744 e-Letters

  • No doubt that dehydration impairs exercise performances and risks health.
    Nina Stachenfeld

    I was pleased to see that physicians were at last taking an interest in physical activity as a method of preventive medicine. Further, I could not agree more that there are many claims made by manufacturers regarding improving performance that are unsupported by the literature (if there is any literature at all). In this note, I will not address anything other than claims made regarding fluid regulation, and do not supp...

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  • Non-normally distributed data
    Rajvir Singh

    To the Editor

    Title : Non-Normally Distributed Data

    Student t test (independent) compares the mean of an outcome variable for different subjects and widely but incorrectly believed that it is valid only for normally distributed outcomes even in very small samples; ignoring the fact that it is also valid for any distribution in large samples (1).

    Normality assumpt...

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  • Searching for open source software
    Elizabeth A Dodd

    The method chosen by Millard, Bru and Berger to search for open source electronic medical record systems has missed a number of packages. Instead of searching Google Scholar, a search through a generic search engine would have brought up the Wikipedia list http://en.wikipedia.org/wiki/List_of_open-source_healthcare_software This list contains a number of packages (the open source term) not seen on either on the included or...

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  • Views of Policymakers, healthcare workers, and NGOs, on HIV PrEP a multinational Qualitative Study. By Ana Wheelock et ,al: Published July 5, 2012
    Harriet Nakanyike

    Comment: From some of the focus group discussions with leadership hubs in Uganda from the project "Strengthening Nurses' Capacity in HIV Policy Development in Sub-Saharan Africa and the Caribbean"; a study entitled Effective Dissemination Strategies of HIV Work Policies to Nurses and Midwives in Kampala District, Uganda was conducted. It was noted that many policies are developed and given to nurses to implement without p...

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  • Re:Re:Re:Hypnotics' association with mortality or cancer: bias related to the study design and analysis
    Daniel F. Kripke

    Dr. Hallas, Dr. Andersen, and colleagues give us the very good news that they are working on a study of benzodiazepine-cancer association using the Danish Cancer Registry. Additional data that isolates benzodiazepine agonists and other hypnotics individually will be very welcome, as different benzodiazepine agonists may have different risks. Perhaps they can provide results from time-dependent Cox models. It will be...

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  • A helmet is not a safe and healthy "environment"
    Kay Teschke

    Bonyun and colleagues are concerned about a low prevalence of helmet use among BIXI cyclists, but do not study or mention other means of increasing cycling safety in Toronto. Bicycle helmets mitigate head injuries after a crash. Safety measures that prevent crashes from occurring are preferable because they prevent all types of injuries, and the personal, medical, labour and capital costs of crashes.

    All BIXI...

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  • 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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