| 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 |
[9] Magnesium sulfate: Kew KM, Kirtchuk L, Michell CI. Intravenous magnesium sulfate for treating adults with acute asthma in the emergency department. Cochrane Database Syst Rev.2014 May 28;5:CD010909. http://www.ncbi.nlm.nih.gov/pubmed/24865567
Magnesium sulfate: Goodacre S, Cohen J, Bradburn M, Gray A, Benger J, Coats T; 3Mg Research Team. Intravenous or nebulised magnesium sulfate versus standard therapy for severeacute asthma (3Mg trial): a double-blind, randomised controlled trial. LancetRespir Med. 2013 Jun;1(4):293-300. http://www.ncbi.nlm.nih.gov/pubmed/24429154