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Quantitative Synthesis I Quiz

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Quantitative Synthesis I Quiz. Prepared for: The Agency for Healthcare Research and Quality (AHRQ) Training Modules for Systematic Reviews Methods Guide www.ahrq.gov
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Quantitative Synthesis I Quiz

Binary Data. 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.
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Binary Data

Reasons for a Meta-analysis. 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.
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Reasons for a Meta-analysis

Fixed Effects Model Versus Random Effects Model. 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.
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Fixed Effects Model Versus Random Effects Model

This slide presents part of a table from a meta-analysis of genetic factors that concludes that “polymorphisms of both GSTT1 and GSTP1 genes seem associated with elevated breast cancer risk in a race-specific manner.”The table consists of two columns, a header row and two data rows. Column one is used to label the rows. Column two is labeled “OR for GSTT1 null copy carriers 95% CI)”. Row one is labeled “Non-Chinese.” Column two contains the data “1.13 (1.04, 1.22).” Row two is labeled “Chinese.” Column two contains the data “1.06 (0.88, 1.29).” 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.
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Assessing Study Conclusions

Assessing Study Methods. 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. This slide also contains a table of two columns. To the right of the table are the notes “Data on GSTP1; F = fixed effects model”. The column on the left is labeled Race and is used to label the rows, which contain data from subgroups. The column on the right is labeled “Recessive model (GG vs. AA and AG).” It is divided into two columns which are labeled “OR (95% CI)” and “Test for heterogeneity.” Row one is labeled “Overall (n = 30).” In column two, OR and CI are 0.992 (0826-1.192) and heterogeneity is P < 0.001. Row two is labeled” Non-Chinese (n =25).” OR and CI are 0.979 (0.795-1.204) P < 0.001. Row three is labeled “Chinese (n=5).” OR and CI are 1.273 (superscript F) (1.006-1.610) P = 0.323. Do you agree or disagree with their choice? A. Yes. B. No.
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Assessing Study Methods

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.
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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).
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