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The NAU library website for the Phoenix Biomedical Campus Library

Overview of EBP

Definition of EBP

"Evidence-based medicine is the conscientious explicit and judicious use of current best evidence in making decisions about the care of individual patients." (Sackett 1996)

Optimal use of EBP involves carefully balancing: clinical expertise, the best evidence available, and patient values + circumstances.

Evidence-based practice diagram

As you read through the following tabs, consider each of these three components. Ask yourself:

  • How do I define my own expertise, and can that change, expand, or even become more narrow?
  • How do I decide what qualifies as the "best" evidence? And how do I find it?
  • How do I ensure that my patients are treated equitably and given agency to make their own informed decisions?

i also recommend working through this checklist for conducting evidence-based research, as it can be used anytime one is looking for evidence:

You might also want to branch out and read through a few papers and organizational sites that define (and in some cases, problematize) EBP:


Construct a concise clinical question.

The first step in EBP is to write a focused clinical question. That question will be translated into a database query in step two. Best practice is to define your research question and identify which types of studies or publications would be best suited to that question before searching the literature. You should also be aware of the patient, if you are seeing one, and how their needs are informing your research.

Once you've considered the foundational components of your research, the next step involves constructing a question relevant to your needs and your patient's needs. It should be framed using the PICO acronym:


What kind of person is the patient? What is their diagnosis? What is their particular situational need?


How would you describe the specific intervention you are considering?


Is their a control group? Is there are an alternative intervention? (Keep in mind: not all questions have a "comparison" component)


What is the desired outcome? Does it involve reduction, relief, or elimination of symptoms? Can it be measured with a test?

Time / Type:

What time periods should be considered?  What study types are most likely to have the information you seek?  What clinical domain does your question fall under?

For further help with PICO, work through the following examples:


It can be helpful to classify your question based on the clinical domain(s) it falls under.  

See below for definitions, PICO templates, and example questions from the primary clinical domains: interventiondiagnosisetiologypreventionprognosis/predictionquality of life/meaning, and therapy.


Questions addressing the treatment of an illness or disability.

In _________ (P), how does _________ (I) compared to _________(C) affect _______(O) within _______ (T)?
In _______(P), what is the effect of _______(I) on ______(O) compared with _______(C) within ________ (T)?

In African American female adolescents with hepatitis B (P), how does acetaminophen (I) compared to ibuprofen (C) affect liver function (O)? (Time is optional).



Questions addressing the act or process of identifying or determining the nature and cause of a disease or injury through evaluation.

Are (is) _________ (I) more accurate in diagnosing ________ (P) compared with ______ (C) for _______ (O)?
In ________ (P) are/is ________(I) compared with ________(C) more accurate in diagnosing ________(O)?

Is a PKU test (I) done on two week old infants (P) more accurate in diagnosis inborn errors in metabolism (O) compared with PKU tests done at 24 hours of age (C)? Time is implied in two weeks and 24 hours old.
In middle-aged men with suspected myocardial infarction (P), are serial 12-lead ECGs (I) compared with one initial 12-lead ECG (C) more accurate in diagnosing an acute myocardial infarction (O)?



Questions addressing the causes or origin of disease, the factors that produce or predispose toward a certain disease or disorder.

Are ____ (P) who have _______ (I) at ___ (Increased/decreased) risk for/of_______ (O) compared with ______ (P) with/without ______ (C) over _____ (T)?

Are ______(P) who have ______(I) compared with those without _______(C) at ________ risk for/of _______ (O) over ________(T)?

Are kids (P) who have obese adoptive parents (I) at Increased risk for obesity (O) compared with kids (P) without obese adoptive parents (C) during the ages of five and 18 (T)?
Are 30- to 50- year old women (P) who have high blood pressure (I) compared with those without high blood pressure (C)at increased risk for an acute myocardial infarction (O) during the first year after hysterectomy (T)?



Questions on how to reduce the chance of disease by identifying and modifying risk factors and how to diagnose disease early by screening.

For ________ (P) does the use of ______ (I) reduce the future risk of ________ (O) compared with _________ (C)?

In OR nurses doing a five minute scrub (P) what are the differences in the presence and types of microbes (O) found on natural polished nails and nail beds (I) and artificial nails (C) at the time of surgery (T)?



Questions addressing the prediction of the course of a disease.

Does __________ (I) influence ________ (O) in patients who have _______ (P) over ______ (T)?
In _______ (P), how does ________ (I) compared to ________ (C) influence _________ (O) over _________ (T)?

Does telelmonitoring blood pressure (I) in urban African Americans with hypertension (P) improve blood pressure control (O) within the six months of initiation of the medication (T)?
For patients 65 years and older (P), how does the use of an influenza vaccine (I) compared to not received the vaccine (C) influence the risk of developing pneumonia (O) during flu season (T)?


Quality of Life/Meaning

Questions addressing how one experiences a phenomenon.

How do ________ (P) diagnosed with _______ (I) perceive ______ (O) during _____ (T)?

How do pregnant women (P) newly diagnosed with diabetes (I) perceive reporting their blood sugar levels (O) to their healthcare providers during their pregnancy and six weeks postpartum (T)?
How do 20 something men (P) with a diagnosis



Questions around how to select treatments to offer our patients that do more good than harm and that are worth the efforts and costs of using them.

In _______(P), what is the effect of _______(I) on ______(O) compared with _______(C) within ________ (T)?

What is the duration of recovery (O) for patients with total hip replacement (P) who developed a post-operative infection (I) as opposed to those who did not (C) within the first six weeks of recovery (T)?

Further reading


Levels of Evidence Pyramid | Click Here

Question Type & Study Design

Some study designs are better suited to answer certain types of questions. Identifying the clinical domain your question falls under can help determine what study designs to look for in order to find the best, most suitable evidence. Systematic Reviews and Meta-Analyses are always preferred.

Check off the clinical domain and preferred study design type on the Well-Built, Patient-Oriented Clinical Question worksheet. The link to that worksheet can be found above.

Clinical Domain
Preferred Study Design (after systematic reviews and meta-analyses)
Cost-Effectiveness Economic Analysis
Diagnosis Cross-Sectional Studies or Gold Standard
Etiology or Prognosis Cohort > Case-Control > Case Series
Prevention Randomized Controlled Trial > Controlled Trial > Cohort > Case-Control
Quality of Life Qualitative Studies
Therapy Randomized Controlled Trial > Controlled Trial or Quasi-Experimental Studies

For example:

Clinical question: In adults with total hip replacements, how effective is pain medication compared to aerobic stretching in controlling post operative pain during the perioperative and recovery time?

Clinical domain: Therapy

Preferred study designs: Systematic Reviews/Meta-analysis | Randomized Controlled Trials | Conrolled Trials

Acquiring evidence

Foreground vs. Background information

Foreground information is the complex, precise information often needed in order to answer a PICO question.  Before searching for foreground information, however, make sure you have a good understanding of each of the PICO concepts.  If you don't have adequate knowledge about one of your PICO concepts, you will need to pursue background information in order to fully understand the foreground information you find. 

Resources for background information

Finding foreground information

Following from the levels of evidence pyramid described on the Ask tab, information resources can be collapsed into three broad categories: summaries and guidelines, pre-appraised research, and non-appraised primary studies. See below for descriptions and examples of each.

EBP resources
Summaries and guidelines

summarizes the evidence from a topical level, can be used as practice guidelines

Resource examples

Open access: Natural Medicine | Professional Organizations

Databases: BMJ Best Practices | DSM V TR | Rehabilitation Reference CenterUpToDate

Pre-appraised resources

Summaries of high-level evidence concerning a specific research topic

Resource examples

Open access: Annals of Internal Medicine | NARIC PLOS MedicinePubMed Health

Databases: CINAHL | Cochrane | OTSeeker | PubMed (MEDLINE, PMC, NCBI) | PEDro

Non-appraised primary studies    

Primary original research that has not been preappraised

Resource examples

Open access: Google Scholar | PubMed Central | PLOS Medicine | TRIP

Databases: CINAHL | OvidMD | PubMed (MEDLINE, PMC, NCBI)

A note about appraised resources

For practitioners who need immediate, credible information, appraised resources are highly preferred. BMJ Best Practices and UpToDate are two specific resources that can be leveraged at or around point-of-care. Keep in mind that PubMed also indexes appraised information; however, it is more difficult to parse due to PubMed's scope.

Appraised resources can be found across most scholarly journals, although it is important to remember: 1) editorials, opinions, and responses should not count as critically appraised sources 2) appraised resources exist on a spectrum from most heavily appraised (review-type papers) to randomized-controlled trials, non-randomized trials, and qualitative studies.

Click here to review NAU's complete journal listings.

Complete list of NAU health science databases

Conducting a search

After constructing your PICO(T) question and finding the resource that best suits your needs, it's time to build and conduct a search. Listed below are strategies and tools that will make it easier to find information that is most applicable to you and your patients.

As you think about your search keep in mind the following:

  • Typically, searches should seek high sensitivity, which will generate a more broad return. This may result in lower precision, but it becomes less likely that searchers will miss important information.
  • Avoid using too many search concepts; concepts are the primary terms that align with your search needs. At the same time, a variety of synonymous search terms should be combined in conjunction with each concept.
    • IE: Intervention (concept) = hip strengthening | "hip flexor" OR "hip extension" OR "hip exercise" OR "hip stretch" OR ""hip stretches" OR hip stretching" OR "foam roll" OR "foam roller" OR "foam rolling" (search terms)
  • Familiarize yourself with Boolean operators AND, OR & NOT, and apply them within your search string, both between concepts and between search terms -- use AND to separate concepts; use OR to separate search terms; use NOT to exclude unwanted concepts (ie: stroke NOT "heat stroke")

For help building these strategies into a search string, check out the University of Arizona search strategy builder.


When searching for information in PubMed / MEDLINE, it's generally recommended to include MeSH Terms in your search. These are the "Medical Subject Headings" used by the National Library of Medicine to locate relevant articles. 

For help with MeSH, see this short tutorial:

Additional search strategies

In order to further narrow and refine your search, remember to:

  • Use search filters to limit results, particularly when delineating between reviews, clinical trials, and/or other paper types
  • Look for information that is timely when assessing for current trends
  • Do not limit your search to Full Text, as you can request articles not owned by NAU through Document Delivery Services
  • Be prepared to look in more than one database, and never expect that one database is a one-stop shop for information

Creating a MyNCBI account


Evaluating your findings

Once you have collected your findings, they must be properly assessed for validity as well as applicability. 

To find out if a finding is valid, ask:

  • What was the study design, and is it appropriate for this clinical domain?
  • Did experimental and control groups begin the study with a similar prognosis?
  • Did experimental and control groups retain a similar prognosis after the study started?
  • What are the results? Specifically, how large and precise was the treatment effect?
  • How prevalent was bias? (NOTE: see below for more information regarding bias)
  • Are results clinically significant in addition to being statistically significant?

To find out if a finding is applicable, ask:

  • Were study patients similar to my patient?
  • Were all patient-important outcomes considered?
  • Are the likely benefits worth the potential harms and costs?
  • Does the intervention impose upon my patient's values and circumstances?
  • Does this resource help me answer a PICO(T) question well enough to analyze and write about it myself?
  • Does this study have wider significance to my field?
  • Can this study be improved upon by further study?

Assessing for bias

Particularly for those conducting reviews (literature, scoping, systematic, etc.), it is important to assess for risk of bias. The following bullets, attributed to the Cochrane Handbook for Systematic Reviews, can help you ascertain the prevalence of bias in a given study:

  • A bias is a systematic error, or deviation from the truth, in results or inferences. Biases can operate in either direction: different biases can lead to underestimation or overestimation of the true intervention effect. Biases can vary in magnitude: some are small (and trivial compared with the observed effect) and some are substantial (so that an apparent finding may be entirely due to bias). Even a particular source of bias may vary in direction: bias due to a particular design flaw (e.g. lack of allocation concealment) may lead to underestimation of an effect in one study but overestimation in another study. It is usually impossible to know to what extent biases have affected the results of a particular study, although there is good empirical evidence that particular flaws in the design, conduct and analysis of randomized clinical trials lead to bias.
  • Bias should not be confused with imprecision. Bias refers to systematic error, meaning that multiple replications of the same study would reach the wrong answer on average. Imprecision refers to random error, meaning that multiple replications of the same study will produce different effect estimates because of sampling variation even if they would give the right answer on average. The results of smaller studies are subject to greater sampling variation and hence are less precise. Imprecision is reflected in the confidence interval around the intervention effect estimate from each study and in the weight given to the results of each study in a meta-analysis. More precise results are given more weight.
  • A study may be performed to the highest possible standards yet still have an important risk of bias. For example, in many situations it is impractical or impossible to blind participants or study personnel to intervention group. It is inappropriately judgmental to describe all such studies as of ‘low quality’, but that does not mean they are free of bias resulting from knowledge of intervention status.
Types of bias
Selection bias

systematic differences between baseline characteristics of the groups that are compared

Performance bias

Systematic differences between groups in the care that is provided, or in exposure to factors other than the interventions of interest.

Detection bias                 

Systematic differences between groups in how outcomes are determined.

Attrition bias

Systematic differences between groups in withdrawals from a study.

Reporting bias

Systematic differences between reported and unreported findings.

Critical appraisal resources

Logo for the centre of evidence-based medicine The Centre for Evidence-Based Medicine (CEBM) stores worksheets to guide the appraisal process. 


EBP/EBM databases


eBooks from the collection


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