| Level I | Good quality evidence |
Systematic review of RCTs with consistent findings High quality individual RCT |
| Level II |
Limited quality patient orientated evidence |
Systematic review of lower quality studies or studies with inconsistent findings Low quality clinical trial Cohort studies Case-control studies |
| Level III | Other |
Consensus guidelines, extrapolations from bench research, usual practice, opinion, disease-oriented evidence (intermediate or physiologic outcomes only), or case series |
[25] Activated charcoal:Bradberry SM, Vale JA. Multiple-dose activated charcoal: a review of relevant clinical studies. J ToxicolClinToxicol. 1995;33(5):407-16. Review.http://www.ncbi.nlm.nih.gov/pubmed/7650765
Whole bowel irrigation:Mayer AL, Sitar DS, Tenenbein M. Multiple-dose charcoal and whole-bowel irrigation do not increase clearance of absorbed salicylate. Arch Intern Med. 1992 Feb;152(2):393-6. http://www.ncbi.nlm.nih.gov/pubmed/1739372