[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Wing: Descriptive Epidemiology by Any Other Name...



I guess I'm  not thinking clearly and getting dotty in my old age.  What I
thought Dan Strom was trying to say was that papers on both sides (or maybe
all sides) of this contentious issue (or any scientific issue for that
matter) should be judged using the same meter stick.  There was no personal
attack or criticism of you, Bernie, apparent to me, at any rate.  If
anything, what I thought Dan was trying to point out was that Wing's work
should be subject to the same rigorous evaluations that your work has been
subjected to.  He also expressed some of his personal views and preferences.

Perhaps the message can be better seen by looking at the key statement from
Strom, viz:

If you are upset by Wing yet celebrate Cohen, I ask that you examine why 
>> >descriptive studies are compelling in one case and not in the other.  To 
>> >me, the bottom line is that neither have data for individuals, neither 
>> >has meaningful control for confounders and biases, and no amount of 
>> >statistical analysis will change that.  Both fail to meet many of the 
>> >criteria presented by leading risk analysts. 

and exchanging Wing for Cohen and Cohen for Wing in the first line.  Seems
to me this is simply a call for scientific fairness. 

As for the difference between testing a LNT 'theory' and determining a dose
response relationship, I'm really confused.   Is not the LNT theory simply a
statement or representation or model of a dose-response relationship?  If
so, then is not testing it simply a determination of its validity, and hence
determining whether it is a (suitable) dose-response relationship?

Ron Kathren









>n Wed, 26 Feb 1997, Ron L. Kathren wrote:
>
>> Vintage Dan Strom -- clearly thought out, well put (albeit lengthy).
>>
>
>	--If someone does not understand the difference between testing a
>linear-no threshold theory and determining a dose-response relationship,
>he is surely not thinking clearly. 
>	If a person can't put his criticisms of a scientific work into a
>scientific paper or letter-to-the-editor suitable for publication, he is
>surely not thinking clearly.
> 
>Bernard L. Cohen
>Physics Dept.
>University of Pittsburgh
>Pittsburgh, PA 15260
>Tel: (412)624-9245
>Fax: (412)624-9163
>e-mail: blc+@pitt.edu
>
>Bernard L. Cohen
>Physics Dept.
>University of Pittsburgh
>Pittsburgh, PA 15260
>Tel: (412)624-9245
>Fax: (412)624-9163
>e-mail: blc+@pitt.edu
>
>
>On Wed, 26 Feb 1997, Ron L. Kathren wrote:
>
>> Vintage Dan Strom -- clearly thought out, well put (albeit lengthy).
>> 
>> When, oh when, are we going to get together on the work for ALOO?
>> 
>> Ron
>> 
>> >In 1877 Henle and Koch first addresssed association and causation (Evans 
>> >1976), and their work was revisited two decades ago (Rothman 1976).  Sir 
>> >Austin Bradford Hill published an influential work on association and 
>> >causation (Hill 1965).  Another perspective can be found in the work of 
>> >Susser (1991).  Canadian and U.S. leaders addressed the quality of 
>> >epidemiologic evidence under the title "Hierarchy of Evidence" (U.S. 
>> >Preventive Services Task Force 1989).  Most recently, the Federal Focus 
>> >expert panel explained why descriptive epidemiology studies don't get 
>> >much respect among risk analysts when they try to come to quantitative 
>> >conclusions (Graham et al. 1996).  
>> >
>> >I have always been critical of the application of descriptive 
>> >epidemiology (e.g., ecologic studies) to quantitative problems (Strom 
>> >1997, 1991a).  "Descriptive studies are generally viewed as useful for 
>> >identifying or formulating causal hypotheses, but not a sufficient to 
>> >test such hypotheses, because they lack data on individuals, such as 
>> >individual exposures, potential confounding exposures, factors affecting 
>> >individual susceptibility, and potential biases.  In contrast, studies 
>> >generally termed 'analytic' aim to establish risk factors for 
>> >populations and individuals by ascertaining individual exposures and 
>> >controlling for other variables such as gender, age, race, or exposure 
>> >to other agents that could affect risk estimates independently 
>> >(potential 'confounders'), potential study biases, and variations in 
>> >host susceptibility.  There are two main types of analytic epidemiology: 
>> >case-control and cohort studies..."  This quote is from a new book 
>> >written by an expert panel of risk assessors in 1995 entitled 
>> >"Principles for Evaluating Epidemiologic Data in Regulatory Risk 
>> >Assessment"  (Graham et al. 1996).  The panel was comprised of an 
>> >international group (mostly from the USA, however) of well-respected, 
>> >middle-of-the-road risk assessors from universities, governments, and 
>> >industry groups.  
>> >
>> >Steve Wing and colleagues have published a reanalysis of TMI health 
>> >effects data (Wing et al. 1997).  Both the new Wing study and the work 
>> >of B.L. Cohen (Cohen 1995) are in a category of descriptive 
>> >epidemiology, as opposed to analytical epidemiology.  
>> >
>> >Whether descriptive or analytic, virtually all occupational and 
>> >environmental epidemiology studies are "observational" as opposed to 
>> >"experimental" (a.k.a. clinical or interventional) studies.  Since human 
>> >experimentation, outside of closely supervised clinical trials, is out 
>> >of the question, we are left with observational study designs which, 
>> >unfortunately, are not the most cogent designs because of uncontrolled 
>> >factors.  Neither the Wing TMI study nor Cohen's study are 
>> >"experiments," but rather compilations and analyses of whatever data are 
>> >available.
>> >
>> >If you are upset by Wing yet celebrate Cohen, I ask that you examine why 
>> >descriptive studies are compelling in one case and not in the other.  To 
>> >me, the bottom line is that neither have data for individuals, neither 
>> >has meaningful control for confounders and biases, and no amount of 
>> >statistical analysis will change that.  Both fail to meet many of the 
>> >criteria presented by leading risk analysts.
>> >
>> >I am reminded of the brouhaha about Steve Wing and co-workers' earlier 
>> >study of ORNL workers (Wing et al. 1991), which at least was an analytic 
>> >cohort study.  Lest I be branded as being on one side of the the issue 
>> >of radiation risks, I note that my reply to Wing (Strom 1991b) included 
>> >direct criticism of the methods as well as a reminder to consider the 
>> >Bradford Hill criteria (Hill 1965) for interpreting an association as 
>> >causal as reiterated by the Expert Panel (Graham et al. 1996).
>> >
>> >As an illustration of the Bradford Hill criteria, I offer a 
>> >tongue-in-cheek quote from my colleague Dwight Underhill: "In the 
>> >winter, I wear galoshes.  In the winter, I get colds.  Therefore, 
>> >galoshes cause colds."  Association?  22 standard deviations, I'd guess. 
>> >Causation?  Not by criteria I use.
>> >
>> >I must also confess that I do not form my opinions on the basis of books 
>> >published by what National Public Radio calls "the Libertarian Cato 
>> >Institute," which published Steve Milloy's "Junk Science" book.  At the 
>> >associated web site, one finds ecologic studies celebrated if they 
>> >support deregulation, no effects, or hormesis; and denounced if they 
>> >support regulation, or harmful effects of some agent or other.  Again, 
>> >these are not criteria I use to judge the weight of epidemiologic 
>> >evidence.
>> >
>> >References
>> >
>> >Cohen, B.L.  Test of the Linear-No Threshold Theory of Radiation 
>> >Carcinogenesis for Inhaled Radon Decay Products.  Health Physics 
>> >68(2):157-174; 1995.
>> >
>> >Evans, A.S.  Causation and Disease: The Henle-Koch Postulates Revisited. 
>> > Yale Journal of Biology and Medicine 49:175-195; 1976.
>> >
>> >Graham, J.D.; Koo, L.C.; Paustenbach, D.J.; Wynder, E.L.; Ashby, J.; 
>> >Carlo, G.; Cohen, S.M.; Evans, J.S.; Holland, W.; Matanoski, G.M.; 
>> >North, G.W.; Pershagen, G.; Schlesselman, J.J.; Starr, T.B.; Swenberg, 
>> >J.A.; Teta, M.J.; Wichmann, E.; Williams, G.M.; Kelly Jr., W.J.; 
>> >Auchter, T.G.; Landeck, S.; Ploger, W.D.  Principles for Evaluating 
>> >Epidemiologic Data in Regulatory Risk Assessment. Washington, DC: 
>> >Federal Focus, Inc. 1996.
>> >
>> >Hill, A.B.  The Environment and Disease: Association or Causation?  
>> >Proceedings of the Royal Society of Medicine 58:295-300; 1965.
>> >
>> >Rothman, K.J.  Causes.  American Journal of Epidemiology 104(6):587-592; 
>> >1976.
>> >
>> >Strom, D.J.  The Ecologic Fallacy.  Health Physics Society Newsletter 
>> >19(3):13; 1991a.
>> >
>> >Strom, D.J.  A Critique of "Mortality Among Workers at Oak Ridge 
>> >National Laboratory".  Nuclear News 34:67-74; 1991b.
>> >
>> >Strom, D.J.  Radon Study Shows Little Correlation.  Letter.  Health 
>> >Physics 72(3):488-489; 1997.
>> >
>> >Susser, M.W.  What is a cause and how do we know one?  A grammar for 
>> >pragmatic epidemiology.  American Journal of Epidemiology 133:635-648; 
>> >1991.
>> >
>> >U.S.Preventive Services Task Force.  Guide to Clinical Preventive 
>> >Services. Baltimore: Williams & Wilkins; 1989.
>> >
>> >Wing, S.; Shy, C.M.; Wood, J.L.; Wolf, S.; Cragle, D.L.; Frome, E.L.  
>> >Mortality Among Workers at Oak Ridge National Laboratory: Evidence of 
>> >Radiation Effects in Follow-Up Through 1984.  Journal of the American 
>> >Medical Association 265(11):1397-1402; 1991.
>> >
>> >Wing, S.; Richardson, D.; Armstrong, D.; Crawford-Brown, D.J.  A 
>> >Reevaluation of Cancer Incidence Near the Three Mile Island Nuclear 
>> >Plant: The Collision of Evidence and Assumptions.  Environmental Health 
>> >Perspectives 105(1):52-57; 1997.
>> >
>> >
>> >The opinions expressed above are my own, and have not been reviewed or 
>> >approved by Battelle, the Pacific Northwest National Laboratory, or the 
>> >U.S. Department of Energy.
>> >
>> >Daniel J. Strom, Ph.D., CHP
>> >Staff Scientist
>> >Health Protection Department K3-56
>> >Pacific Northwest National Laboratory
>> >Battelle Boulevard, P.O. Box 999
>> >Richland, WA 99352-0999 USA
>> >(509) 375-2626
>> >(509) 375-2019 fax
>> >dj_strom@pnl.gov
>> >
>> >
>> 
>
>
>