Table 10.

Hierarchy of strength of evidence for therapeutic decisions [slightly modified after [14]]

Level	Description
I	Systematic review of randomized controlled trials (RCTs)
II	Article about an RCT
III	Article about an experimental study without randomization; cohort study; case-control-study
IV	Article about a non-experimental study (cross-sectional study; case series; case report)
V	Narrative review or expert opinion (based on clinical experience) without explicit clinical appraisal (e.g., statements, editorials; expert commentaries to published articles; interviews with experts, brief references to NTI-tss in articles; commercial-like reviews)