Registered Nurses' Association of Ontario

Levels of Evidence

Type Therapy/Prevention/Etiology/Harm Prognosis
Ia Evidence obtained from systematic review and meta-analysis of randomized controlled trials. Evidence obtained from systematic review of inception of cohort studies
Ib Evidence obtained from at least one well-designed randomized control trial. Evidence obtained from at least one well-designed inception cohort study with follow-up.
IIa Evidence obtained from at least one well-designed controlled study without randomization. Evidence obtained from at least one well-designed retrospective cohort study or follow-up of untreated control patients in a randomized controlled trial.
III Evidence obtained from at least one well-designed nonexperimental quantitative study (i.e. comparative or correlational) or qualitative study. Evidence obtained from at least one well-designed non-experimental quantitative study (i.e. case-series, case-control studies, cohort studies and historically controlled studies).
IV Evidence obtained from expert committee reports or opinions, and/or clinical experiences of respected authorities. Evidence obtained from expert committee reports or opinions, and/or clinical experiences of respected authorities.
IV* Evidence obtained from other clinical practice guidelines. Evidence obtained from other clinical practice guidelines.

 

Clinical Management
End-of-Life Care During the Last Days and Hours
Practice Recommendations