Evaluating Meta-Analyses Flashcards

1
Q

Advantages of meta-analyses

A

Increased power
Clarify direction of literature

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2
Q

How to avoid publication bias?

A

One must systematically search for negative trials for inclusion

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3
Q

How to get around the problem of having different types of studies in a meta-analyses?

A

Clear inclusion criteria
Forest plots
Heterogeneity statistics

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4
Q

What happens if a study has missing data?

A

Cannot be included in a meta-analyses

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5
Q

When does one explore subgroup findings?

A

As a way to explain failure to find overall effect - these can be studied in further RCTs

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6
Q

Disadvantage of doing further analysis on subgroups

A

Potential for confounding and misleading findings

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7
Q

Why does subgroup analysis lead to potential for misleading findings?

A

Randomisation between treated and control groups does not extend to subgroups

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8
Q

Reason for sensitivity analysis

A

Process of selection, inclusion and aggregation of data may affect main findings of meta-analysis

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9
Q

What does sensitivity analysis do?

A

Explores the ways in which the main findings are changed by varying the approach to aggregation

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10
Q

What should good sensitivity analysis do?

A

Mode the effect of excluding various categories of studies
Examine how consistent results are across sub-groups

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11
Q

What happens if a meta-analysis does not have sensitivity analysis?

A

Reader has to make guesses about likely impact of selection, inclusion and aggregation of data on the conclusion of the study

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12
Q

Where will line of no difference be on a forest plot if final estimate is standardised mean of Cohens d?

A

Placed on 0

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13
Q

Where will the line of no difference be on a forest plot if point estimate is relative risk or ratio measure

A

1

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14
Q

How do we know if a study gives precise results form a forest plot?

A

Horizontal line across the square will be shorter

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15
Q

What does it mean if a studys line crosses the line of no effect on a forest plot?

A

Results are not statistically significant

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16
Q

Why does the diamond in forest plots have no line?

A

As pooled results have highest precision

17
Q

What does it mean if the diamond in forest plots does not cross line of no difference?

A

We can be confident that the results of meta-analysis are decisive to some extent (statistically)