Tabled 1Levels of Evidence for Primary Research
|Types of Studies|
|Therapeutic Studies-Investigating the Results of Treatment||Prognostic Studies-Investigating the Effect of a Patient Characteristic on the Outcome of Disease||Diagnostic Studies Investigating a Diagnostic Test||Economic and Decision Analyses-Developing an Economic or Decision Model|
|Level IV||Case series|
|Level V||Expert opinion||Expert opinion||Expert opinion||Expert opinion|
Reprinted with permission. Copyright © 2005 by The Journal of Bone and Joint Surgery, Incorporated
1 A complete assessment of the quality of individual studies requires critical appraisal of all aspects of the study design.
2 A combination of results from two or more prior studies.
3 Studies provided consistent results.
4 Study was started before the first patient enrolled.
5 Patients treated one way (e.g., with cemented hip arthroplasty) compared with patients treated another way (e.g., with cementless hip arthroplasty) at the same institution.
6 Study was started after the first patient enrolled.
7 Patients identified for the study on the basis of their outcome (e.g., failed total hip arthroplasty), called “cases,” are compared with those who did not have the outcome (e.g., had a successful total hip arthroplasty), called “controls.”
8 Patients treated one way with no comparison group of patients treated another way.
© 2005 Published by Elsevier Inc. All rights reserved.