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PLoS One. 2016 Jul 13;11(7):e0159014. doi: 10.1371/journal.pone.0159014. eCollection 2016.

The Use and Reporting of the Cross-Over Study Design in Clinical Trials and Systematic Reviews: A Systematic Assessment.

Author information

1
Department of Biostatistics, University of Liverpool, Liverpool, United Kingdom.
2
Cochrane Cystic Fibrosis and Genetic Disorders Group, Liverpool, United Kingdom.
3
Chronic Disease Research Centre, The University of the West Indies, Barbados, West Indies.
4
Cochrane Editorial Unit, London, United Kingdom.

Abstract

BACKGROUND:

Systematic reviews of treatment interventions in stable or chronic conditions often require the synthesis of clinical trials with a cross-over design. Previous work has indicated that methodology for analysing cross-over data is inadequate in trial reports and in systematic reviews assessing trials with this design.

OBJECTIVE:

We assessed systematic review methodology for synthesising cross-over trials among Cochrane Cystic Fibrosis and Genetic Disorders Group reviews published to July 2015, and assessed the quality of reporting among the cross-over trials included in these reviews.

METHODOLOGY:

We performed data extraction of methodology and reporting in reviews, trials identified and trials included within reviews.

PRINCIPAL FINDINGS:

We reviewed a total of 142 Cochrane systematic reviews including 53 reviews which synthesised evidence from 218 cross-over trials. Thirty-three (63%) Cochrane reviews described a clear and appropriate method for the inclusion of cross-over data, and of these 19 (56%) used the same method to analyse results. 145 cross-over trials were described narratively or treated as parallel trials in reviews but in 30 (21%) of these trials data existed in the trial reports to account for the cross-over design. At the trial level, the analysis and presentation of results were often inappropriate or unclear, with only 69 (32%) trials presenting results that could be included in meta-analysis.

CONCLUSIONS:

Despite development of accessible, technical guidance and training for Cochrane systematic reviewers, statistical analysis and reporting of cross-over data is inadequate at both the systematic review and the trial level. Plain language and practical guidance for the inclusion of cross-over data in meta-analysis would benefit systematic reviewers, who come from a wide range of health specialties. Minimum reporting standards for cross-over trials are needed.

PMID:
27409076
PMCID:
PMC4943623
DOI:
10.1371/journal.pone.0159014
[Indexed for MEDLINE]
Free PMC Article

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