Evidence from crossover trials: empirical evaluation and comparison against parallel arm trials
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Ημερομηνία
Συγγραφείς
Τίτλος Εφημερίδας
Περιοδικό ISSN
Τίτλος τόμου
Εκδότης
Περίληψη
Τύπος
Είδος δημοσίευσης σε συνέδριο
Είδος περιοδικού
peer-reviewed
Είδος εκπαιδευτικού υλικού
Όνομα συνεδρίου
Όνομα περιοδικού
Int J Epidemiol
Όνομα βιβλίου
Σειρά βιβλίου
Έκδοση βιβλίου
Συμπληρωματικός/δευτερεύων τίτλος
Περιγραφή
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 = 7,162) and parallel arm (n = 132, sample size n = 11,398) trials. Effect sizes correlated well with the two types of designs (rho = 0.72). Differences on whether the summary effect had a P < 0.05 or not were common due to limited sample sizes. The summary relative odds ratio for parallel arm vs crossover designs for favourable outcomes was 0.87 (95% CI, 0.74-1.02). CONCLUSIONS: Crossover designs may contribute evidence in a fifth of systematic reviews, but few meta-analyses make use of their full data. The results of crossover trials tend to agree with those of parallel arm trials, although there was a trend for more conservative treatment effect estimates in parallel arm trials.
Περιγραφή
Λέξεις-κλειδιά
*Cross-Over Studies, *Evaluation Studies as Topic, Female, Humans, Male, *Meta-Analysis as Topic, Randomized Controlled Trials as Topic/*standards
Θεματική κατηγορία
Παραπομπή
Σύνδεσμος
http://www.ncbi.nlm.nih.gov/pubmed/17301102
http://ije.oxfordjournals.org/content/36/2/422.full.pdf
http://ije.oxfordjournals.org/content/36/2/422.full.pdf
Γλώσσα
en
Εκδίδον τμήμα/τομέας
Όνομα επιβλέποντος
Εξεταστική επιτροπή
Γενική Περιγραφή / Σχόλια
Ίδρυμα και Σχολή/Τμήμα του υποβάλλοντος
Πανεπιστήμιο Ιωαννίνων. Σχολή Επιστημών Υγείας. Τμήμα Ιατρικής