| 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 |
[6] The Task Force on the Prevention, Diagnosis, and Treatment of Infective Endocarditis of the European society of Cardiology. Guidelines on the prevention, diagnosis, and treatment of infective endocarditis. European Heart Journal. 2009;30:2369-2413.