| 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 |
[12] Proton pump inhibitor, oral (therapeutic class): National Department of Health: Affordable Medicines, EDP-Adult Hospital level. Medicine Review: PPIs, therapeutic class review, April, 2018. http://www.health.gov.za/
Proton pump inhibitor, oral (therapeutic class): McDonagh MS, Carson S, Thakurta S. Drug Class Review: Proton Pump Inhibitors: Final Report Update 5 [Internet]. Portland (OR): Oregon Health & Science University; 2009 May. Available from http://www.ncbi.nlm.nih.gov/books/NBK47260/
Proton pump inhibitor, oral (therapeutic class): National Institute for Health and Care Excellence: Clinical Guidelines: Gastro-oesophageal reflux disease and dyspepsia in adults: investigation and management. https://www.nice.org.uk/guidance/cg184