Chapter004

Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins
Chapter 4: Critically Appraising
Knowledge for Clinical Decision
Making

The Need for Critical Appraisal
• It is vital to discern biased evidence from unbiased,
reliable from unreliable
• Practice that is based on flawed evidence cannot be
considered EBP

Knowledge Sources
• In the past, practice was based largely on tradition, logic,
and expertise
• Research Utilization (RU) movement began to change
this
− RU emphasized the use of single studies, however
• The process for generating practice-based evidence (e.g.,
quality improvement data) has improved

Weighing the Evidence
• Practitioners take into account the validity and
reliability of the specific evidence
• Reliance on inexplicit or inferior knowledge sources
(tradition; trial and error) is rapidly becoming
unacceptable

Knowledge Sources for EBP
1. Valid research evidence
− The primary basis of clinical decisions
2. Clinical expertise
− To best use research by filling in gaps and
combining it with practice-based evidence to tailor
clinical actions for individual patients’ contexts
3. Patient choices and concerns
− For determining the acceptability of evidence-based
care to the individual patient
• The main criterion is certainty

Question
• Which of the following sources of knowledge would a
nurse prioritize when determining the turning schedule
for an immobilized patient?
a. The traditional practice on the unit
b. The nurse’s knowledge of skin breakdown
c. The preferences of the patient and the patient’s family
d. A clinical practice guideline for preventing skin
breakdown

Answer
• d. A clinical practice guideline for preventing skin
breakdown
• Rationale: EBP encompasses patient preferences and the
clinical expertise of individual practitioners, but the
primary source of knowledge is research evidence.
Clinical practice guidelines synthesize this evidence in
order to guide practice.

Rating the Strength of Evidence
• Not necessarily synonymous with “hierarchy of evidence”
− High-level study design does not necessarily mean
high quality
• Grading the strength of a body of evidence addresses
three domains – quality, quantity, and consistency

Rating the Strength of a Body of Evidence
• Quality: the extent to which a study’s design, conduct,
and analysis has minimized selection, measurement, and
confounding biases (internal validity)
• Quantity: the number of studies that have evaluated the
question, overall sample size across all studies,
magnitude of the treatment effect, strength from
causality assessment, such as relative risk or odds ratio
• Consistency: whether investigations with both similar
and different study designs report similar findings
(requires numerous studies)

What is Meant by “Evidence”
• Research evidence
• Clinical knowledge gained via the individual practitioner’s
experience
• Patients’ and practitioners’ preferences
• Basic principles from logic and theory

Question
• Tell whether the following statement is true or false.
• A post-operative patient’s statement that Dilaudid
(hydromorphone) has been ineffective in treating her
pain can be considered a form of evidence.

Answer
• True
• Rationale: Patient preferences and experiences are an
important consideration and are a form of evidence.
While the patient’s preference does not likely constitute
the “final word” on treatment choices, it must be weighed
carefully and integrated into the nurse’ choice of
intervention.

Internal Evidence
• Evidence that is generated by outcomes management,
quality improvement, or EBP implementation projects
• Aimed at improving outcomes at the site where
improvement efforts are conducted
• Quality Indicator Systems:
− AHRQ National Healthcare Quality Report
− National Quality Forum (NQF)
− National Database of Nursing Quality Indicators®
(NDNQI®)

Question
• Tell whether the following statement is true or false.
• Internal evidence is characterized by findings that are
applicable and generalizable to multiple practice settings.

Answer
• False
• Rationale: Unlike external evidence, the generation of
internal evidence is intended to improve clinical practice
and patient outcomes within the local setting that it is
conducted.

Combining Internal and External
Evidence
• The PDSA Cycle
1. Plan: Plan the change and observation
2. Do: Try out the change on a small scale
3. Study: Analyze the data and determine what was
learned
4. Act: Refine the change based on what was learned
and repeat the testing

Chapter004

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Chapter004