| 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 |
[16] Morphine syrup (Adults: palliative dyspnoea): Barnes H, McDonald J, Smallwood N, Manser R. Opioids for the palliation of refractory breathlessness in adults with advanced disease and terminal illness. Cochrane Database Syst Rev. 2016 Mar 31;3:CD011008. https://www.ncbi.nlm.nih.gov/pubmed/27030166
Morphine syrup (Adults: palliative dyspnoea): National Department of Health: Affordable Medicines, EDP- PHC. Medicine Review: Morphine, oral for palliative dyspnoea in adults and children, September 2017. http://www.health.gov.za/