.

 

MGetIt

The video below demonstrates how to use the MGetIt link to access articles through the University of Michigan Library.