eLetters

735 e-Letters

  • Correction to author affiliations
    Editorial Office BMJ Open

    Author affiliation 3 should read NWORTH, Bangor University, Bangor, UK

  • Re:No evidence that oral contraceptive use is associated with prostate cancer mortality: further observations
    David Margel

    We thank Drs Cherrie and MacCalman for their thoughtful comments. However the first step in any analysis is exploring the variables. When examining the distribution of women use of vaginal barriers world- wide, one notices that no country reports more than 5% of woman using this mode of contraception, and only 9 countries have over 1% use of vaginal barriers. Clearly this variable cannot be entered at face value. When w...

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  • There is no need for further placebo-controlled trials
    Evan Mayo-Wilson

    To the Editor:

    We concur with Fisker et al. that factors moderating and mediating the effect of vitamin A supplementation on mortality are not fully understood.[1] Further observational studies could elucidate this relationship. New trials might examine the impact of delivering vitamin A at different times of year or with different doses and frequencies; however, we disagree with Fisker et al. that further tri...

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  • Misleading conclusion with serious negative health outcome
    Chew Boon How

    Dear BMJ Open Editorial,

    we appreciate the effort of the authors in looking into the 30-year mortality outcomes of their initial cohorts, who were stratified into different occupational work demands, adjusted for some co-morbidities, risk factors and social classes. It was reassuring that the established cardiovascular risk factors of smoking and hypertension were indeed true much earlier than we aware. However...

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  • No evidence that oral contraceptive use is associated with prostate cancer mortality: further observations
    John W. Cherrie

    We are pleased that Margel and Fleshner recognize the data errors in their original manuscript [1], which have a dramatic impact on the outcome of the ecological analysis [2]. Using the correct dataset and extending the analysis to include all countries, which we agree is appropriate, the authors report that the correlation between oral contraceptive use and prostate cancer mortality was much reduced (Pearson correlation...

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  • Is there substance behind the headline?
    Luke D Sayers

    'Chronic Fatigue syndrome affects 1 in 100 pupils'

    This statement featured prominently on the BBC website and drew me first to press article and then the study. It seemed like reasonable research on first glance, it involved 2855 pupils and was published in a BMJ journal. However on closer inspection, the study is flawed.

    The authors present a clear agenda that they feel CFS/ME remains undiagnosed an...

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  • Uncontrolled study proves little about value of therapy received
    Tom P. Kindlon

    This paper (1) includes data on two separate (but related) issues: (i) the prevalence of diagnosed and undiagnosed Chronic Fatigue Syndrome/Myalgic Encephalomyelitis ("CFS/ME") (NICE criteria (2)) in children aged 11-16 and (ii) information on how they fared when they received therapy at the CFS clinic. The relative rigour that is brought to the first set of data may mean some may miss that many questions remain about th...

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  • Research is not convincing
    Des Spence

    I am concerned by the level of coverage this article has received. For this is a service provision descriptive pilot involving a tiny group of just 23 children. It is short , non randomised, has no controls and interventions completely unblinded. There is also an issue around commissioning bias , for the investigating group clearly believe that CFS is underdiagnosised in children. The Radio coverage presented considera...

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  • Re:Oral contraceptive use is not associated with prostate cancer
    David Margel

    We are thankful for Dr Cherrie`s astute observations. After careful review of our data it appears that we indeed miscoded several points in our data set, which have resulted in an error in the analysis. We therefore decided to make sure our hypothesis is in reality supported by the data. We re-analyzed the correlation between mode of contraceptive use and prostate cancer (PCa)- using data from all countries available on t...

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  • Oral contraceptive use is not associated with prostate cancer
    John W. Cherrie

    Margel and Fleshner (1) present results from an ecological study of associations between oral contraceptive (OC) use and prostate cancer. They hypothesize that men inadvertently ingest OCs or their by-products, passed from female urine into the environment or drinking water, and that the consequent increased low-level oestrogen exposure causes prostate cancer. The authors used data from a stratified random sample of countr...

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