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Dr. Hutchings` response after estimating the burden of occupational cancer in Britain: all three areas of concern remain when examining the example of shift-work (Thomas C. Erren, 21 February 2012)

Are the (i) causal, (ii) practical and (iii) methodological areas of concern [1] with regard to attributing breast cancer risks to shift-work, in particular, and the burden of disease (BOD) calculations, in general, taken care of by Dr. Hutchings` recent response [2]?... read full comment

Comment on: Erren et al. Epidemiologic Perspectives & Innovations, 8:4

Response to Erren and Morfeld, 2011 (Sally Hutchings, 13 January 2012)

We have read the paper by Erren and Morfeld (2011) [1] with interest and offer the following comments on the concerns expressed by them about our work estimating the burden of occupational cancer in Britain [2]. We agree with Erren and Morfeld that burden of disease studies inform public health decision making by providing useful indicators of the contribution of different risk factors and indeed the results from our study are already being used for this purpose.... read full comment

Comment on: Erren et al. Epidemiologic Perspectives & Innovations, 8:4

The Stratify macro has been updated and enhanced (Klaus Rostgaard, 19 November 2010)

Dear reader,

In the fall of 2010 I updated and enhanced the stratify macro substantially.

Most of the things that appear as post-processing in this paper is now performed by default internally in the macro. Also the BRTF statement has been replaced by the SRTF statement which has exactly the same syntax, but is more general. Most examples in the paper have to be modified slightly to work in the same way (often just the addition of COMPLETE=no as an option). These changes have been made in the textfile containing the macro and sample code. The enhancements made have made the macro (relatively) more useful for Cox regression, which can now be performed directly on output data from the stratify macro. Also see my new suggestions for making a “period” time... read full comment

Comment on: Rostgaard Epidemiologic Perspectives & Innovations, 5:7

a few clarifications (John Cologne, 19 November 2010)

This excellent article by Turner, Dobson, and Pocock is highly welcomed and long overdue. A couple of points made in the article will be obvious to most statisticians, but might benefit from some clarification for persons with less sophisticated statistical training or experience.

First of all, one example is given where a null hypothesis of no effect could be rejected with two groups but not four. This is counter-intuitive to the statement elsewhere in the article that "dichotomies should be avoided". The reason is because it depends on the underlying, unobserved true effect. How many groups and where to place cutpoints depends heavily on the shape of the effect. I have encountered situations where it was possible for data with a strong linear relationship to... read full comment

Comment on: Turner et al. Epidemiologic Perspectives & Innovations, 7:9

Re: Estimating uncertainty in observational studies of associations between continuous variables: Example of methylmercury and neuropsychological testing in children. Reply by M. Goodman, P. Mink and L. Barraj (Michael Goodman, 06 December 2007)

We thank Drs. Budtz-Jørgensen, Keiding and Grandjean for their comments. The following is our response to the specific concerns raised in their letter.1. … the paper rests on an apparent disagreement between the findings of epidemiological studies carried out in the Seychelles and the Faroe Islands. However, we have previously shown that the results of the Seychelles study are sufficiently variable to be in statistical agreement with a mercury-associated deficit on the Boston Naming Test reported from the Faroe Island. RESPONSE: Systematic errors are unavoidable in observational epidemiology, and it is reasonable to assume that neither the Seychelles Child Development Study (SCDS) nor the Faroe Islands Study (FIS) are immune to imperfections of study design and implementation.... read full comment

Comment on: Goodman et al. Epidemiologic Perspectives & Innovations, 4:9

Second response by M. Goodman, L. Barraj, P. Mink and D. Flanders (Michael Goodman, 06 December 2007)

It is not correct that we “assumed a correlation of 0.8 between an unmeasured confounder and the BNT response.” Rather we assumed a range of correlations with a minimum of 0.2 and a maximum of 0.8. Budtz-Jorgensen and colleagues suggest that unaccounted confounding did not affect their study results, thereby offering an assumption of their own. We accepted this assumption and re-ran the sensitivity analyses to correct only for information and selection bias. The results were as follows. For the Faroe Islands Study (FIS) after adjusting for information and selection bias the slope (SE) changed from -0.0190 (0.0063) as originally reported by the FIS group to -0.0022 (0.0392). As a reminder, adjustment for selection, information and confounding bias in our paper resulted in a... read full comment

Comment on: Goodman et al. Epidemiologic Perspectives & Innovations, 4:9

rejoinder (Esben Budtz-Jorgensen, 06 December 2007)

Aurthors: Esben Budtz-Jørgensen and Niels Keiding (Department of Biostatistics, University of Copenhagen, Denmark)Philippe Grandjean (University of Southern Denmark, Odense, Denmark; and Harvard School of Public Health, Boston, MA, USA)As a rejoinder to Goodman et al.'s response, we would agree that sensitivity analyses can be useful when evaluating evidence from observational studies. However, such calculations are informative only if based on realistic assumptions about the unknown parameters. Thus, an observed exposure-response relationship can always be removed by postulating the presence of a strong unmeasured confounder. Correlations between the confounder and the exposure and response parameters should therefore be realistic and based on available evidence. In their analysis of... read full comment

Comment on: Goodman et al. Epidemiologic Perspectives & Innovations, 4:9

Extreme assumptions are unnecessary (Esben Budtz-Jorgensen, 14 November 2007)

Authors: Esben Budtz-Jørgensen and Niels Keiding (Department of Biostatistics, University of Copenhagen, Denmark)Philippe Grandjean (University of Southern Denmark, Odense, Denmark; and Harvard School of Public Health, Boston, MA, USA)The paper by Goodman et al. (1) aims at modeling the impact of extreme uncertainties on the results of an observational study, in this case the risk of developmental neurotoxicity associated with maternal dietary exposure to methylmercury during pregnancy. Thus, the paper rests on an apparent disagreement between the findings of epidemiological studies carried out in the Seychelles and the Faroe Islands. However, we have previously shown that the results of the Seychelles study are sufficiently variable to be in statistical agreement with a mercury-... read full comment

Comment on: Goodman et al. Epidemiologic Perspectives & Innovations, 4:9

Klemper's Biased Judgement (Stanley Gage, 17 November 2006)

Klemper, in extrapolating the results of his study, argues in light of his results, that a 90 day antibiotic treatment does not provide any noticalbe improvement in patient health and, therefore, extended antibiotic treatment is of no value. The conclusion fails to take notice of the fact that an equally vaild argument based on this study outcome would be that a 90 day antibiotic treatment is insufficient to provide any improvement in patient health and that longer duration antibiotic treament may be necesary to reduce or eliminate the efects of desseminatd Lyme.The real upshot of the issue of the results as published is to question that they were published at all. Publishing bad science is worse than publishing nothing. In the case of the Klemper article the author/researcher obviously... read full comment

Comment on: Cameron Epidemiologic Perspectives & Innovations, 3:12

Thanks for publishing the exellent article, Generalizability in two clinical trials of Lyme disease (Marisa Battilana, 17 November 2006)

Thanks you for publishing Dr. Cameron's exellent article, Generalizability in two clinical trials of Lyme disease.In my nearly two years as a volunteer in the Lyme community, I have met over 2,000 people who either have been personally affected by late stage Lyme disease or who know someone who has. The majority of the folks affected benefited greatly from extended treatment with antibiotics, most for more than just a few months. Many found out the hard way that they needed more than short term treatment: when taken off antibiotics, they relapsed within a short time. And, when they resumed treatment, they saw significant improvement.Articles like Dr. Cameron's are long overdue. Thank you.Marisa Battilana read full comment

Comment on: Cameron Epidemiologic Perspectives & Innovations, 3:12

NIH Headline Still Stands - Long Enough? (Phyllis Mervine, 17 November 2006)

Five years after the original flawed description of the New England Medical Center [aka Klempner] clinical trial was posted on NIH websites, thanks are due to Dr. Cameron for providing compelling evidence why it should be changed to “Chronic Lyme Disease Study Shows 3 Months of Antibiotic Treatment Inadequate.” As one of the patient representatives on the Advisory Panel for the NIH Clinical Trials, I so requested our NIH Lyme program officer Phil Baker in September 2001. Referring to other Panel members who had discussed the limited applicability of this treatment trial, I wrote: “We all know that the NEMC study was not designed to prove, could not prove and did not prove what your current headline suggests that it did prove. Patients are already being affected by the... read full comment

Comment on: Cameron Epidemiologic Perspectives & Innovations, 3:12

Chronic Lyme Disease Daniel Cameron Study (Peggy McCann, 17 November 2006)

Thank you for publishing Daniel Cameron's review on the Kempler clinical trials of lyme disease.The new IDSA guidelines are based on VERY selective research studies such as Kempler's paper. They conveniently and/or deliberately ignored over 18,000 conflicting articles and research studies published on Medline.I am very upset by the guideline's arrogant dismissal of patients who don’t get better in the time span and with the dose of antibiotics they deem appropriate. So those unfortunate enough to continue suffering multiple symptoms that don’t conform to their blue-print, are left without hope for getting their life back. Do you have any idea how awful that scenario is to patients and their families? Or to the family physicians who are told to treat no further, even though their... read full comment

Comment on: Cameron Epidemiologic Perspectives & Innovations, 3:12