Titre :
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Evidence from crossover trials : empirical evaluation and comparison against parallel arm trials. (2007)
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Auteurs :
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Dimitrios-N LATHYRIS ;
John-Pa IOANNIDIS ;
Thomas-A TRILCALMOS ;
Tufts University. School of Medicine. Department of Medicine. Institute for Clinical Research and Health Policy Studies. Boston. MA. USA ;
University of loannina. School of Medicine. Department of Hygiene and Epidemiology. Clinical Trials and Evidence-Based Medicine Unit. Ioannina. GRC
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Type de document :
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Article
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Dans :
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International journal of epidemiology (vol. 36, n° 2, 2007)
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Pagination :
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422-430
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Langues:
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Anglais
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Mots-clés :
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Essai comparatif
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Essai thérapeutique
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Evaluation
;
Etude comparée
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Résumé :
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[BDSP. Notice produite par INIST-CNRS gR0xrODm. Diffusion soumise à autorisation]. Background : We aimed to evaluate empirically how crossover trial results are analysed in meta-analyses of randomized evidence and whether their results agree with parallel arm studies on the same questions. Methods : We used a systematic sample of Cochrane meta-analyses including crossover trials. We evaluated the methods of analysis for crossover results and compared the concordance of the estimated effect sizes in crossover vs parallel arm trials. Results : Of 334 screened reviews, 62 had crossover trials. Of those, 33 meta-analyses performed quantitative syntheses involving two-arm two-period crossover trials. There was large variability on how these trials were analysed ; only one of the 33 meta-analyses stated that they used the data from both the first and second period with an appropriate paired approach. Nine meta-analyses used the first period data only and 14 gave no information at all on what they had done. Twenty-eight meta-analyses had both crossover n=137, sample size n=7162) and parallel arm (n=132, sample size n=11 398) trials. Effect sizes correlated well with the two types of designs (p=0.72). Differences on whether the effect had a P
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