TABLE 2.

The levels of evidence are based on Cochrane⁵⁹ methodology

LEVELS OF EVIDENCE	DEFINITION
1	Evidence obtained from a systematic review of all relevant randomized controlled trials.
2	Evidence obtained from at least one properly designed randomized controlled trial.
3.1	Evidence obtained from well-designed, pseudo-randomized controlled trials
3.2	Evidence obtained from comparative studies with concurrent controls and allocation not randomized, cohort studies, case-control studies, or interrupted time series with a control group.
3.3	Evidence obtained from comparative studies with historical control, two or more single arm studies, or interrupted time series without a parallel control group.
4	Evidence obtained from case studies, either post-test or pretest/ post-test