Systemic Reviews and Meta-Analyses (Statistics)

Question 1

What is a systematic review?

Answer 1

A balanced and impartial summary of existing research, enabling decisions of efficacy

Question 2

What is a meta-analysis?

Answer 2

A systematic review with a quantitative estimate of effectiveness, safety by combining results of independent studies.

Advantages

-Refinement, reduction

-Increases precision

-Efficiency

-Generalisability

Disadvantages

-Publication bias - publications with a large treatment effect tend to get published fastest

Question 3

Outlining stages involved in meta-analysis

Answer 3

1. Frame the question, population, intervention, control, outcome
2. Quality of evidence? Unbiased. Typically include RCTs, randomisation and double blinding desirable
3. Summarise the evidence - often using forest plots (1 forest plot = specific to one outcome). Size of dot = sample size
4. Interpret findings

Heterogeneity- if there is heterogeneity consider looking at subgroups

Homogeneity - more conclusive

Question 4

Statistical tests in meta analysis

Answer 4

I^2 - describes the percentage of variation due to heterogeneity rather than chance. Less than 50 - homogenous

Z test - with a P value indicates the level of statistical significance. If diamond shape does not touch the line of no effect, difference between the two groups is statistically significant