1458 e-Letters

  • Low vitamin D concentration may explain the high death rate from severe pandemic type A(H1N1) influenza for pregnant women in China
    William B. Grant

    The paper by Li et al. [1] reports that pregnant women had significantly increased risk of death associated with severe pandemic A(H1N1) infection than other groups. This finding was related to delays in getting to the hospital for antiviral treatment and being in the third trimester of pregnancy. While these conclusions are valid, there is a more fundamental underlying cause of the higher death rate for pregnant women: l...

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  • Corrigendum: Combination use of Beck Depression Inventory and two-question case-finding instrument as a screening tool for depression in the workplace
    Branko Aleksic
    In this article, supplementary fig. 3 appeared incorrectly. The correct label on the Y-axis of the graph depicted in supplementary fig. 3 is "BDI score". However, after correction, our original inference remains same.

    Conflict of Interest:

    None declared

  • Semen quality in young men twenty years after Carlsen et al.
    Shanna H. Swan

    Dear Editor, Twenty years ago Carlsen et al. analyzed data from 14,947 men included in 61 papers published between 1938 and 1991 and concluded that sperm concentration had declined significantly over the prior 50 years (1). Numerous criticisms and analyses followed this landmark publication. Among these, our detailed reanalysis found that this conclusion was, indeed, supported by the underlying studies (2,3). Many other i...

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  • Re:Re:Hypnotics' association with mortality or cancer: bias related to the study design and analysis
    Jesper Hallas

    We appreciate the response from Dr. Kripke, although we are afraid it supports our notion of a bias in their selection of reference cohort rather than reassure us about the opposite.

    In their study, non-users of hypnotics were required to have no hypnotic prescriptions at any time in their entire follow-up. However, in a cohort study, exposure that occurs after an endpoint should not be taken into consideration....

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  • Alicia I. Arbaje

    I read with great interest the article by Woz, et al. on gender as a risk factor for 30 days post-discharge hospital utilisation. The authors state that to their knowledge the issue of gender has not been the focus of studies on post-discharge hospital utilsation. I would like to refer the authors to a nationally representative study of US Medicare data we published in The Gerontologist in 2008 (Arbaje, et al., vol. 48...

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  • Further data available in the Dryad repository
    Richard Sands

    Underlying data from this study is available from the Dryad data repository: http://datadryad.org/resource/doi:10.5061/dryad.f4688

    Krusche A, Cyhlarova E, King S, Williams JMG (2012) Data from: Mindfulness online: a preliminary evaluation of the feasibility of a web- based mindfulness course and the impact on stress. Dryad Digital Repository. doi:10.5061/dryad.f4688

    Conflict of Interest:

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  • Poor oral hygiene may be linked to cancer
    C. Albert Yeung

    There is no doubt that good oral hygiene is important; if dental plaque build up is left for a long time, it can lead to periodontal disease and tooth loss. This long-running cohort study suggests that poor oral hygiene during our 30s is associated with an increased risk of dying of cancer over nearly a quarter of a century.

    This study cannot prove that dental plaque levels either directly or indirectly cause c...

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  • Re:Hypnotics' association with mortality or cancer: bias related to the study design and analysis
    Daniel F. Kripke
    Replying to Dr. Andersen and colleagues, we appreciate their very learned statistical comments on our article. First, there seems to be a misunderstanding of our selection criteria. A patient who developed cancer before receiving a hypnotic would not have been included in either the hypnotic-prescribed or the control group, and therefore would not bias the study in regard to hypnotic-associated cancer incidence. Secondly,...
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  • Re:Is it hypnotics that kill, or is it psychiatric illness?
    Daniel F. Kripke
    In reply to Dr. Terkelsen and colleagues, I am greatly awed by the extensive literature review which they kindly offered with so much effort. Unfortunately, these colleagues ignored the point which we made in our article: Mallon et al. (reference 7) and Belleville (reference 8) have shown that control for depression does not substantially attenuate the mortality hazard associated with hypnotics. On the other hand, Patten e...
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  • Hypnotics' association with mortality or cancer: bias related to the study design and analysis
    Morten Andersen (1)

    In BMJ Open, Kripke et al have presented a study on risks associated with the use of hypnotics (1). In their two-in-one study, the authors report an about fourfold increased risk of death and a 35% increased risk of cancer when comparing users of hypnotics with non-users. The authors present the analyses as a cohort study using a survival analysis model with Cox regression. However, several approaches in both the study d...

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