Cohen's questions

[epirad@mchsi.com]

Dr. Cohen, You wrote that to your knowledge, there have been no publications

contesting your data. 



You either have not read or have forgotten these papers to name a few:



Field RW, Smith BJ, Lynch CF. Cohen's paradox. Health Physics. 77(3): 328-9, 

Sep 1999.



Smith B J;Field R W;Lynch C F. Residential 222Rn exposure and lung cancer: 

testing the linear no-threshold theory with ecologic data. Health Physics. 75

(1): 11-7, Jul 1998.



Field, R.W., Smith, B.J. and Lynch, C.F.. Ecologic Bias Revisited, A Rejoinder 

to Cohen’s Response to Residential radon-222 exposure and lung cancer: testing 

the linear no-threshold theory with ecologic data. Health Physics. 75(1): 31-

33, 1998.



In fact, Dr. Puskin referenced one of these papers pointing out his concern 

with some of your smoking data, which was further reinforced by his finding.  



----------------------------

Dr. Cohenn stated, My lung cancer data are from National Center for Health

 Statistics. If those data are no good, why are they collected? 



In part they are collected because of ease of collection.  They were never 

intended for use to test the LNT or to use to "treat" confounding. However, my 

point was that the SEER data is more reliable and it is in very poor agreement 

with the data you use.  



Consider this finding:



Arch Intern Med. 2001 Jan 22;161(2):277-84.    

  

Problems with proper completion and accuracy of the cause-of-death statement.



Smith Sehdev AE, Hutchins GM.



Department of Pathology, The Johns Hopkins Hospital, 600 N Wolfe St, Baltimore, 

MD 21287-6901, USA.



BACKGROUND: Mortality statistics are largely based on death certificates, so it 

is important that the data on the death certificate is accurate. At our 

institution, clinicians complete cause-of-death statements (CODs) prior to 

autopsy. Since May 1995, separate CODs have been included in autopsy face 

sheets. METHODS: Clinical and autopsy-based CODs filled out separately on 494 

cases between June 1995 and February 1997 were compared for proper reporting 

and accuracy using the published guidelines and definitions of immediate, 

intermediate, and underlying causes of death put forth by the College of 

American Pathologists and the National Center for Health Statistics. 

RESULTS: Of the 494 death certificates, 204 (41%) contained improperly 

completed CODs. Of these, 49 (24%) contained major discrepancies between 

clinicians' and pathologists' CODs. Of the 494 death certificates, 290 (59%) 

had properly completed CODs. Of the 290 properly completed CODs, 141 (49%) 

contained disagreements: 73 (52%) on underlying CODs; 44 (31%) on immediate 

CODs; and 47 (33%) on other significant conditions (part II). CONCLUSIONS: The 

reliability and accuracy of CODs remain a significant problem. Despite its 

limitations, the autopsy remains the best standard against which to judge 

premortem diagnoses. The CODs of the death certificate may be improved if death 

certificates are completed in conjunction with the postmortem examination and 

amended when the autopsy findings show a discrepancy.



What is your response to this study?

-----

Dr. Cohen states that, the issue of measuring radon now to explain lung cancers

presumably due to radon exposures many years ago is present also in essentially 

all case-control studies. 



Please understand that non differential radon exposure misclassification in a 

case-control study lowers the risk estimates to no association, but in an 

ecologic study can produce unbounded bias in a negative or positive direction.  

 

Dr. Cohen states, "My very extensive studies have shown that nothing except 

urban-rural differences correlate strongly with radon urban-rural differences 

correlate strongly with radon".  



Perhaps you need to more concerned with what correlates with smoking such as 

urban/rural differences since that is driving the majority of the risk versus 

effect.  I presented a potential way for you to perform the analyses to test 

the plausibility of my suggestion (using a Monte Carlo Analyses or a 

Sensitivity Analyses), now the rest is up to you. 





Sincerely, Bill Field

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