| 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 |
[8] Doxycycline, oral (Early syphilis treatment - penicillin allergic/benzathine benzylpenicillin unavailable): World Health Organization. WHO guidelines for the treatment of Treponemapallidum (syphilis), 2016. http://apps.who.int/iris/bitstream/10665/249572/1/9789241549806-eng.pdf