| 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 |
[32] Treatment failure > 48 hours requiring referral: Chapman AS, Bakken JS, Folk SM, Paddock CD, Bloch KC, Krusell A, et al: Tickborne Rickettsial Diseases Working Group; CDC. Diagnosis and management of tickborne rickettsial diseases: Rocky Mountain spotted fever, ehrlichioses, and anaplasmosis--United States: a practical guide for physicians and other health-care and public health professionals. MMWR Recomm Rep. 2006 Mar 31;55(RR-4):1-27. https://www.ncbi.nlm.nih.gov/pubmed/16572105