Quantitative Synthesis IInteractive Quiz

Prepared for:

The Agency for Healthcare Research and Quality (AHRQ)

Training Modules for Systematic Reviews Methods Guide

www.ahrq.gov

For a meta-analysis of binary data, which of the following metrics is likely to be more statistically heterogeneous?

A.The odds ratio

B.The risk difference

Binary Data

Which of the choices listed below is not a reason to carry out a meta-analysis?

A.Explore heterogeneity of results across studies

B.Reduce uncertainty in the estimate of treatment effect

C.Correct errors in previous publications

Reasons for a Meta-analysis

What is the key difference between the fixed effect model and the random effects model?

A.The spelling

B.The random effects model will always give a wider confidence interval

C.The fixed effect model considers only within-study variations

Fixed Effects ModelVersus Random Effects Model

This conclusion is based on a significant association among “non-Chinese,” versus a nonsignificant association among “Chinese.” Do you agree with the conclusion?

A.Yes, I agree

B.No, I do not agree

Assessing Study Conclusions

Sergentanis TN, Economopoulos KP. Breast Cancer Res Treat 2010;12:195-202.

OR for GSTT1 null copy carriers (95%

CI)

Non-Chinese 1.13 (1.04, 1.22)

Chinese 1.06 (0.88, 1.29)

This is part of a table from a meta-analysis of genetic factors that concludes: “polymorphisms of both GSTT1 and GSTP1 genes seem [to be] associated with elevated breast cancer risk in a race-specific manner.”

CI = confidence interval; OR = odds ratio

Do you agree or disagree with their choice?

A.Yes

B.No

Assessing Study Methods

CI = confidence intervalF = fixed effects modelOR = odds ratio

As described in the methods section of a paper, the authors opted to use random or fixed effects models according to whether a heterogeneity test was significant.

Data on GSTP1

Sergentanis TN, Economopoulos KP. Breast Cancer Res Treat 2010;12:195-202.

It is important to critically appraise the methodological quality and reporting of information of studies included in meta-analyses.

In most meta-analyses, treatment effects across studies are more likely to be heterogeneous in the risk difference metric when compared with the risk ratio or the odds ratio.

The fixed effect model considers only the within-study variation, whereas the random effects model incorporates both within-study variation and between-study variations.

Summary

This quiz was prepared by Joseph Lau, M.D., and Thomas Trikalinos, M.D., Ph.D., members of the Tufts Medical Center Evidence-based Practice Center.

The information in this module is based on Chapter 9 in Version 1.0 of the Methods Guide for Comparative Effectiveness Reviews (available at: http://www.effectivehealthcare.ahrq.gov/repFiles/2007_10DraftMethodsGuide.pdf).

Authors