| 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 |
[15] Factor IX: World Federation of Haemophilia. 2012. Guidelines for Management of Haemophilia. http://www1.wfh.org/publication/files/pdf-1472.pdf
Factor IX: Mahlangu JN, Gilham A. Guideline for the Treatment of Haemophilia in South Africa. S Afr Med J 2008; 98: 125-140. http://www.samj.org.za/index.php/samj/article/view/336/723