Level of evidence, strength of recommendations, and patient-centered care
Describe the concept of “levels of evidence
(LOE)” and explain which research study
designs lead to certain levels of evidence.
2. Define the term “strength of recommendation
taxonomies (SORT)” and give examples of two
organizations’ SORT criteria.
3. Evaluate clinical practice guidelines by using
LOE and SORT, and summarize the evidencebased applicability of these guidelines.
While covering the ER, an 18 year-old male
presents with acute shortness of breath. His
symptoms had present over the past 8 hours,
but acutely worsened 30 minutes ago.
On arrival, he is tachypneic, using accessory
muscles, and only able to speak in short
sentences. His RR is 36, with supra-sternal
retractions. Pulse Ox is 94%, and his peak
flow is <40% predicted.
The patient is placed on supplemental O2,
and he is given 3 combined
albuterol/ipratropium nebulizer treatments.
Despite this, he does not improve
What are your next treatment options?
How will you know if what you *think* is the
next step will be an effective next step?
How can we quickly and efficiently assess the
quality of evidence?
Level of evidence (LOE)
Strength of recommendation (SOR)
Provides a quick overview
How reliable is the study’s findings?
How much bias is likely?
How “good” is this study?
Study design affects likely LOE: more robust
studies usually lead to better LOE
Review of study design:
Case series or case reports
Also: reviews and syntheses of prior studies
Oxford Centre for Evidence-Based Medicine
Divides criteria by the question being asked
A “gold standard”?
Level 1 is the highest/least-biased/”best”
evidence, usually from RCTs, systematic reviews,
Level 5 evidence is mechanism-based reasoning.
Assesses the usefulness of clinical
Usually seen in the context of point-of-care
tools, evidence-based summaries, etc.
Provides a patient-centered review of clinical
Incorporates patient-centered outcomes and
level of evidence
Disease-oriented outcomes: “These outcomes
include intermediate, histopathologic, physiologic, or
surrogate results (ie, blood sugar, blood pressure, flow
rate, coronary plaque thickness) that may or may not
reflect improvements in patient outcomes”
Patient-centered outcomes: “These are outcomes
that matter to patients and help them live longer or
better lives, including reduced morbidity, reduced
mortality, symptom improvement, improved quality
of life, or lower cost”
Disease-oriented outcomes: Measurements
that scientifically or physiologically “make
sense” in terms of disease management (BP,
A1c, FEV1, etc.); surrogate outcomes.
Patient-centered outcomes: Events that
actually make a tangible difference in
patients’ lives (hospitalizations, death, etc.)
Studies that show apparently beneficial
changes in surrogate outcomes may not
improve (or may worsen) patient outcomes
Surrogate outcomes are easier to study, and
those studies are more common
SOR taxonomies allow a rapid overview of
Study designs also tend to predispose to
certain SOR…if those studies used patientoriented outcomes, better studies lead to
Different organizations use different
approaches to define SOR
Are you familiar with any particular SOR
A, B, C, D, I
A, B, C
strong recommendation, recommendation, option, no
ACP = USPSTF
How would you determine the next steps in
treating our patient?
Search for guidelines that answer the clinical
question (5 mins)
Report back re: what you found and the
quality of the evidence
What is the LOE or SOR associated with the
guidelines you found?
How confident are you in these guidelines?
LOE and SORT will NOT
Provide definitive judgment
Provide definitive treatment recommendations
▪ the study population represents your population
▪ the outcome is patient-centered and clinically-relevant,
treatment is appropriate
▪ no other treatment is superior
LOE and SOR are interrelated and
LOE focuses on individual studies, SOR on
LOE and SOR help guide clinical decisionmaking, but do not dictate it
“What does this mean?”
How good is this evidence?
How much can I trust it?
“What do I do with it?”
How can I best use this evidence?
What does this evidence mean to me and my