| 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] Hydrocortisone, IV: Cunnington D, Smith N, Steed K, Rosengarten P, Kelly AM, Teichtahl H. Oral versus intravenous corticosteroids in adults hospitalised with acute asthma. PulmPharmacol Ther. 2005;18(3):207-12.http://www.ncbi.nlm.nih.gov/pubmed/15707855