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Comparison of evidence of treatment effects in randomized and nonrandomized studies (2001)
| Venue: | JAMA |
| Citations: | 7 - 0 self |
BibTeX
@ARTICLE{Ioannidis01comparisonof,
author = {John P. A. Ioannidis and Anna-bettina Haidich and Nikos Pantazis and Styliani I. Kokori and Maria G. Tektonidou and Despina G. Contopoulos-ioannidis},
title = {Comparison of evidence of treatment effects in randomized and nonrandomized studies},
journal = {JAMA},
year = {2001},
pages = {821--830}
}
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Abstract
A randomized clinical trial may produce different results than a non-randomized trial, according to researchers who used meta-analysis to compare 240 randomized trials and 168 non-randomized trials of 45 different treatments. Randomization means that patients are assigned randomly to either the treatment group or the group that receives a placebo, or inactive substance. © COPYRIGHT 2001 American Medical Association Context There is substantial debate about whether the results of nonrandomized studies are consistent with the results of randomized controlled trials on the same topic. Objectives To compare results of randomized and nonrandomized studies that evaluated medical interventions and to examine characteristics that may explain discrepancies between randomized and nonrandomized studies. Data Sources MEDLINE (1966-March 2000), the Cochrane Library (Issue 3, 2000), and major journals were searched. Study Selection Forty-five diverse topics were identified for which both randomized trials (n=240) and nonrandomized studies (n=168) had been performed and had been considered in meta-analyses of binary outcomes. Data Extraction Data on events per patient in each study arm and design and characteristics of each study considered in each meta-analysis were extracted and synthesized separately for randomized and nonrandomized studies. Data Synthesis Very good correlation was observed between the summary odds ratios of randomized and nonrandomized
Keyphrases
nonrandomized study treatment effect non-randomized trial randomized trial study arm american medical association context data source medline treatment group study selection forty-five diverse topic different treatment randomized clinical trial medical intervention substantial debate inactive substance data extraction data cochrane library binary outcome data synthesis good correlation summary odds ratio different result major journal
