Modern Methods of Clinical Investigation (1990) / Chapter Skim
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8. Meta-Analysis: A Quantitative Approach to Research Integration
8. Meta-Analysis: A Quantitative Approach to Research Integration
Pages 88-100
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From page 88... ...
Scientific research is founded on integration and replication of results; with the possible exception of a new discovery, a single study rarely makes a dramatic contribution to the advancement of knowledge (5~. In this article I summarize the constraints on reviewers of the medical literature and review alternative methods for synthesizing scientific studies.
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From page 89... ...
Variable data quality is probably the most critical limitation for the reviewer. The effect of data quality was seen in a study of quality of life outcomes following coronary bypass graft surgery, when investigators found the estimates of benefit to be 15 percent less in randomized controlled trials than in trials using matching (12~.
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From page 90... ...
, although in one large study of psychotherapy, the effect was found to increase with increasing rigor (111. In quantitative reviews, statistical methods, including stratified analyses and multivariate methods, can be used to measure the impact on the results of varying quality in studies (8,13,141.
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From page 91... ...
Third, references in available studies identify further sources. The retrieval from academic, private, and government researchers of unreferenced reports, the so-called fugitive literature, as well as unpublished data, further minimizes selective reporting and publication biases.
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From page 92... ...
The independent variable was defined as the clinical application of all forms of electronic fetal monitoring to both high- and low-risk pregnant women; the outcomes measured were various measures of maternal and fetal morbidity and mortality, as well as the occurrence of cesarean delivery. Cost issues were also addressed.
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From page 93... ...
A 1987 meta-analysis of this same issue focused on evidence from randomized controlled trials and the previous literature search supplemented with information from the Oxford Data Base of Perinatal Trials and from direct correspondence with individual investigators (51~. Variables were codified and, where possible, made comparable.
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From page 94... ...
Data from the randomized controlled trial that scored highest in an assessment of the quality of study design and implementation, however, indicated that electronic fetal monitoring combined with fetal scalp blood sampling could be used to identify infants at risk of neonatal seizures (521. That study had been suggested by pooled analyses of earlier randomized controlled trials (53~.
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From page 95... ...
Statistically valid methods to combine data across studies of varying quality and design, including data from case-control studies, will enable metaanalysts to maximize the value of their data syntheses (48~. One serious concern about quantitative reviews of the literature is that although meta-analysis is more explicit, it may be no more objective than a narrative review (621.
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From page 96... ...
First, one can compare the results of meta-analysis with those of narrative reviews to identify differences in interpretation and conclusions. In one study where a statistical procedure for summarizing research findings was compared with narrative reviews, it was found that the statistical reviewer was more likely to support the hypothesis both in direction and magnitude, although the basic recommendations did not differ between groups (681.
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From page 97... ...
Cumulating quality of life results in controlled trials of coronary artery bypass graft surgery. Controlled Clinical Trials 1985;6:289-305.
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From page 98... ...
Himel HN, Liberati A, Gelber RD et al. Adjuvant chemotherapy for breast cancer: A pooled estimate based on published randomized control trials.
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From page 99... ...
The eff~cacy of intrapartum electronic fetal monitoring. American Journal of Obstetrics and Gynecology 1987;156:2~30.
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From page 100... ...
A randomized trial of electronic fetal monitoring in premature labor. Obstetrics and Gynecology 1987;69:687-695.
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