Levels of Evidence

Question 1

Characteristics of a systematic review and meta-analysis

Answer 1

Analysis of multiple studies (usually RCTs)

Appraise the

• quality of studies
• ways bias and confounders have been minimised

Often use statistical techniques

Question 2

Characteristics of an RCT

Answer 2

Subjects are randomly assigned to a treatment or control group

Random allocation and blinding reduce bias

Question 3

Characteristics of cohort studies

Answer 3

Prospective study

Individuals with exposure of interest compared over time with individuals without the exposure

Question 4

Characteristics of case control studies

Answer 4

Retrospective study

Individuals with a condition of interest are retrospectively compared to a group of people without the condition

Aim to determine exposures

Question 5

Characteristics of animal and cell studies

Answer 5

Pre-clinical research used to predict the effects of an intervention in humans

Question 6

What questions would you need to ask to understand the content of a paper

Answer 6

What is the

• research question
• hypothesis
• population
• intervention
• comparator
• outcome

Are the methods appropriate

Have sources of bias been addressed

What are the confounders

Are the statistical analyses correct?

Does the data justify the conclusion?
Are the conclusions inline with the research question and methodology?

Question 7

What are the questions you want to ask when assessing an RCT

Answer 7

Research question?
Is it justified?

Blinding?
Random allocation?
-was everyone accounted for in final analysis

Experimental conditions?

What outcomes were measured

Limitations?

Question 8

What are the questions you want to ask when assessing an animal/cell study

Answer 8

Hypothesis?
Is it justified?

Experimental conditions
-how were they selected and how do they compare to human conditions

No of subjects/repeats per group

What was measured

How appropriate is the animal model or cell type used?

Limitations?

Question 9

Good practice for writing

-where should you put the hypothesis/research question

Answer 9

Stated in the introduction/background

A summary of the study design may be found in the last paragraph of the introduction

Question 10

Good practice of writing

-where should you put the primary outcomes

Answer 10

Usually stated in the abstract and methods