|Level of Evidence||Strength||Grade|
|Level 1 Studies||Strong||A|
|Level 2, 3, or extrapolations from Level 1||Moderate||B|
|Level 4 or extrapolations from Level 2, 3||Limited/Weak||C|
|Level 5 or inconsistent, inconclusive studies from any level||Incomplete/Inconsistent||D|
(Table adapted from CEBM and Forrest, 2009)
Clinical Practice Guidelines: Recommendations for clinical care. Usually informed by a knowledge synthesis (systematic review) and clinical expertise.
Systematic Review: Synthesis of evidence (i.e. articles) on a defined topic/question. The group of researchers will evaluate and analyze the evidence to inform clinical practice.
Meta-Analysis: Usually follows a systematic review. Combines the data from multiple (similar) studies to address SR topic/question.
Randomized Controlled Trials: Assesses a specific intervention by comparing two similar groups, with one receiving the intervention and the other not (usually called a placebo). By doing this, researchers can assess the differences attributed to the intervention.
Cohort Studies: Observational studies regarding the association between a specific exposure or risk factor and the development of a clinical condition.
Case Control Studies: Observational studies regarding associations between a specific clinical condition and possible risk factors.
Cross-Sectional Studies: Observational studies that gather information at one point and time on the prevalence of health outcome(s), or exposure(s), or both.
Case Reports: Report of a single patient, or treatment of several patients. There is no research design for case reports. They can be beneficial in identifying new health conditions.
Narrative/Literature Reviews: Overview of previous studies on a specific topic. Not as rigorous as a knowledge synthesis (i.e. systematic review) and there is no research design.
Editorials: Opinion piece in an academic journal that is not peer reviewed. No research design in an editorial.