2. Information about Health Care Is
Everywhere !!!
But how do you know if one health care
intervention works better than another ?
Or if it will do more harm than good?
2
4. There are more than 23,000 medical journals and if
you want to keep up to date, you have to read about
90 journals, in full, every day
Try to remember how you write your review
articles?
4
5. Narrative reviews
• Most people are highlighting what they like and
what fit their hypothesis
• There is no clearly specified methods of
identifying, selecting, and validating including
information
5
6. What is a Systematic review?
• Uses explicit preplanned scientific methods to
identify, select, appraise & summarizes similar
but separate studies
All reviews
SR
SR with
MA
6
7. Knowledge Translation: from Clinical
Research to Practice Decisions
Clinical trial Cochrane Professionals Application
Observational collaboration Societies of policy
Studies
Clinical
policy
(guidelines)
Evidence
synthesis
(SR)
Evidence-
based
healthcare
Knowledge translation 7
8. Who Is Using Systematic Reviews?
Decision Makers
• Individual doctors and researchers
• Patients and consumers
• Policy makers
8
9. Steps of a Systematic Reviews
Frame research question (PICO/PECO)
Develop protocol
Develop search strategy
Run search strategy in at least two databases
Retrieve and de-duplicate citations
Develop system for screening titles/abstracts and full-texts
Screen titles/abstracts
Retrieve and screen full-texts
Develop forms for assessing ‘risk of bias’ and extracting data
Conduct qualitative synthesis( combine the studies)
Conduct meta-analyses (if appropriate)
Write report of systematic review
Update systematic review
9
13. Major databases for RCTs and
observational studies:
MEDLINE/PubMED
(www.ncbi.nlm.nih.gov/sites/entrez?)
Cochrane Central Register of Controlled Trials
(CENTRAL)
EMBASE (www.embase.com)
SCOPUS
CTRI
CINAHL
PsychINFO
13
14. Clinical question:
For patients with choroidal neovascularization
associated with age related macular degeneration,
do intra vitreal injections of Lucentis when
compared with Avastin prevent vision loss?
14
15. To develop simple search
strategy!!!
Break into concepts
P Individuals with choroidal neovascularization associated
with age-related macular degeneration
I Lucentis
C Avastin
O Change in visual acuity or visual field
15
16. To develop simple search
strategy!!!
Boolean operators
AND, OR, NOT
16
A
N
D
CNV OR
Choroidal
neovascula
risation
Lucentis OR
Avastin
25. Reporting guidelines
• PRISMA
(Preferred Reporting Items for Systematic review and
Meta-Analysis)2009 flow diagram.lnk
• MOOSE (Meta-analysis of Observational Studies in
Epidemiology)
25
26. Data extraction
Author
Year
Study design
Population
Male / females
Sample size
Diagnostic test
Intervention
Outcomes etc.
26
27. Quality assessment:
1. New castle Ottawa scale NOS.pdf
( For observational studies)
2. Jadad scale (For RCTs)
27
28. Publication bias:
Publication bias is a term used when studies
with positive results have a higher likelihood of
being published
Publication bias can be linked to favorable or
unfavorable treatment of research findings due
to investigators, editors, industry, commercial
interests, or peer reviewers
A funnel plot–a scatter plot of component
studies
28
31. Heterogeneity
Any kind of variability among studies
Clinical heterogeneity
Patients, study settings , quality,intervention,outcome
• Statistical heterogeneity
Results of individual trials are not consistent with each
other
( p value for cochrane Q statistics < 0.10
I2 statistic > 50 % )
31
32. What is a Meta-Analysis?
Meta-analysis is an optional component of a
systematic review
“A statistical analysis which combines the results of
several independent studies considered by the
analyst to be ‘combinable”
32
33. When to do meta-analysis
• More than one study has estimated a treatment effect or
association
• The differences in the study characteristics are unlikely to
affect the treatment effect
• The treatment effect have been measured and reported in
similar ways
33
36. Interpretation of forest plot
Often, we have 6 columns in a forest plot.
Column 1: Studies IDs
Column 2 and column 3: Intervention group n/N and
Control group n/N
Column 4: Relative risk (fixed) 95% CI
Column 5: Weight (%)
Column 6: Relative risk (fixed) 95% CI
same as 4, just in numerical format.
36
37. Interpretation of forest plot
The p-value indicates the level of statistical
significance.
If the diamond shape does not touch the line of no
effect, the difference found between the two groups
was statistically significant.
In that case, the p-value is usually < 0.05.
37
Inevitably, studies brought together in a systematic review will differ. Any kind of variability among studies in a systematic review may be termed heterogeneity. It can be helpful to distinguish between different types of heterogeneity. Variability in the participants, interventions and outcomes studied may be described as clinical diversity (sometimes called clinical heterogeneity), and variability in study design and risk of bias may be described as methodological diversity (sometimes called methodological heterogeneity). Variability in the intervention effects being evaluated in the different studies is known as statistical heterogeneity, and is a consequence of clinical or methodological diversity, or both, among the studies. Statistical heterogeneity manifests itself in the observed intervention effects being more different from each other than one would expect due to random error (chance) alone. We will follow convention and refer to statistical heterogeneity simply as heterogeneity.