| 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 |
[7] Amitriptyline, oral: National Department of Health, Essential Drugs Programme: Adult Hospital Level STGs and EML, 2019. http://www.health.gov.za/
Amitriptyline, oral: Dworkin RH, Schmader KE. Treatment and prevention of postherpetic neuralgia. Clin Infect Dis. 2003 Apr 1; 36(7):877-82. https://www.ncbi.nlm.nih.gov/pubmed/12652389