Titre :
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Comparison of evidence of treatment effects in randomized and nonrandomized studies. (2001)
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Auteurs :
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John-Pa IOANNIDIS ;
Despina-G CONTOPOULOS-IOANNIDIS ;
Anna-Bettina HAIDICH ;
Styliani-I KOKORI ;
Joseph LAU ;
Nikos PANTAZIS ;
Maroudia PAPPA ;
Maria-G TEKTONIDOU ;
Clinical Trials and Evidence-Based Medicine Unit. Department of Hygiene and Epidemiology. University of Ioannina School of Medicine. Ioannina. GRC ;
Department of Hygiene and Epidemiology. University of Athens School of Medicine. Athens. GRC ;
Division of Clinical Care Research. Department of Medicine. Tufts University School of Medicine. Boston. MA. USA
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Type de document :
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Article
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Dans :
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JAMA - Journal of the american medical association (vol. 286, n° 7, 2001)
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Pagination :
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821-830
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Langues:
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Anglais
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Mots-clés :
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Essai comparatif
;
Essai thérapeutique
;
Epidémiologie
;
Méthodologie
;
Etude comparée
;
Evaluation
;
Homme
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Résumé :
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[BDSP. Notice produite par INIST-CNRS R0xyz9bN. Diffusion soumise à autorisation]. 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 studies (r=0.75 ; P<. however nonrandomized studies tended to show larger treatment effects vs p="009)." between-study heterogeneity was frequent among randomized trials alone and very the summary results of types designs differed beyond chance in cases discrepancies were less common when only prospective considered occasional differences sample size timing publication also noted between discrepant studies. natural logarithm odds ratio by at least varied trials.>
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