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Systematic review and Meta-analysis
PART 2
Ahmed Said Negida
Fourth year (MBBCH) student at Zagazig University
Leader of M...
Learning objectives
 Quality assessment (ROB assessment tool).
 Baseline characteristics tables.
 Figures of (PRISMA fl...
Quality assessment (ROB assessment tool).
 Cochrane ROB tool is used to assess the quality randomized controlled trials.
...
Components of Cochrane ROB tool
1. Sequence generation
2. Allocation concealment
3. Blinding
4. Incomplete outcome data
5....
1. Sequence generation
Low RISK HIGH RISK
1- Computer generated
2- Randomization tables
3- Block randomization
4- Minimiza...
2. Allocation concealment
Low RISK HIGH RISK
1- Central Allocation
2- Opaque envelop
3- Sealed envelop
4- Allocators were ...
3. Blinding
Low RISK HIGH RISK
1- Patients and study personnel
were blinded to ttt groups.
2- They were not blinded but th...
4. Incomplete outcome data
Low RISK HIGH RISK
1- No missing outcome data
2- Missing are not related to true
outcome. “surv...
5. Selective outcome reporting
Low RISK HIGH RISK
1- All pre-specified outcomes in
the protocol were reported.
2- Protocol...
6. Other sources of bias
Low RISK HIGH RISK
The study is free from other
sources of bias.
1- Stopped early due to some
dat...
How to generate ROB graphs in RevMan
(1) Add eligible studies from
references to included studies.
(2) From “tables”,
open
“characteristics of
included studies”.
(3) Select
author
judgment for
each of the
ROB domains.
(4) Add Figure.
(5) Choose:-
Risk of Bias Graph
Then, Risk of Bias
Summary.
Baseline characteristics tables
 Importance of baseline characteristics
 Describe population in the starting point.
 Ef...
1. Continuous variables
e.g. Age, Weight, Height, BMI, UPDRS
 Mean (SD)
 Median (IQR)
2. Categorical variables
e.g. Gender, grade,…
 Frequency (Percentage)
REFERENCE:
Mingrone, Geltrude, et al.
"Bariatric surgery versus
conventional medical therapy
for type 2 diabetes." New
Eng...
Reference:
Venturelli, Massimo, Renato Scarsini, and
Federico Schena. "Six-month walking
program changes cognitive and ADL...
Reference
Klop, Karel WJ, et al. "Can right‐sided
hand‐assisted retroperitoneoscopic donor
nephrectomy be advocated above
...
 Identify the (most important & commonly reported) variables within
baseline characteristics table of included studies.
...
How to format the baseline characteristics table of a systematic review
GROUP 1 GROUP 2
GROUP 1
GROUP 2
GROUP 1
GROUP 2
V1...
EXAMPLE 1
EXAMPLE 2
PRISMA
checklist
TITLE Risk of bias across studies
ABSTRACT Additional analyses
Structured summary RESULTS
INTRODUCTION St...
Introduction to Meta-analysis
Meta-analysis is a statistical method for quantitative
evidence synthesis in which eligible ...
Introduction to Meta-analysis
 Advantages ??
 Disadvantages ??
 Idea of meta-analysis ??
Effect size
Mean difference (MD) X – Y
Standardized Mean Difference (SMD) (X – Y) / SD
Risk Ratio (RR) X / Y
Risk Differen...
Random effect model vs. Fixed effect model
 Study weights are more balanced under the random-effects
model than under the...
Interpretation of forest plots
The following forest plots shows the standardized mean difference of
hospital stay after Ho...
The following forest plots shows the standardized mean difference of
change in HBa1c in Gastric Bypass surgery versus Medi...
The following forest plots shows the standardized mean difference
of change in BMI in Gastric Bypass surgery versus Medica...
The following forest plots shows the standardized mean difference
of change in total UPDRS score in Coenzyme Q10 group vs....
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Systematic review and meta analaysis course - part 2

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This presentation is the second part from Ahmed Negida's course titled: Systematic review and Meta-analysis.

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Systematic review and meta analaysis course - part 2

  1. 1. Systematic review and Meta-analysis PART 2 Ahmed Said Negida Fourth year (MBBCH) student at Zagazig University Leader of Medical Research Group of Egypt (MRGE) Clinical Research Assistant at Egyptian Liver Research Institute and Hospital Head of scientific committee of the Student Research Unit, Zagazig University
  2. 2. Learning objectives  Quality assessment (ROB assessment tool).  Baseline characteristics tables.  Figures of (PRISMA flow diagram, ROB summary and ROB graph).  PRISMA checklist.  Introduction to Meta-analysis.
  3. 3. Quality assessment (ROB assessment tool).  Cochrane ROB tool is used to assess the quality randomized controlled trials.  For observational studies (use STROBE or NOS instead).  For non-randomized studies (Use ACROBAT NRSI tool).
  4. 4. Components of Cochrane ROB tool 1. Sequence generation 2. Allocation concealment 3. Blinding 4. Incomplete outcome data 5. Selective outcome reporting 6. Others HIGH risk LOW risk Unclear
  5. 5. 1. Sequence generation Low RISK HIGH RISK 1- Computer generated 2- Randomization tables 3- Block randomization 4- Minimization procedure 1- Quasi-random 2- Patient preference 3- clinician judgment 4- Day of visit 5- Patient ID 6- Day of birth
  6. 6. 2. Allocation concealment Low RISK HIGH RISK 1- Central Allocation 2- Opaque envelop 3- Sealed envelop 4- Allocators were blinded 5- Identical drug containers 1- Transparent envelop 2- Allocators were not blinded 3- Random sequence known in advance
  7. 7. 3. Blinding Low RISK HIGH RISK 1- Patients and study personnel were blinded to ttt groups. 2- They were not blinded but this is not likely to affect the outcome. 1- Open label study 2- No placebo group “observation group”.
  8. 8. 4. Incomplete outcome data Low RISK HIGH RISK 1- No missing outcome data 2- Missing are not related to true outcome. “survival outcome” 3- Missing outcome data balanced in numbers across intervention groups. 4- Missing data were handled by ITT. 1- missing data >5%-10% 2- Missing data were not handled with appropriate analysis.
  9. 9. 5. Selective outcome reporting Low RISK HIGH RISK 1- All pre-specified outcomes in the protocol were reported. 2- Protocol was not available but it is expected that all major outcomes are reported. 1- One or more of the pre- specified outcomes is not reported. “or reported on different scales” 2- One or more of the reported outcomes was not planned.
  10. 10. 6. Other sources of bias Low RISK HIGH RISK The study is free from other sources of bias. 1- Stopped early due to some data-dependent process. 2- Had extreme baseline imbalance. 3- Had some other problem (….)
  11. 11. How to generate ROB graphs in RevMan (1) Add eligible studies from references to included studies.
  12. 12. (2) From “tables”, open “characteristics of included studies”.
  13. 13. (3) Select author judgment for each of the ROB domains.
  14. 14. (4) Add Figure. (5) Choose:- Risk of Bias Graph Then, Risk of Bias Summary.
  15. 15. Baseline characteristics tables  Importance of baseline characteristics  Describe population in the starting point.  Effect size (SMD) = (End point/SD – Starting point/SD)  To detect between group differences.  How baseline characteristics are presented Usually, they are the first table in the “Results” section.  Type of variables presented 1. Continuous 2. Categorical
  16. 16. 1. Continuous variables e.g. Age, Weight, Height, BMI, UPDRS  Mean (SD)  Median (IQR)
  17. 17. 2. Categorical variables e.g. Gender, grade,…  Frequency (Percentage)
  18. 18. REFERENCE: Mingrone, Geltrude, et al. "Bariatric surgery versus conventional medical therapy for type 2 diabetes." New England Journal of Medicine 366.17 (2012): 1577-1585.
  19. 19. Reference: Venturelli, Massimo, Renato Scarsini, and Federico Schena. "Six-month walking program changes cognitive and ADL performance in patients with Alzheimer." American journal of Alzheimer's disease and other dementias 26.5 (2011): 381-388.
  20. 20. Reference Klop, Karel WJ, et al. "Can right‐sided hand‐assisted retroperitoneoscopic donor nephrectomy be advocated above standard laparoscopic donor nephrectomy: a randomized pilot study." Transplant International 27.2 (2014): 162-169.
  21. 21.  Identify the (most important & commonly reported) variables within baseline characteristics table of included studies.  Present each study as (one, two, or more…) rows.  Each row represents a group within a study. For example: If you have a four arm trial, this will be presented in four rows.  Present variables as columns. How to format the baseline characteristics table of a systematic review
  22. 22. How to format the baseline characteristics table of a systematic review GROUP 1 GROUP 2 GROUP 1 GROUP 2 GROUP 1 GROUP 2 V1 V2 V3 V1 V2 V3 Table of an individual study Table of a systematic review
  23. 23. EXAMPLE 1
  24. 24. EXAMPLE 2
  25. 25. PRISMA checklist TITLE Risk of bias across studies ABSTRACT Additional analyses Structured summary RESULTS INTRODUCTION Study selection Rationale Study characteristics Objectives Risk of bias within studies METHODS Results of individual studies Protocol and registration Synthesis of results Eligibility criteria Risk of bias across studies Information sources Additional analysis Search DISCUSSION Study selection Summary of evidence Data collection process Limitations Data items Conclusions Risk of bias in individual studies FUNDING Summary measures Risk of bias across studies Synthesis of results
  26. 26. Introduction to Meta-analysis Meta-analysis is a statistical method for quantitative evidence synthesis in which eligible studies are pooled together in the meta-analysis model to give an overall effect size with a greater power.
  27. 27. Introduction to Meta-analysis  Advantages ??  Disadvantages ??  Idea of meta-analysis ??
  28. 28. Effect size Mean difference (MD) X – Y Standardized Mean Difference (SMD) (X – Y) / SD Risk Ratio (RR) X / Y Risk Difference X – Y Odds Ratio X / Y from a case control study  For continuous outcomes  For categorical outcomes  Others: e.g. Hazard Ratio (HR)
  29. 29. Random effect model vs. Fixed effect model  Study weights are more balanced under the random-effects model than under the fixed-effect model. Large studies are assigned less relative weight and small studies are assigned more relative weight as compared with the fixed-effect model.  The standard error of the summary effect and (it follows) the confidence intervals for the summary effect are wider under the random-effects model than under the fixed-effect model.
  30. 30. Interpretation of forest plots The following forest plots shows the standardized mean difference of hospital stay after Holmium Laser Enucleation of Prostate in comparison to Transurethral resection of prostate:
  31. 31. The following forest plots shows the standardized mean difference of change in HBa1c in Gastric Bypass surgery versus Medical Therapy:
  32. 32. The following forest plots shows the standardized mean difference of change in BMI in Gastric Bypass surgery versus Medical Therapy:
  33. 33. The following forest plots shows the standardized mean difference of change in total UPDRS score in Coenzyme Q10 group vs. placebo group: NB: pooled studies are heterogeneous

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