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Flashcards in Systematic reviews and meta analysis Deck (22):

What is a systematic review?

A review of a clearly formulated question that uses systematic and explicit methods to identify, select, and critically appraise relevant research, and to collect and analyse data from the studies that are included in the review.


What is a meta analysis?

The statistical techniques used in a systematic review


Why do we need systematic reviews?

Because data quantity has increased over time. We also need SRs to assess the quality of evidence


What are the main advantages of a systematic approach?

It is transparent process due to explicit methods in identifying and rejecting studies

Meta analysis increases power of study and enhance precision of estimates of treatment effects, accounts for sample size and uncertainties

They show which areas need further studies


What are steps involved in systematic review?

Stage 1: planning review
Stage 2: identification of research, selection of studies, study quality assessment
Stage 3: reporting dissemination


What are advantages of a meta analysis?

More subjects can be included- more precise estimate of effect and differences between published studies can be explored. You can also identify whether publication bias is occurring.


What are the limitations of meta analysis?

Publication bias, labour intensive, inconsistency of results, low study quality


How do you visually summarise results of meta analysis?

Forest plot


What is publication bias?

The greater likelihood of research with statistically significant results to be published in the peer-reviewed literature


How can you explore publication bias?

Funnel plots


Why might heterogeneity occur?

Due to differences in interventions, outcomes, study designs


How can heterogeneity be explored?

Galbraith (radial) plots


What are the limitations of systematic reviews?

If there are too few studies matching eligibility criteria, SR is not v. beneficial. If quality of studies is inadequate, findings of SR are compromised. Publication bias can distort findings.


What does the size of a box in a forest plot indicate?

Weight given to the overall study


What do the horizontal lines in a forest plot indicate?

95% confidence interval


What does the the diamond in a forest plot show?

The overall estimate. the centre of the diamond and dashed line shows the summary effect estimate and the width of the diamond refers to the confidence interval.


What does a symmetrical funnel plot indicate?

No publication bias


What should reporting a systematic review involve?

PICOS: populations, interventions, control, outcomes and study design


When is Tau squared test used?

In the estimate of between-study variance based on random effect model


When is the Chi squared test used?

Test of statistical significance for heterogeneity (lower power)


When is the I squared test used?

Measure or index of heterogeneity


What is the difference between a fixed effects and random effects model in a meta analysis?

A fixed effect meta-analysis assumes all studies are estimating the same (fixed) treatment effect, whereas a random effects meta-analysis allows for differences in the treatment effect from study to study.