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Nursing Research Guide: Evidence Based Research

This research guide features resources and strategies for finding information and conducting research related to Nursing.

What is evidence based research?

In 1996 Professor David Sackett and colleagues developed the first working definition of evidence-based medicine in their seminal article "Evidence Based Medicine What It Is and What It Isn't." Sackett et al. propose: "Evidence-based medicine is the conscientious, explicit, and judicious use of current best evidence in making decisions about the care of individual patients. The practice of evidence-based medicine means integrating individual clinical expertise with the best available external clinical evidence from systematic research" (p. 71). 

Evidence-based research can inform clinical practice. Evidence-based practice's greatest strength is its emphasis on helping healthcare professionals and patients make informed decisions about patient care and treatment options. As Hoffmann, Bennett, and Del Mar encourage, the evidence-based practice research process can be broken down into 5 steps: 

1. Convert your information needs into an answerable clinical question

  • This is often in the form of a PICO question: Patient (or Problem or Population or Person), Intervention (or diagnostic test or prognostic factor or issue), Comparison, Outcome(s). 
    • Example PICO Question: For patients undergoing procedures, how does providing patients with pre-procedural education and discharge instructions compared to patients who only receive education post-procedure impact patient anxiety and satisfaction?

2. Find the best evidence to answer your clinical question

3. Critically Appraise the evidence for its validity, impact, and applicability 

  • Validity: Are the evidence and methodology trustworthy? 
  • Impact: If the evidence and methodology are trustworthy, do you trust the study's results? What is the impact (i.e. clinical importance) of the evidence?
    • For example, if a new drug has a positive effect on patient outcomes, is there a large enough effect to change clinical practice? 
  • Applicability: If the research passes the validity and impact stages, consider whether these results apply to your specific patient, population, etc. As Hoffmann, Bennett, and Del Mar provide, "Essentially, you need to assess whether your patient is so different from the participants in the study that you cannot apply [the study's results] to your patient" (p. 10)

4. Integrate the evidence with clinical expertise; the patient's values, preferences and circumstances, and information from the clinical context

  • Can I clearly explain the research evidence to patients and involve them in making informed decisions about their care, where appropriate? 

5. Evaluate the effectiveness and efficiency with which steps 1-4 were carried out, and think about ways to improve your performance next time 

Source: Hoffman, T., Bennett, S., & Del Mar, C. (2013). Evidence-based practice across the health professions (3rd ed.). Elsevier.

Question Types and Best Resources

As you are developing your PICO question, you will need to find resources that best address your clinical query. Specific research designs are able to better answer certain types of research questions. For example, if you need information about a disease's prognosis, cohort or case-control studies will likely offer the best insights into your question. The table below is a good place to begin when looking for resources in databases such as PubMed Central, CINHAL, MEDLINE Ultimate. 

When using the Jerry Falwell Library's Medical Databases, you can structure your searches to include keywords such as "cohort studies, "randomized control trial," or "prospective study" to find relevant resources. This tutorial also describes how to locate specific resource types. 

 

Table outlining research question types and best research methodologies, with examples.

 

Table adapted from Hoffman, T., Bennett, S., & Del Mar, C. (2013). "Information needs, asking, questions, and some basics of research studies." Evidence-based practice across the health professions (3rd ed.), 18. Elsevier. and the University of Canberra's Evidence-Based Practice in Health Library Guide. 

Hierarchy of Evidence

As you are defining your PICO question and searching for supporting resources, you may need to consult several different article types (case-control studies, randomized control trials, etc.). For example, if you are studying Type 1 Diabetes in children, you may need information related to frequency, prognosis, and the diagnosis of the disease. As described in the section above, different clinical questions are best answered by certain study designs, so consulting articles with different research frameworks is a good way to approach different facets of your research question.

While all scholarly research has value, researchers employ varying levels of methodological rigor when conducting their research. The hierarchy of evidence pyramid is a visual ranking of health research methods. Using the hierarchy of evidence pyramid can help you answer the question: "What is the best evidence available?" The diagram below is based on guidance provided by the National Health and Medical Research Council. 

Clinical hierarchy of evidence
Duke University Medical Center Library & Archives. (2022). Hierarchy of Evidence [Digital image]. Evidence-Based Practice: Study Design. https://guides.mclibrary.duke.edu/ebm/studydesign
 
Different hierarchies exist for different clinical questions, but generally, systematic reviews or meta-analyses are placed at the top of the hierarchy, with opinion pieces occupying the lowest level of clinical evidence. Depending on your information need, you may use a combination of filtered resources (secondary studies) and unfiltered resources (primary research studies). 
 
Filtered versus Unfiltered Information 
  • Filtered Information: Research articles (secondary) that appraise and evaluate the quality of a primary study and its potential application in clinical practice. Databases such as Cochrane Library specialize in filtered resources. 
  • Unfiltered Information: Primary (original) research studies that have not been synthesized or aggregated. Because these articles represent a single study, they do not represent a consensus across the literature, so the evidence provided must be used with caution in clinical practice. 

Kendall S. (2008). Evidence-based resources simplified. Canadian family physician Medecin de famille canadien, 54(2), 241–243.

What are systematic reviews and meta-analyses? Systematic reviews, with or without meta-analysis, are studies that analyze the results of multiple primary research studies. Systematic reviews use a schema such as PRISMA to identify relevant research literature, and the article's authors then synthesize and interpret the literature in the form of a systematic review. It is important to keep the following in mind: 

  • The systematic review process is rigorous, so this process can take years to complete; therefore, keep in mind the value of primary studies or of other more recent evidence. 
  • Keep in mind that a large research study (randomized control trial, cohort studies, etc.) might provide more substantial clinical evidence than a systematic review of several smaller studies. 

What are primary research studies? Primary (original) research studies seek to answer a clinical question by employing a specific research design, such as a randomized control trial or a qualitative study. When choosing primary research studies, evaluate the study's research design (methodology), as a study is only as good as the framework employed. 

References

Hoffman, T., Bennett, S., & Del Mar, C. (2013). Evidence-based practice across the health professions (3rd ed.). Elsevier.

Kendall S. (2008). Evidence-based resources simplified. Canadian family physician Medecin de famille canadien, 54(2), 241–243.

This guide is also partially based on information found in the University of Canberra's Evidence-Based Practice in Health guide. 

Evidence Based Resources

These resources have significant sub-sections of evidence-based research.