1255 e-Letters

  • bias and confounding
    Ingrid Muehlhauser

    There are major concerns related to confounding and bias in this study. More intensive medication in the obese subjects is obviously mainly due to twice as high prevalence rates of hypertension and diabetes compared to subjects with normal BMI. Do the authors suggest that diabetes and hypertension improve life expectancy? Statin use was apparently not different across BMI categories. On the other hand, antidabetic drug t...

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  • Re:Adjustment or over-adjustment for 'TB incidence in the country of birth'?
    Guy B. Marks

    We thank the correspondents Min and Gyorkos for their comments on our paper, which focus on the appropriateness of adjustment for confounding in the analysis. We do not agree that the analysis suffers from over- adjustment for confounding. Over-adjustment occurs when a factor that is on the casual pathway between the main effect (exposure of interest) and the outcome is included as covariate. The decision about whether a fa...

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  • Re:Conflict of interest: response to Ms Colella
    Daniel F. Kripke

    Please note that my co-authors have approved our manuscript, but Dr. Langer and Dr. Kline have no previous publications about hypnotic drugs and no affiliation with the www.DarkSideOfSleepingPills.com web site. Some people would think it scientifically proper that I participated in a new study which overcomes some of the limitations of my previous scientific studies, along with co-authors who have no previous biases or...

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  • Conflict of interest
    Angela M Colella

    Dear Editor: I appreciated and read Dr. Kripke's manuscript with interest. He and his co-authors present many considerations healthcare providers should acknowledge when prescribing hypnotics. Hypnotics, like all medications, have inherent risks. I was disappointed however, to read about Dr. Kripke's affiliation, or hosting, of the website www.DarkSideOfSleepingPills.com. In my opinion, this affiliation casts a signi...

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  • Things May Not Be As They Seem
    Jose Maria Lopez Lozano

    Sir, In their recent study from Oxfordshire, Wyllie and colleagues questioned the role that intensive infection control measures have played in controlling the epidemic of MRSA in hospitals in their region. [1] The authors suggest that effects of introducing intensive interventions for MRSA may have been limited, given that stabilization and subsequent declines in rates of MRSA occurred prior to such measures, and were...

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  • Response to Article: Baby knows best? The impact of weaning style on food preferences and body mass index in early childhood in a case-controlled sample
    Smita Nambiar

    Dear Madam,

    This letter is in response to the article entitled 'Baby knows best? The impact of weaning style on food preferences and body mass index in early childhood in a case-controlled sample' (doi 10.1136/bmjopen-2011- 000298).

    In this article, the impact of the 'how' of introduction to solid feeding (self-feeding finger foods versus spoon-feeding), on food preference, food consumption, BMI and p...

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  • Propensity score matching to minimize confounding by indication
    Sujit D Rathod
    The authors made a concerted effort to control for confounding in the design and analysis phase of this paper, and correctly stated that unmeasured confounding is a limiting feature of the results. Given the understandable concerns about confounding by indication, another approach the authors may wish to consider is propensity score matching for the analysis. Indeed, they should be able to show that a given hypnotic user had some...
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  • Adjustment or over-adjustment for 'TB incidence in the country of birth'?
    Sooyeon Min

    The recent paper by Dobler et al. (2012) highlights the challenge of variable selection and adjustment in multivariate analyses [1]. The authors state that including the potentially confounding variable 'TB incidence in the country of birth' was one of the major strengths of their study. TB incidence in the country of birth is indeed an important predictor of the risk of developing TB - but it may not be a true confounde...

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  • Re:Are we sure that baby-led weaning is nutritionally adequate and can prevent childhood obesity?
    Ellen Townsend

    In response to the letter from ECOG we would to like highlight that the criticisms levied against our research were already discussed explicitly in our paper and the limitations, for example, of parental self -report were mentioned up front in the article in the summary box. For precisely the reasons mentioned by the ECOG group we generated a matched sample from our total sample in which we controlled for age. The matched...

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  • Response: "Hypnotics' association with mortality or cancer: a matched cohort study"
    Devonne M Ryan

    Dr. Daniel Kripke,

    Thank you for you article entitled "Hypnotics' association with mortality or cancer: a matched cohort study," I enjoyed reading it and found it to be especially interesting. Nonetheless, I have a few comments and questions related to your research area and your article. Firstly, I thought the research design you choose was suitable for the nature of the research. The matched cohort study was...

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