Evidence-Based Medicine
Copyright ©The Author(s) 2016.
World J Hepatol. Sep 8, 2016; 8(25): 1075-1086
Published online Sep 8, 2016. doi: 10.4254/wjh.v8.i25.1075
Table 2 Levels of evidence according to the study design
Level of evidenceDescription
Type IEvidence obtained at least from one well-designed, randomized, controlled1 trial or from a systematic review of randomized clinical studies
Type IIII-1 evidence obtained from non-randomized, prospective, controlled1 studies
II-2 evidence obtained from cohort observational studies2 or case-control studies, preferably multi-centric
II-3 evidence obtained from case series
Type IIIOpinion of authorities on the subject matter based on expertise, expert committees, case reports, pathophysiological studies or basic science studies