Table
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Journal of Bone and Joint Surgery levels of evidence for rating the quality of clinical studies. Studies are classified as one of four study types with five possible levels. The criteria for assignment are contained within the cells of the table. |
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Types of Studies |
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Therapeutic Studies — |
Prognostic Studies — |
Diagnostic Studies — |
Economic and Decision Analyses — |
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Investigating the results of treatment |
Investigating the outcome of disease |
Investigating a diagnostic test |
Developing an economic or decision model |
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Level I |
Randomized Trial Statistically significant difference. No statistically significant difference but narrow confidence intervals Systematic Review2 of Level I RCTs (and studies were homogenous) |
1. Prospective study1 2. Systematic Review2 of Level I studies |
Testing of previously developed diagnostic criteria on consecutive patients (with universally applied reference "gold" standard) Systematic review2 of Level I studies |
Clinically sensible costs and alternatives; values obtained from many studies, with multiway sensitivity analyses Systematic review2 of Level I studies |
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Level II |
Prospective cohort study3 Poor quality RCT (e.g. < 80% follow-up) Systematic review2(a) Level II studies(b) non-homogeneous Level 1 studies |
Retrospective4 study Untreated controls from an RCT
Systematic review2 of Level II studies |
Development of diagnostic criteria on consecutive patients(with universally applied reference"gold" standard) Systematic review2 of Level II studies |
Clinically sensible costs and alternatives; values obtained from limited studies; with multiway sensitivity analyses Systematic review2 of Level II studies |
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Level III |
Case control study5 Retrospective4 cohort study Systematic review2 of Level III studies |
Study of non- consecutive patients; without consistently applied reference"gold" standard Systematic review2 of Level III studies |
Analyses based on limited alternatives and costs; and poor estimates Systematic review2 of Level III studies |
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Level IV |
Case Series (no, or historical, control group) |
Case series |
Case-control study Poor reference standard |
Analyses with no sensitivity analyses |
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Level V |
Expert Opinion |
Expert Opinion |
Expert Opinion |
Expert Opinion |
1. All patients were enrolled at the same point in their disease (inception cohort) with a greater than or equal to 80% follow-up of enrolled patients
2. A combination of results from two or more prior studies.
3. Patients compared with a control group of patients treated at same time and institution.
4. The study was initiated after treatment performed.
5. Patients with a particular outcome called "cases"; e.g. failed total arthroplasty compared to those who did not have outcome called "controls", e.g. non-failed total hip arthroplasty.
Introducing Levels of Evidence to The Journal J Bone Joint Surg Am 2003 85: 1-3