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Jadad, et al 1 and Altman et al 2 claim that the properties of RevMan
are not relevant to the quality of Cochrane reviews. The point is,
however, that its properties are indicative of the psychology of Cochrane
reviewers. There is an emphasis, laudable from the Cochrane perspective,
of proving that selection bias for studies has not occurred. However, many
reviews in the pharmaceutical industry are for drugs that are in
development or newly developed. The so called “file-drawer problem” is
then of minimal concern. The sponsor and the regulator will know which
studies have been performed. Of greater concern is that these studies
should be analysed correctly. From this point of view RevMan is simply
inadequate. The acrimonious dispute earlier this year in the pages of the
Lancet regarding meta-analysis of screening for breast cancer, whatever
one thinks about the merits of the case, shows very clearly the inherent
dangers in fostering a mentality that relies on such approaches.
The so-called validation of the Oxman and Guyatt index 3 is a red
herring in the context of my criticism of Jadad et al 4. If any of the
nine validators (three of each of , “research assistants, clinicians with
research training and experts in research methodology,”) of this
particular instrument worked actively in drug development in the
pharmaceutical industry, Oxman and Guyatt did not think this worth
mentioning in the abstract of their paper.
I put it like this. Jadad et al compared ballet shoes and ski boots
at Covent Garden, and found the former to be superior. My interests are
different. I would carry out the same comparison at Val D’Isere and expect
to reach a different conclusion.
None of this is meant to imply any disrespect for the Cochrane
Collaboration, an organisation that I hold in great esteem. It simply
queries the value of publications in which collaborators award each other
brownie points.
Competing interests: Professor Senn is a consultant to the
pharmaceutical industry.
1. Jadad AR, Moher M, Browman GP, Booker L, Sigouin C, Fuentes M, et
al, BMJ 2000; 321:299
2. Altman DG, Deeks J, Clarke, M and Cates C. High quality reporting
of both randomised trials and systematic reviews should be priority BMJ
2000; 321:297.
3. Oxman AD, Guyatt GH. Validation of an index of the quality of
review articles. J Clin Epidemiol 1991; 44: 1271-1278
4. Jadad AR, Moher M, Browman GP, Booker L, Sigouin C, Fuentes M, et
al. Systematic reviews and meta-analyses on the treatment of asthma: a
critical evaluation. BMJ 2000; 320: 537-540
Ballet shoes and ski boots
Jadad, et al 1 and Altman et al 2 claim that the properties of RevMan
are not relevant to the quality of Cochrane reviews. The point is,
however, that its properties are indicative of the psychology of Cochrane
reviewers. There is an emphasis, laudable from the Cochrane perspective,
of proving that selection bias for studies has not occurred. However, many
reviews in the pharmaceutical industry are for drugs that are in
development or newly developed. The so called “file-drawer problem” is
then of minimal concern. The sponsor and the regulator will know which
studies have been performed. Of greater concern is that these studies
should be analysed correctly. From this point of view RevMan is simply
inadequate. The acrimonious dispute earlier this year in the pages of the
Lancet regarding meta-analysis of screening for breast cancer, whatever
one thinks about the merits of the case, shows very clearly the inherent
dangers in fostering a mentality that relies on such approaches.
The so-called validation of the Oxman and Guyatt index 3 is a red
herring in the context of my criticism of Jadad et al 4. If any of the
nine validators (three of each of , “research assistants, clinicians with
research training and experts in research methodology,”) of this
particular instrument worked actively in drug development in the
pharmaceutical industry, Oxman and Guyatt did not think this worth
mentioning in the abstract of their paper.
I put it like this. Jadad et al compared ballet shoes and ski boots
at Covent Garden, and found the former to be superior. My interests are
different. I would carry out the same comparison at Val D’Isere and expect
to reach a different conclusion.
None of this is meant to imply any disrespect for the Cochrane
Collaboration, an organisation that I hold in great esteem. It simply
queries the value of publications in which collaborators award each other
brownie points.
Competing interests: Professor Senn is a consultant to the
pharmaceutical industry.
1. Jadad AR, Moher M, Browman GP, Booker L, Sigouin C, Fuentes M, et
al, BMJ 2000; 321:299
2. Altman DG, Deeks J, Clarke, M and Cates C. High quality reporting
of both randomised trials and systematic reviews should be priority BMJ
2000; 321:297.
3. Oxman AD, Guyatt GH. Validation of an index of the quality of
review articles. J Clin Epidemiol 1991; 44: 1271-1278
4. Jadad AR, Moher M, Browman GP, Booker L, Sigouin C, Fuentes M, et
al. Systematic reviews and meta-analyses on the treatment of asthma: a
critical evaluation. BMJ 2000; 320: 537-540
Competing interests: No competing interests