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Alejandro R Jadad a Department of Clinical Epidemiology and
Biostatistics, McMaster University, Hamilton, Canada L8N 3Z5, b Institute of Health Sciences, University of Oxford,
Headington, Oxford OX3 7LF, c Foresight Consultants, Dundas, Ontario, Canada
L9H 2R5
Correspondence to: A R Jadad jadada{at}fhs.mcmaster.ca
Objective:
To evaluate the clinical, methodological, and reporting aspects of systematic reviews and meta-analyses on the
treatment of asthma and to compare those published by the Cochrane
Collaboration with those published in paper based journals.
Design:
Analysis of studies identified from Medline, CINAHL, HealthSTAR, EMBASE, Cochrane Library, personal
collections, and reference lists.
Studies:
Articles describing a systematic review or a
meta-analysis of the treatment of asthma that were published as a full
report, in any language or format, in a peer reviewed journal or the
Cochrane Library.
Main outcome measures:
General characteristics of
studies reviewed and methodological characteristics (sources of
articles; language restrictions; format, design, and publication status
of studies included; type of data synthesis; and methodological quality).
Results:
50 systematic reviews and meta-analyses were included. More than half were published in the past two years. Twelve
reviews were published in the Cochrane Library and 38 were published in 22 peer reviewed journals. Forced expiratory volume in one second was the most frequently used outcome, but few reviews evaluated the effect of treatment on costs or patient preferences. Forty reviews were judged to have serious or extensive flaws. All six
reviews associated with industry were in this group. Seven of the 10 most rigorous reviews were published in the Cochrane Library.
Conclusions:
Most reviews published in peer reviewed
journals or funded by industry have serious methodological flaws that
limit their value to guide decisions. Cochrane reviews are more
rigorous and better reported than those published in peer reviewed journals.
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