1. Dr. Maryam Tajvar Department of Health Management and Economics
META ANALYSIS
Dr. Maryam Tajvar
Department of Health Management and Economics

3. How do a systematic review?

4. Data synthesis
Descriptively
Mathematically (Meta-analysis)

5. What is a meta-analysis?
"the statistical analysis of the data from a collection of studies in order to synthesise the results".
The quantitative synthesis of findings from separate, but related studies ... usually RCTs.
Cook, D. J., D. L. Sackett, et al. (1995). “Methodologic guidelines for systematic reviews of randomized control trials in health care from the Potsdam Consultation on Meta-Analysis.” J Clin Epidemiol 48(1):

6. Purposes of meta-analysis
Obtain overall summary estimate to improve precision
Test whether an “intervention” is effective with increase power
Assess whether results of different studies are heterogeneous
Greater objectivity, precision and applicability by including all available evidence.

8. Principles of meta-analysis
Produce a “forest plot”
Investigate heterogeneity between studies
Pool results

9. “forest plot”

10. Investigating heterogeneity: Chi-squared test of heterogeneity: when statistically significant heterogeneity, may not be appropriate to pool data and do meta analysis - So when we see heterogeneity, Don’t meta-analyse!!! You may explore the causes of the heterogeneity through sub-group analysis

15. Calculating summary statistics
Systematic review software , e.g. Review Manager (RevMan) , will calculate pooled results for you.
STATA has very good MA commands, but some of them have to be installed separately

16. Guidelines on how to write reviews & meta-analyses:
–QUORUM statement*
For meta-analysis of RCTs
–MOOSE guidelines**
For meta-analysis of observational studies
*Moher et al. The Lancet 1999;354:
**Stroup et al. JAMA 2000;283:

17. Useful links Cochrane Collaboration -www.cochrane.org
The York Centre for Reviews and Dissemination -
School of Health and Related Research, Sheffield -
Especially for non-RCTs –Campbell Collaboration -