Reviewing The Evidence

Question 0

Explain the purposes of systematic reviews

Answer 0

Allows for quantitative comparison between primary studies

Question 1

Define a systematic review

Answer 1

A compilation of primary studies, usually randomised control trials (e.g. Cochrane library)
Studies narrowed down by relevance and credibility
Studies used should be transparent, explicit, reproducible

Question 2

Explain how to interpret a ‘Forest Plot’

Answer 2

Odds ratios - square
95% CI - line (increased CI = more people involved)
Pooled value - diamond
Size of squares represents weight given to study
Statistically significant if square overlaps line

Question 3

Explain how to interpret a ‘Funnel Plot’

Answer 3

Determines publication bias - systematic review should use published and unpublished trials
Should be an even distribution of trials
Small trials towards bottoms, large trials at top
Larger studies may be closer to true value

Question 4

List common difficulties in systematic reviews

Answer 4

Failing to exclude poor quality trails (subjected to bias)
Inappropriate combining of results (measuring different things)
Only including trials for particular situations
Failing to include all relevant trials (publication bias)

Question 5

List some advantages of systematic reviews

Answer 5

Can reduce bias and exclusion of poor quality studies
Meta-analysis provides overall value for studies
Reduce time between research breakthrough and clinical implementation
Large amounts of information can be assimilated quickly by healthcare professionals
Evidence based medicine

Question 6

Explain the meta-analysis models

Answer 6

Homogeneity - studies are identical
Heterogeneity - studies are varied
Fixed effects model - assumes the studies are homogenous and any variation between data comes from within study variation
Random effects model - assumes the studies are heterogenous and variation between data comes from within study variation and between study variation