Table 2.

Levels of evidence approach [22]

Level of evidence	Criteria
Strong	Consistenta findings from 3 or more high-quality studies
Moderate	Consistenta findings from at least 1 high-quality and 1 low-quality study
Limited	Consistenta findings in > 1 low-quality study or only one study available
Conflicting	Inconsistent evidence in multiple studies irrespective of study quality
No evidence	No studies found

^aConsistent was interpreted as > 60% of studies trending from the line of no effect in either direction