| 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 |
[10] NSAIDs, oral (adults - chronic cancer pain): Derry S, Wiffen PJ, Moore RA, McNicol ED, Bell RF, Carr DB, McIntyre M, Wee B. Oral nonsteroidal anti-inflammatory drugs (NSAIDs) for cancer pain in adults. Cochrane Database Syst Rev. 2017 Jul 12;7:CD012638. https://www.ncbi.nlm.nih.gov/pubmed/28700091
Ibuprofen, oral (ceiling effect): National Department of Health, Essential Drugs Programme: Adult Hospital level STG, 2015. http://www.health.gov.za/
Ibuprofen (ceiling effect): Laska EM, Sunshine A, Marrero I, Olson N, Siegel C, McCormick N. The correlation between blood levels of ibuprofen and clinical analgesic response. Clin Pharmacol Ther. 1986 Jul;40(1):1-7. http://www.ncbi.nlm.nih.gov/pubmed/3522030