Evidence-Based Research - Nursing - Evidence-Based Practice - RichmondCC Library at Richmond Community College

Types of Evidence

Level One: Systematic Reviews or Meta-analysis	A systematic review summarizes the results of available carefully designed healthcare studies (controlled trials) and provides a high level of evidence on the effectiveness of healthcare interventions. Judgments may be made about the evidence and inform recommendations for healthcare.
Level Two: Randomized Controlled Trials	A study in which people are allocated at random (by chance alone) to receive one of several clinical interventions. One of these interventions is the standard of comparison or control.The control may be a standard practice, a placebo ("sugar pill"), or no intervention at all.
Level Three: Cohort Study	A type of medical research used to investigate the causes of disease, establishing links between risk factors and health outcomes. Cohort Studies are usually forward-looking - that is, they are "prospective" studies planned in advance and carried out over a future period of time.
Level Four: Case-Control Study	A study that compares patients who have a disease or outcome of interest (cases) with patients who do not have the disease or outcome (controls), and looks back retrospectively to compare how frequently the exposure to a risk factor is present in each group to determine the relationship between the risk factor and the disease.
Level Five: Case Reports, Case Series	Case reports are considered the lowest level of evidence, but they are also the first line of evidence, because they are where new issues and ideas emerge. This is why they are towards the base of our pyramid. A good case report will be clear about the importance of the observation being reported.
Level Six: Editorials, Expert Opinion	Recommendations from persons with established expertise in a specific clinical area usually based on clinical experience. Not considered a research method because critical inquiry is lacking.

Questions and Evidence

QUESTION	PRIMARY RESEARCH	SYNTHESIZED RESEARCH (Secondary Sources)	DATABASE
Therapy What is the best treatment or intervention?	Randomized Controlled Trials Controlled Trials	Systematic Reviews	PubMed (P,S) MedlinePlus (S) ClinicalTrials.gov (P) CochraneLibrary(S) ProQuest Nursing (S) CINAHL (S)
Prevention How Can I prevent this problem?	Randomized Controlled Trials Controlled Trials	Systematic Reviews	PubMed (P,S) MedlinePlus (S) ClinicalTrials.gov (P) CochraneLibrary(S) ProQuest Nursing (S) CINAHL (S)
Diagnosis/Assessment What is the best way to asses or best diagnostic test for this patient?	Instrument Development Research		PubMed (P,S) ClinicalTrials.gov (P)
Causation What causes this problem?	Cohort Study Case-Control Study Descriptive/Qualitative Study	Systematic Reviews	PubMed (P,S) MedlinePlus (S) ClinicalTrials.gov (P) CochraneLibrary(S) ProQuest Nursing (S) CINAHL (S)
Prognosis What are the long term effects of this problem?	Cohort Study Descriptive Study	Systematic Reviews	PubMed (P,S) MedlinePlus (S) ClinicalTrials.gov (P) CochraneLibrary(S) ProQuest Nursing (S) CINAHL (S)
Meaning What is the meaning of this experience for patients?	Qualitative Study	Systematic Reviews	PubMed (P,S) MedlinePlus (S) ClinicalTrials.gov (P) CochraneLibrary(S) ProQuest Nursing (S) CINAHL (S)