Development and the Role of Meta-analysis on the Topic of Inflammation

Donald S. Likosky, Ph.D.

Disclosures• No relevant disclosures

Goals for Talk• What is a Meta-Analysis?

• Why is Meta-Analysis Important?

• How to Interpret a Meta-Analysis

• Relevance to Inflammation

Goals for Talk• What is a Meta-Analysis?

• Why is Meta-Analysis Important?

• How to Interpret a Meta-Analysis

• Relevance to Inflammation

What is a Meta Analysis• A systematic review of a topic, based

on discrete question

• Seeks to address the magnitude and precision of an intervention

• Unit of analysis is a study (usually restricted to published studies)

• Meta analysis is not just a big randomized trial

What is a Meta Analysis• Primary measure is the magnitude of

effect across studies (not patients)

• We don’t average values

• Weight each study by its sample size– 1 / (standard error)2

• Reflects findings across published studies

• There may be reasonable concerns about publication bias

• Assumes studies focused on same patients & study populations (requires in/exclusion criteria)

• Assumes authors have provided the required data (sometimes need to correspond with authors)

Goals for Talk• What is a Meta-Analysis?

• Why is Meta-Analysis Important?

• How to Interpret a Meta-Analysis

• Relevance to Inflammation

•How do you possible compare these studies?•Should they get equal weighting?•How much variance might there be in their estimates?

Number of Patients in Each of 10 Studies

Goals for Talk• What is a Meta-Analysis?

• Why is Meta-Analysis Important?

• How to Interpret a Meta-Analysis

• Relevance to Inflammation

What is a Meta Analysis• Primary measure is the magnitude of

effect

• We don’t average values

• Weight each study by its sample size– 1 / (standard error)2

Primary Measure• I2, “I-squared”

• Measure of degree to which studies are comparable

• Want homogenous studies (I2 <25%)

Study ID

# in StudyMean (SD) in Intervention Arm

# in StudyMean (SD) in Control Arm

Effect Measure“Weighted Mean Difference”

Weights per Study

Overall EffectDegree to which StudiesAre SimilarOverall Significance Line of Difference

Goals for Talk• What is a Meta-Analysis?

• Why is Meta-Analysis Important?

• How to Interpret a Meta-Analysis

• Relevance to Inflammation

Of 8 studies on C3a

Time Points # Studies Contributing Data

Pre-operative 8

5-30min on CPB 3

45-60min on CPB 5

end of CPB 5

5-15 after Protamine 4

POD 1 2

Pre-operative

5-30min on CPB

POD 1

Conclusions • Meta-Analyses have a role in evaluating body of

literature

• They require thoughtful care in their design and interpretation

• May have a useful role in – Evaluating effects of coated circuits on the

inflammatory response,– In improving the design and conduct of future

studies

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