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

[rkathren@tricity.wsu.edu (Ron L. Kathren)]

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
>
>