| 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 |
[27] Metronidazole, IV: World Health Organisation. Technical note: Current recommendations for treatment of tetanus during humanitarian emergencies, January 2010. https://www.who.int/diseasecontrol_emergencies/who_hse_gar_dce_2010_en.pdf