Level of evidence

Type of study

I

a

Systematic Review of Randomized Clinical Trials (RCTs)

b

Systematic Review of non-Randomized Clinical Trials

II

a

Individual RCT

b

Non-randomized trial

III

Systematic Review of correlational/observational studies

IV

Correlational/observational study

V

Systematic Review of descriptive, qualitative, physiological studies

VI

Individual descriptive/qualitative/physiological study

VII

Expert opinion, expert committees