| Evidence classification method： |
Table 1 Standard of level of evidence
Level of evidence Standard
I Based on high-level prospective randomized controlled clinical trials, observational studies or meta-analyses with large sample sizes, internationally-recognized current guidelines and consensus statements, published guidelines and consensus statements from national societies or associations, Chinese population-based studies of the above types published in SCI journals, MEDLINE journals, and Chinese series journals
II Based on low-level randomized clinical trials, well-designed non-controlled trials or cohort studies, inter-continental professional association guidelines and international conference expert consensus statements, published guidelines and consensus statements from national regional societies or associations, Chinese population-based studies of the above types published in PKU core journals
III Based on case-control studies or retrospective studies, published guidelines and consensus statements from national professional associations, and provincial societies or associations, Chinese population-based studies of the above types published in source journals for Chinese scientific and technical papers and citations
IV Based on case reports, scientific hypotheses, regional expert consensus statements and published guidelines and consensus statements from national local societies or associations, Chinese population-based studies of the above types published in non-aforementioned core journals |
