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Charlotte AHEC Library Guide for Nurses: Evidence Based Practice

What is Evidence Based Practice (EBP)?

Evidence Based Practice (EBP) in nursing (sometimes referred to as Evidence Based Nursing, or EBN) is the idea that nursing practices should be based on scientific evidence, with the goal of eliminating unreliable or outdated practices in favor of more effective ones. This moves nursing practices from tradition and intuition-based experiences to those based on reliable scientific research.


The PICO(TS) process is a mnemonic used in EBP to frame and answer a clinical or health care related question, or to develop literature search strategies.

P – Patient, Problem or Population
I – Intervention
C – Comparison, control or comparator
O – Outcome(s)

Some authors suggest adding T and S, as follows:

T - Timing, duration or date of publication
S - Study type

There are also several alternatives to the PICO process, such as SPICE and PECO. 

Levels of Evidence


Levels of evidence from most authoritative (Level 1) to least authoritative (Level 7).

Level 1 Evidence from a systematic review or meta-analysis of all relevant randomized controlled trials (RCTs) or evidence-based clinical practice guidelines based on systematic reviews of RCTs
Level 2 Evidence obtained from a well-designed RCT
Level 3 Evidence obtained from well-designed controlled trials without randomization
Level 4 Evidence from well case-control and cohort studies 
Level 5 Evidence from systematic reviews of descriptive and qualitative studies
Level 6 Evidence from a single descriptive or qualitative study 
Level 7 Evidence from the opinion of authorities and/or reports of expert committees

What is a systematic review?

A systematic review attempts to identify, appraise and synthesize all the empirical evidence that meets pre-specified eligibility criteria to answer a specific research question. Researchers conducting systematic reviews use explicit, systematic methods that are selected with a view aimed at minimizing bias, to produce more reliable findings to inform decision making. (Source: Cochrane Library)