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NSG 628: Practice Inquiry II: Design and Methods

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What is Evidence-Based Practice?

As stated by Melnyk et al.:

EBP is a problem-solving approach to the delivery of health care that integrates the best evidence from well-designed studies and patient care data, and combines it with patient preferences and values and nurse expertise (pg. 51).

Melnyk, B. M., Fineout-Overholt, E., Stillwell, S. B., & Williamson, K. M. (2009). Igniting a spirit of inquiry: An essential foundation for evidence-based practice; how nurses can build the knowlede and skills they need to implement EBP. The American Journal of Nursing, 109(11), 49.


What is PICOS?

One of the steps in the EBP process includes locating the best-available evidence. To help with this step, PICOS was developed. PICOS is a mnemonic tool to help researchers formulate a searchable question. This tool was developed by McMaster University and Health Evidence™

Population/Patient/Problem For which group do you need information?

Intervention What medical event do you need to study the effect of?

Comparison What is the evidence that the intervention produces different results than a different or no intervention?

Outcome What is the effect of the intervention?

Setting/Study Type Where is the research done (e.g., ambulatory setting) or type of study (e.g., RCT)?          

Levels of Evidence

In evidence-based practice, nurses use levels of evidence to evaluate and assess a study's strengths and weakness. This can lead to evidence-based changes to clinical practice. 


Level 1     Systematic reviews or meta-analyses
Level 2     Randomized controlled trials
Level 3     a. Cohort studies (with control group)
                  b. Case-controlled 
                  c. Observational studies (without control group)
Level 4     Expert opinion, physiology bench research, or consensus


PETERSON, M. H., BARNASON, S., DONNELLY, B., HILL, K., MILEY, H., RIGGS, L., & WHITEMAN, K. (2014). Choosing the Best Evidence to Guide Clinical Practice: Application of AACN Levels of Evidence. Critical Care Nurse, 34(2), 58–68.  doi:10.4037/ccn2014411

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