Evidence obtained from meta-analysis or systematic review of randomized controlled trials
|Ib||Evidence obtained from at least one randomized controlled trial.|
|IIa||Evidence obtained from at least one well-designed controlled study without randomization.|
Evidence obtained from at least one other type of well-designed quasi- experimental study, without randomization.
|III||Evidence obtained from well-designed, non-experimental descriptive studies, such as comparative studies, correlation studies and case studies.|
Evidence obtained from expert committee reports or opinions and/or clinical experiences of respected authorities