| 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 |
[14] Inhaled corticosteroids: Suissa S, Ernst P, Benayoun S, Baltzan M, Cai B. Low-dose inhaled corticosteroids and the prevention of death from asthma. N Engl J Med. 2000 Aug 3;343(5):332-6. https://www.ncbi.nlm.nih.gov/pubmed/10922423
Inhaled corticosteroids: Busse WW, Pedersen S, Pauwels RA, Tan WC, Chen YZ, Lamm CJ, O'Byrne PM; START Investigators Group. The Inhaled Steroid Treatment As Regular Therapy in Early Asthma (START) study 5-year follow-up: effectiveness of early intervention with budesonide in mild persistent asthma. J Allergy ClinImmunol. 2008May;121(5):1167-74. http://www.ncbi.nlm.nih.gov/pubmed/18405951
Inhaled corticosteroids: Reddel HK, Busse WW, Pedersen S, Tan WC, Chen YZ, Jorup C, Lythgoe D, O'Byrn PM. Should recommendations about starting inhaled corticosteroid treatment for mild asthma be based on symptom frequency: a post-hoc efficacy analysis of the START study. Lancet. 2017 Jan 14;389(10065):157-166. https://www.ncbi.nlm.nih.gov/pubmed/27912982
Inhaled corticosteroids: Global Initiative for Asthma. Global Strategy for Asthma Management and Prevention, 2019. http://www.ginasthma.org/