Evidence Hierachy

Question 1

What are the 7 levels of evidence.

Answer 1

Meta analysis
Systematic review
RCT
Cohort
Case controlled
Case series/case report
Expert opinion

Question 2

what is the evidence hierarchy?

Answer 2

Ranks different research or evaluation study designs based on rigour of research methods.

gives researchers a crude method to identify how much confidence should be invested in a study based upon the design (less prone to bias)

Where there is a lack of robust research evidence it is important to use a range of evidence types to draw conclusions

Question 3

define meta analysis and systematic review

Answer 3

assess the consistency of results and risk of bias between all studies investigating a topic and demonstrate the overall effect of an intervention or exposure amongst these trials.

Question 4

define randomised control trials

Answer 4

designed to minimize confounding bias and test causal relationships between groups regarding the effect of an intervention on an outcome.

Have robust research **methodology **

key feature = participants are randomly assigned either ‘treatment’ or a ‘control’ group

if the participants in ‘treatment’ have better outcomes than those
in the ‘control’ , it is likely that the program is effective

Question 5

define cohort studies and case-controlled studies

SIC bias

Answer 5

have a comparison or control group but no random assignment.

retrospective and cohort studies prone to various biases (confounding, selective). *Prospective *cohort studies are considered more reliable and less prone to information bias

case-controlled: a type of observational study, the outcome has already occurred, and the researchers are attempting to discover if an association between the outcome and an exposure/risk factor exists. prone to selection, information and confounding bias

Question 6

Case series and case reports

Answer 6

cohort studies that lack a control group.
Lack of a comparison group hampers the ability to obtain an association between the variable being investigated and the effects

Question 7

what is selection bias

Answer 7

he systematic differences that exist between participants limit the ability to equally compare the groups and arrive at unbiased conclusions.
sampling, loss of follow up, recall, exclusion

Question 8

what is confounding bias

Answer 8

When one variable creates the illusion of an association between a different variable and an outcome

issue in observational clinical research because confounding bias can lead to spurious conclusions.

Question 9

What is a meta analysis

Answer 9

Statistical analysis of several studies