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Systematic Reviews and Meta-Analysis, Advantages of SR and MTA - Coggle…
Systematic Reviews and Meta-Analysis
Types of Review articles
Traditional/Narrative
Broad overview or background of a topic (natural history or etiology)
Summarize results or findings from work of others (Informal and subjective methods that is subject to bias
Systematic Review
Clear, specific clinical question
Systematic and explicit pre-determined methods
Uses standardized protocol (reproducible w/ minimized selection bias)
May or may not include an MTA
Meta-analysis (MTA)
Statistically combining the results of at least 2 studies to produce a single estimate of an effect (trying to get aggregate study level data)
Do not have to be part of a systematic review
Essential to recognize how well this was actually done based on rigor of the studies going into the MTA/SR
Individual Patient Data (IPD)
Raw, individual data for each study (sometimes combined and re-analyzed for an MTA)
Want to confirm that aggregate data is consistent w/ IPD
Standardization of analyses across studies
How to critically appraise SR and MTA
Did authors address a clearly focused question? (PICO)
Did they pick right types of papers? (appropriate for clinical question)
Did include all important and relevant studies? (Details about search, strategy and databases used)
Failure to include all relevant studies could lead to an overestimate of the benefits of treatment
Reporting Bias
Publication bias
Assessing Reporting bias
Funnel Plots
Triangle scatterplot graphs that can be used to assess for reporting bias
Egger's test
Actual statistical test
Trials not included because studies with non-significant results are not published
Language bias
Trials not included because studies not in English
Citation bias
Trials w/ significant effects were cited more often and are more likely to be included
Time lag bias
Trial more likely to be included because the study addressed a "hot topic" or was rushed for publication
Did they assess the quality of the included studies? (methodological rigor)
If MTA - Was it reasonable to do so? (homogeneity vs. heterogeneity, display all results, explain variations)
Assessing for Heterogeneity
Chi-Square test & p-value
Higgins I^2 test
Provides percentage of variation between sample estimates that is due to hetreogeneity
Forest Plot
Always used for meta-analysis
Additional Analyses
Sensitivity analysis
Comparing the effects of the intervention in different groups of
studies
Should be specified "a priori"
Subgroup analysis
Focuses on a particular subgroup of
patients
(not trials) across all included studies
ie. male v. female, cancer v. non-cancer
Should be specified "a priori"
What were overall results?
How precise were the results?
Can we apply results locally?
Did they consider all important outcomes? (is there anything they could have included?)
Are the benefits woth the harms and costs?
Advantages of SR and MTA
Increase power and precision by combingin aggregate results
Reduce large amount of data into manageable amount
Significant overall treatment effect where individual studies found differing results