1238 e-Letters

  • Reconciling hormone therapy effects in RCTs and observational studies
    Jacques E Rossouw

    Hartz et al1 analyzed the Women's Health Initiative (WHI) public use dataset in an attempt to reconcile certain divergent findings from clinical trials (CTs) of hormone therapy (HT) and observational studies (OS) primarily by extensive adjustment for confounders. Their conclusion that the WHI (and other observational studies) did not collect sufficient information to give reliable information about treatment effects appe...

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  • Renin-angiotensin-aldosterone system blockade may provide vascular protection in patients with Alzheimer's disease by reversing oxidative stress and inflammation
    Kwang K. Koh

    Gao Yang, et al's paper is timely important in delineating that centrally acting angiotensin-converting enzyme (ACE) inhibitors (CACE-Is), which cross the blood-brain barrier, are associated with a reduced rate of cognitive decline.1 Reduced rates of cognitive decline were seen in an unselected outpatient sample, prescribed CACE-Is, irrespective of the blood pressure readings or diagnosis of hypertension. The rate of decli...

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  • Re:Further concerns on methods, results and conclusions
    Evangelos Kontopantelis

    We thank Professor Hippisley-Cox and Dr O'Hanlon for their feedback on our BMJ Open paper (3, e003190). We address each point raised below:

    1.The authors have undertaken a cross-sectional study - this is weakest study design and the results of such studies can only ever signal associations rather than attribute causality. Limited information is provided on the 'adjustments' made in the analyses meaning the reade...

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  • Further concerns on methods, results and conclusions
    Julia Hippisley-Cox

    Dear Trish

    I'm afraid we also have many concerns regarding this paper in addition to those already raised by Mary Hawking.

    1. The authors have undertaken a cross-sectional study - this is weakest study design and the results of such studies can only ever signal associations rather than attribute causality. Limited information is provided on the 'adjustments' made in the analyses meaning the reader...

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  • Re:So many concerns, where to begin?
    Evan Kontopantelis

    Dear Mary

    Thank you for your diligent reading and useful comments. To answer the points you raise:

    1) The issue with table 3 has already been identified. Basically the labels for the SHA are wrong. Apologies for this.

    2) In the database from the HSCIC SystmOne was labelled as appears on the paper, ProdSysOneX. Embarrassingly, I did not query the name

    The BMJ has already been notified a...

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  • So many concerns, where to begin?
    Mary Hawking

    There would appear to be a number of inaccuracies in this article which I am very much afraid make the conclusions hard to sustain - and I would urge anyone thinking of using this article to guide their choice of GP IT system at any level to think again!

    Just a few points:- The description of GP computing is wrong: GP systems became 50% reimbursable in 1990 - not 1998 - and the reason was to bring them under DH...

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  • The validity of Carpenter's arguments from a statistical point of view
    Katharina Schueller
    Imputation of missing data
    The REALCOM-IMPUTE imputation method, mentioned in the appendix of the article by Carpenter et al., is based on the assumption that the value of the variable of interest is missing completely at random (MCAR) or that the missing value can be explained by other variables and does not depend on the (unknown) value of the variable of interest itself (MAR, missing at random). Initial an...
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  • Authors' Reply to responses on BMJ Open to Bed sharing when parents do not smoke: Is there a risk of SIDS? An individual level analysis of five major cases-control studies.
    Robert Carpenter

    Dr. O'Hagan's suggestion that SIDS may be due to maternal vitamin C deficiency seems unlikely because baby formula milk includes vitamin C supplement. We would therefore expect on his hypothesis that bottle fed babies would, if anything, be at lower risk than breast fed infants, which is not the case(1,2).

    Professor Byard and Dr Hunsaker are concerned that the possibility of accidental suffocation was not addres...

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  • Grant preparation time: the law of diminishing returns prompts a rethink on the application and review process
    Andrew W. Taylor-Robinson

    Using data from the 2012 Australian National Health and Medical Research Council (NHMRC) application round, Herbert and colleagues provide an estimate of the cost (in dollars and hours) of preparing a research grant. They conclude that more time spent by a chief investigator preparing a proposal does not increase the chance of being awarded a grant and that the relentless polishing of grant text, to the extent of poring o...

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  • Adressing the underestimated risk-problem in primary care's low prevalence sector
    Martin Konitzer

    This article is shedding some light on the underestimated problem of malpractice in primary care. In primary care most encounters finish without diagnoses but with classifications of symptoms. According to RN Braun's "Casugraphy" (1982) we have a biaxial tool describing and hardening results of encounters following a Pareto- or power law distribution. This distribution features two characteristics: 20% of "diagnoses" cou...

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