Evidence Ratings

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Read about the levels of evidence here.

ASIPP

ASIPP evidence ratings are preferred when assessing evidence in WikiMSK.

Modified grading of qualitative evidence with best evidence synthesis for therapeutic interventions

Therapy/Prevention/Etiology/Harm
Level I	Multiple relevant high quality randomized controlled trials
Level II	At least one relevant high quality randomized controlled trial or multiple relevant moderate or low quality randomized controlled trials
Level III	At least one relevant moderate or low quality randomized controlled trial study or At least one relevant high quality non-randomized trial or observational study with multiple moderate or multiple moderate or low quality observational studies
Level IV	Multiple moderate or low quality relevant observational studies
Level V	Opinion or consensus of large group of clinicians and/or scientists.

Modified grading of qualitative evidence with best evidence synthesis for diagnostic accuracy

Diagnosis
Level I	Multiple high quality diagnostic accuracy studies
Level II	At least one high quality diagnostic accuracy study or multiple moderate or low quality diagnostic accuracy studies
Level III	At least one moderate quality diagnostic accuracy study in addition to low quality studies
Level IV	Multiple relevant low quality diagnostic accuracy studies
Level V	Opinion or consensus of large group of clinicians and/or scientists.

Based on ASIPP criteria Template: {{ASIPP|rating}}

SORT

Strength-of-Recommendation Taxonomy

Code	Definition
A	Consistent, good-quality patient-oriented evidence
B	Inconsistent or limited-quality patient-oriented evidence
C	Consensus, disease-oriented evidence, usual practice, expert opinion, or case series for studies of diagnosis, treatment, prevention, or screening

Patient-oriented evidence measures outcomes that matter to patients: morbidity, mortality, symptom improvement, cost reduction, and quality of life.

Disease-oriented evidence measures immediate, physiologic, or surrogate end points that may or may not reflect improvements in patient outcomes (e.g. blood pressure, blood chemistry, physiologic function, pathologic findings).

Template: {{SORT|rating}}

GRADE

Grading of Recommendations Assessment, Development and Evaluation (GRADE)

Code	Quality of Evidence	Definition
A	High	Further research is very unlikely to change our confidence in the estimate of effect. Several high-quality studies with consistent results In special cases: one large, high-quality multi-centre trial
B	Moderate	Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate. One high-quality study Several studies with some limitations
C	Low	Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate. One or more studies with severe limitations
D	Very Low	Any estimate of effect is very uncertain
Expert Opinion	No direct research evidence	One or more studies with very severe limitations

Source: GRADE (Grading of Recommendations Assessment, Development and Evaluation) Working Group 2007 1 (modified by the EBM Guidelines Editorial Team)

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CEBM

Centre for Evidence-Based Medicine, Oxford For the most up-to-date levels of evidence, see www.cebm.net/?o=1025

Therapy/Prevention/Etiology/Harm
1a	Systematic reviews (with homogeneity ) of randomized controlled trials
1a-	Systematic review of randomized trials displaying worrisome heterogeneity
1b	Individual randomized controlled trials (with narrow confidence interval)
1b-	Individual randomized controlled trials (with a wide confidence interval)
1c	All or none randomized controlled trials
2a	Systematic reviews (with homogeneity) of cohort studies
2a-	Systematic reviews of cohort studies displaying worrisome heterogeneity
2b	Individual cohort study or low quality randomized controlled trials (<80% follow-up)
2b-	Individual cohort study or low quality randomized controlled trials (<80% follow-up / wide confidence interval)
2c	'Outcomes' Research; ecological studies
3a	Systematic review (with homogeneity) of case-control studies
3a-	Systematic review of case-control studies with worrisome heterogeneity
3b	Individual case-control study
4	Case-series (and poor quality cohort and case-control studies)
5	Expert opinion without explicit critical appraisal, or based on physiology, bench research or 'first principles'

Diagnosis
1a	Systematic review (with homogeneity) of Level 1 diagnostic studies; or a clinical rule validated on a test set.
1a-	Systematic review of Level 1 diagnostic studies displaying worrisome heterogeneity
1b	Independent blind comparison of an appropriate spectrum of consecutive patients, all of whom have undergone both the diagnostic test and the reference standard; or a clinical decision rule not validated on a second set of patients
1c	Absolute SpPins And SnNouts (An Absolute SpPin is a diagnostic finding whose Specificity is so high that a Positive result rules-in the diagnosis. An Absolute SnNout is a diagnostic finding whose Sensitivity is so high that a Negative result rules-out the diagnosis).
2a	Systematic review (with homogeneity) of Level >2 diagnostic studies
2a	Systematic review of Level >2 diagnostic studies displaying worrisome heterogeneity
2b	Any of 1)independent blind or objective comparison; 2)study performed in a set of non-consecutive patients, or confined to a narrow spectrum of study individuals (or both) all of whom have undergone both the diagnostic test and the reference standard; 3) a diagnostic clinical rule not validated in a test set.
3a	Systematic review (with homogeneity) of case-control studies
3a	Systematic review of case-control studies displaying worrisome heterogeneity
4	Any of 1)reference standard was unobjective, unblinded or not independent; 2) positive and negative tests were verified using separate reference standards; 3) study was performed in an inappropriate spectrum of patients.
5	Expert opinion without explicit critical appraisal, or based on physiology, bench research or 'first principles'

Prognosis
1a	Systematic review (with homogeneity) of inception cohort studies; or a clinical rule validated on a test set.
1a-	Systematic review of inception cohort studies displaying worrisome heterogeneity
1b	Individual inception cohort study with > 80% follow-up; or a clinical rule not validated on a second set of patients
1c	All or none case-series
2a	Systematic review (with homogeneity) of either retrospective cohort studies or untreated control groups in RCTs.
2a-	Systematic review of either retrospective cohort studies or untreated control groups in RCTs displaying worrisome heterogeneity
2b	Retrospective cohort study or follow-up of untreated control patients in an RCT; or clinical rule not validated in a test set.
2c	'Outcomes' research
4	Case-series (and poor quality prognostic cohort studies)
5	Expert opinion without explicit critical appraisal, or based on physiology, bench research or 'first principles'

Template| {{CEBM|rating}}

Practice Guidelines (various)

Key to interpretation of practice guidelines

Agency for Healthcare Research and Quality
A	There is good research-based evidence to support the recommendation
B	There is fair research-based evidence to support the recommendation.
C	The recommendation is based on expert opinion and panel consensus
X	There is evidence of harm from this intervention

USPSTF Guide to Clinical Preventive Services
A	There is good evidence to support the recommendation that the condition be specifically considered in a periodic health examination
B	There is fair evidence to support the recommendation that the condition be specifically considered in a periodic health examination
C	There is insufficient evidence to recommend for or against the inclusion of the condition in a periodic health examination, but recommendations may be made on other grounds
D	There is fair evidence to support the recommendation that the condition be excluded from consideration in a periodic health examination
E	There is good evidence to support the recommendation that the condition be excluded from consideration in a periodic health examination.

University of Michigan Practice Guideline
A	Randomized controlled trials
B	Controlled trials, no randomization
C	Observational trials
D	Opinion of the expert panel

Other guidelines
A	There is good research-based evidence to support the recommendation
B	There is fair research-based evidence to support the recommendation
C	The recommendation is based on expert opinion and panel consensus
X	There is evidence that the intervention is harmful