This PowerPoint presentation was created and published as part of the assignments on Digitial Education.

1. Introduction to
Systematic Review
and Meta-analysis
Image taken from https://communications-marketing.ed.ac.uk/about-us

2. Introduction
• What is the difference between a systematic
review and meta-analysis?
• Systematic review – A review of
methods and results from all individual
studies which focus on a particular
research question and conform to a set
criteria
• Meta-analysis – Involves use of special
statistical methods to obtain overall
single estimate, by combining the results
of all individual studies

3. Step 1: Research Question
• P – Patient, problem or population
• I – Intervention
• C – Comparison, control or comparator
• O – Outcome(s) (e.g. pain, fatigue, nausea, infections, death)

4. Step 2: Data Resources
Data Resources
Published
Literature
• Core
• Specific
Grey Literature

5. Step 2: Data Resources – Core
Core Resources
Cochrane Library
 Cochrane Reviews
 Registry of Clinical Trials
Intervention & diagnostic reviews
Critically appraised and re-structured abstracts
Global registry of clinical trials
Medline
 Ebsco, Ovid or PubMed
Major medical literature database, produced by US National
Library of Medicine.
Embase Strong on European studies, pharmacological literature,
conference abstracts. Both Medline and Embase are
complementary and essential for searching core clinical topics.
Web of Knowledge Large multidisciplinary databases with citation searching.
Biomedical sciences, social science, conferences.
SCOPUS Large multidisciplinary database with citation searching.

6. Step 2: Data Resources – Specific
Subject Specific Resources
CINAHL Plus with Full Text Nursing and allied health
PsycInfo Psychology & psychiatry
EMERALD Management, health services, social sciences
ERIC Education
Global Health Public health, international health, grey literature
Health Business Elite Healthcare administration and management
PEDro Physiotherapy
TOXLINE Effects of drugs and chemicals
Westlaw Irish legal materials, including statutes and case law

7. Step 2: Data Resources – Grey Literature
Grey Literature sources
 NLM (National Library of Medicine, US) - http://www.ncbi.nlm.nih.gov
 National Information Center on Health Services Research and Health Care Technology (NICHSR) http://www.nlm.nih.gov/nichsr/db.html
 Health Services & Sciences Research Resources (HSRR) https://hsrr.nlm.nih.gov/
 US National Institutes of Health Icite Index to Preprintshttps://icite.od.nih.gov/
 Indexes the main biomedical and social science preprint datbasess: arXiv, bioRxiv, ChemRxiv, medRxiv, Research Square, and SSRN.
Institutional repositories: scholarly collections from academic and professional organisations
 OpenDOAR: Directory of Repositories http://www.opendoar.org/
 Bielefeld Base: European research resources http://www.base-search.net/Search/Advanced
 Lenus: HSE Ireland health documentation http://www.lenus.ie/hse/
 RCSI: research repository https://repository.rcsi.com/
Theses
 EThOS http://ethos.bl.uk/ UK theses.
 DART-Europe http://www.dart-europe.eu/ European theses.
 Networked Digital Library of Theses and Dissertations http://search.ndltd.org/
Clinical Trials
 Cochrane Central Registry of Clinical Trials (access via library website)
 ClinicalTrials.gov https://clinicaltrials.gov/
 National Institutes of Health, US ISRCTN Registry http://www.isrctn.com/ global registry of trials
 WHO International Clinical Trials Registry Platform (ICTRP) http://www.who.int/ictrp/en/

8. Step 3: Data Extraction
Jacknunn, CC BY-SA 4.0, via Wikimedia Commoms
• Search strategy
• In PubMed for instance, PubMed
saves the search strategy as one
long string : Search (deep vein
thrombosis) AND (aspirin) AND
(travel OR aircraft OR airplane)
• MESH (Medical Subject Headings)
• Boolean Operators—AND, OR,
and NOT

9. Step 4: Assess the Data Eligibility
• Ideally two independent investigators
• Any disagreement is resolved by a 3rd reviewer
• PRISMA flow diagram
• Templates are available - http://www.prisma-
statement.org/PRISMAStatement/FlowDiagram.aspx
• Flow diagrams can also be generated using a Shiny App
available at
https://www.eshackathon.org/software/PRISMA2020.html

10. Step 5: Combine and Analysis Data
• Qualitative assessment
• JADAD Score for RCT
• Newcastle-Ottawa Scale
for non-RCT
• Cochrane bias assessment
tool
• Publication bias
• Funnel plot
• Quantitative assessment
• Forest plot

11. Step 5: Combine and Analysis Data
• Forest plot
• Funnel plot

12. Forest plot
James Grellier, CC BY-SA 3.0, via Wikimedia Commons
The Vertical represents the
‘Line of no effect’
The horizontal line across each box represents the
95% confidence interval. Shorter line are more
precise. If the CI includes 1, the effect is not
significant
The diamond shape represents the pooled outcome
of all the studies. The width of the diamond shape
corresponds to the confidence interval of the result
The square box
indicates the
size of the study

13. Funnel plot
• The funnel plot is a test for publication bias.
• If there is publication bias, there will be asymmetry at the wide
part of the funnel plot end due to the absence of small negative
studies
• In this case trials missing from the bottom right-hand corner
Figure taken from Mytton, O.T., et al., Systematic review and meta-analysis of the effect of increased
vegetable and fruit consumption on body weight and energy intake. BMC Public Health, 2014. 14(1): p.
886.

14. Registration and Guidelines
• Register with International prospective register of systematic reviews
• PROSPERO - https://www.crd.york.ac.uk/PROSPERO/
• Follow guidelines and checklists
• Preferred Reporting Items for Systematic Reviews and Meta-Analyses
(PRISMA) - http://prisma-statement.org/
• Meta-analysis of Observational Studies in Epidemiology (MOOSE)

15. References
• https://s4be.cochrane.org/blog/2016/07/11/tutorial-read-forest-plot/
• Gosall, N.K. and G.S. Gosall, The Doctor's Guide to Critical Appraisal. 2012: PasTest.
• Harris, M. and G. Taylor, Medical Statistics Made Easy. 2003: CRC Press.
• Mytton, O.T., et al., Systematic review and meta-analysis of the effect of increased
vegetable and fruit consumption on body weight and energy intake. BMC Public
Health, 2014. 14(1): p. 886.

16. Acknowledgment
• Slide 2 was shared by Dr. Rachna Rohilla (PGIMER Chandigarh)