138 e-Letters

  • The Cochrane HPV vaccine review was incomplete and ignored important evidence of bias: Response to the Cochrane editors

    The Cochrane HPV vaccine review was incomplete and ignored important evidence of bias: Response to the Cochrane editors

    Lars Jørgensen, LJ (lj@cochrane.dk), 1
    Peter C. Gøtzsche, PCG (pcg@cochrane.dk), 1
    Tom Jefferson, TJ (tj@cochrane.dk), 1

    1Nordic Cochrane Centre, Rigshospitalet 7811, Tagensvej 21, 2100 Copenhagen, Denmark.


    In a report uploaded on the Cochrane.org website on 3 September 2018 (1), Cochrane’s Editor in Chief and Deputy Editor in Chief responded to our analysis published in BMJ Evidence-Based Medicine on 27 July 2018 (2) of the Cochrane review of the HPV vaccines published on 9 May 2018 (3).

    The Cochrane editors acknowledge (1) that our analysis (2) addresses the importance of the selection of data sources for reviews, and we hope that Cochrane will take the threat posed by reporting bias (4) more seriously by using clinical study reports, rather than journal publications.

    The Cochrane editors claimed that we had “substantially overstated” our criticisms and they concluded that “Jørgensen et al made allegations that are not warranted and provided an inaccurate and sensationalized report of their analysis” (1).

    Here we address the Cochrane editors’ findings and present our further assessment and additional findings.

    In summary, we found that our analysis (2) was appropriat...

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  • This is a public matter and not just an institutional one

    Back in May I submitted a comment to the review by Aubyn et al, and when it was not published received an assurance from Cochrane admin that was because the site was undergoing up-date. I am dismayed but not surprised to find that it never appeared, though it is still germane:-

    "It concerns me that the authors of this study failed to contest the validity of trials that did not mostly take place against genuine placebo (i.e. saline), and even use the term "placebo" repeatedly. Do they not bear a huge responsibility by not taking this issue on, as if it is all right for this kind of methodology to become a norm of modern "scientific" practice and as something which does not affect the meaning and usefulness of the safety results?

    "Ordinary citizens, most of whom will have learned about good scientific practice at school, might assume that these trials were against genuine placebo and I find no clear explanation of the issue here, let alone in the "Plain Language Summary"."

    I was obviously stating the issue in a simplistic manner. The public probably mostly believe that the science behind these products would have been conducted at the highest standard before marketing, but this is very far from evident - and evident at a level which they are more than capable of understanding. Yet they continue to be shielded from the truth. The authors and this journal ought to be commended for standing against the profession...

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    The Cochrane Review of the HPV vaccine states :

    "In older women, vaccinated between 25 to 45 years of age, the effects of HPV vaccine on precancer are smaller, which may be due to previous exposure to HPV. The risk of precancer associated with HPV16/18 is probably reduced from 145/10,000 in unvaccinated women to 107/10,000 women following HPV vaccination (moderate certainty). The risk of any precancer is probably similar between unvaccinated and vaccinated women (343 versus 356/10,000, moderate certainty)."

    Cochrane estimates a significant effect of the vaccine on HPV 16/18 associated precancer in the 25-45 age group, but that effect disappears when risk of precancer of all (HPV) types is calculated. It is a matter of simple logic that for the positive (desired) effect on type 16/18 precancer to be offset in this way, the vaccine must have a corresponding negative (undesired) effect on precancer associated with other HPV types.

    The observation holds for all age groups, but is more pronounced in the older group. It is reasonable to assume that if one took, say, a 35 to 45 years old group, the total undesired result of the HPV vaccination could be statistically significant.

    If my reading of these numbers is too simplistic, it would be good to get a clarification, since the quoted passage appears right in the Summary with no further comments.

    In Europe, the vaccine is routinely recommended to women of all ages.


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  • More than 20,000 systematic reviews were published in 2017

    The number of systematic reviews being published each year is actually much larger than the already impressive number of 10,000 quoted. In 2017 over 20,000 were published; 20,661 are cited in the KSR Evidence database in early August 2018. KSR Evidence, includes all systematic reviews and meta-analyses published since 2015 and for many reviews provides a critical appraisal and a short, accessible bottom line. www.ksrevidence.com

  • Retraction notices in PubMed

    I searched PubMed for the retraction notices. The 3 retracted articles published by Elsevier have no retraction notices in PubMed. Retraction notices for the 2 articles in the Journal of the American Society of Hypertension were published in vol. 9, issue 10, this issue is indexed in PubMed and articles citations are in PubMed but the two retraction notices are missing. "Publishers of journals in PubMed must submit citation and abstract" (PubMed FAQ for publishers), these two notices should normally have been submitted by the publisher. As for the article published in the European Journal of Pharmaceutical Sciences, no retraction notice was found, information about the article being retracted is available in the original article but, as no retraction notice seems to be available, there is no information about the retracted status in PubMed. As PubMed is often the source used by researchers doing a study on retractions of articles (e.g. PMID: 28683764, PMID 26797347, PMID: 24928194) it is important to find this information in the database. Publishers should always publish retraction notices for retracted articles and submit the citations to PubMed when the journal is indexed in this database.

  • Response to Brodersen et al’s ’Overdiagnosis: what it is and what it isn’t'

    In their editorial, Brodersen et al. present two types of overdiagnosis. Their two types appear to be identical to two types of overdiagnosis we identified in research published in 2016 (Rogers WA and Mintzker Y. Getting clearer on overdiagnosis. J Eval Clin Prac 2016;22: 580-587). In that paper, we provide a detailed account of maldetection overdiagnosis and misclassification overdiagnosis, together with an analysis of the relevance of these two different types.
    This matter, including our request for a correction, is fully explained in our letter published in this journal: Response to Brodersen et al’s ’Overdiagnosis: what it is and what it isn’t' (http://ebm.bmj.com/content/early/2018/03/29/bmjebm-2018-110948).

  • Further research in low dose CT scan for suspected appendicitis.
    Dr. Paul V Puthussery

    Dear Editor,

    We read with great interest the recent article written by William Rogers et al on the Harms of CT scanning prior to surgery for suspected appendicitis(1). It highlights the radiation risk of cancer while routinely performing an abdominal CT scan on an otherwise healthy patient with symptoms suggestive of appendicitis. This radiation risk of cancer becomes all the more important in patients with 'ne...

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  • Re:Further research in low dose CT scan for suspected appendicitis.
    William D Rogers

    We share your enthusiasm for the current efforts to reduce radiation exposure associated with the use of CT scanning and agree with your assertion that performance of appendectomy without scanning will inevitably lead to more negative appendectomies. We are confident though based on the NHS laparoscopic appendectomy statistics reviewed by Omar and Clark in the Annals of Surgery that those negative appendectomies are asso...

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  • Inaccurate radiation exposure calculation
    Nigel D'Souza

    Dear Editor,

    Dr Rogers et al have astutely pointed out the dangers of routine CT assessment of right iliac fossa pain in the paediatric population. I agree wholeheartedly that the role of clinical judgement, alongside observation and serial examination remain critical. Ultrasonography and MRI are additional valuable diagnostic adjuncts that do not incur a radiation dose to patients.

    I would question the da...

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  • Re:Inaccurate radiation exposure calculation
    William D. Rogers

    Dear Editor,

    You are correct that protocols and improved technology have led to reductions in radiation exposure from CT scanning at some hospitals. I would suggest though that the resultant reduction in the risk of fatal cancer due to imaging does not affect the conclsion of the paper. If a laparotomy on a healthy young patient carries no risk of death and CT scanning imposes a risk of death the decision to perfor...

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