| 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 |
[24] Zinc and castor oil ointment: Health Quality Ontario. Pressure ulcer prevention: an evidence-based analysis. Ont Health Technol Assess Ser. 2009;9(2):1-104. https://www.ncbi.nlm.nih.gov/pubmed/23074524
Zinc and castor oil ointment: Langemo D, Haesler E, Naylor W, Tippett A, Young T. Evidence-based guidelines for pressure ulcer management at the end of life. Int J Palliat Nurs. 2015 May;21(5):225-32. https://www.ncbi.nlm.nih.gov/pubmed/26107544