| 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 |
[21] Benzathine benzylpenicillin (late latent syphilis/of unknown duration): Workowski KA, Bolan GA. Workowski KA, Bolan GA; Centers for Disease Control and Prevention. Sexually transmitted diseases treatment guidelines, 2015 [published correction appears in MMWR Recomm Rep. 2015 Aug 28;64(33):924] MMWR Recomm Rep. 2015;64(RR-03):1‐137. https://pubmed.ncbi.nlm.nih.gov/26042815/
Benzathine benzylpenicillin (late latent syphilis/of unknown duration): World Health Organization: WHO Guidelines for the treatment of Treponema palladum (syphilis), 2016.
https://www.who.int/reproductivehealth/publications/rtis/syphilis-treatment-guidelines/en/