Abstract O-023 Table 1

Modified level of evidence scale for NI research

Level of evidenceStudy type
1Systematic reviews or meta-analyzes of randomized controlled trials or individual randomized controlled trials
2Systematic reviews or meta-analyzes of predominantly prospective studies, or individual prospective studies
3Systematic reviews or meta-analyzes of predominantly retrospective studies, or restrospective case-control studies
4Retrospective non-case-control studies of 10 or more patients
5Case reports, case series of 9 patients or less, national or state retrospective database studies, animal studies, or other non-human studies