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Re: Cohen's Fallacy
Mr. Mohaupt,
They adjusted for smoking using a multi variate analyses, that is correct.
I believe the sample size in the North American pooling will be sufficient
to determine whether or not radon exposure to just never smokers is a risk
or not. My guess is it may be a greater factor since there is no increased
mucous secretions from the smoking to attenuate the alpha particles. The
hypotheses the Iowa Study was testing was whether or not prolonged
residential radon is a problem in females who have developed lung cancer and
have lived in the same home for at least 20 years. Perhaps they can perform
another study on never smokers down the road, but that was not the focus of
their study. I can not convince you of the strenth of multivariate
analyses, that is your personal view and I respect that. Most epidemiologist
(other than Howard who calls himself an epidemiologist) would disagree.
Plus the Iowa inverstigators performed tests for residual confounding and
did not find any.
The German study was positive regardless of the spin you put on it.
Alavanja's study was not of just never smokers, but rather ex smokers and it
lacked power.
Don
>From: Tom Mohaupt <tom.mohaupt@wright.edu>
>To: Rad health <healthrad@hotmail.com>
>CC: RuthWeiner@AOL.COM, muckerheide@MEDIAONE.NET,
>radsafe@list.vanderbilt.edu
>Subject: Re: Cohen's Fallacy
>Date: Mon, 28 Jan 2002 15:36:04 -0500
>
>Mr. Rad Health,
>Ruth suggests that cases with smoking be subtracted from the data. You say
>that that this is what was done with the Iowa study, and I disagree. The
>cases with smokers were not subtracted, but included in the evaluation.
>
>Secondly, you espouse the virtues of a multivariate regression to account
>for smoking and I disagree that this is adequate for radon and lung cancer.
>
>For most cancers other than lung, smoking is not a direct insult to the
>organ in question, i.e., smoking tends to be another confounding factor. In
>lung cancer, smoking directly insults the lung. About 90% of the lung
>cancers would go away if smoking were removed. Smoking deposits hot
>particulates in the lung. It contains enumerable chemical carcinogins.
>Smoking directly changes the physiology of the respiratory system, thus
>hindering the lung from functioning properly. It also deposits a higher
>dose from alpha particles than from radon. Theory suggests that the alpha
>particles from radon induce lung cancer. The dose from smoking is much
>greater than radon, but it is not accounted for in the population-based
>radon studies. It's not a simple confounder and cannot be treated as such.
>Also, many of the radon studies of never-smokers have been negative. If the
>smoking model is correct, the results of studies including smokers and
>never-smokers should agree. Since they don't, I question whether the
>modeling for smoking is correct.
>Tom
>
>Rad health wrote:
> >
> > Ruth's second points:
> >
>
> >
> > >6. Look at whatever relationship exists between radon exposure and the
> > >remaining lung cancers (those that occurred in non-smokers). It is
>also
> > >necessary to look at the secondary smoke exposure in non-smokers, since
> > >secondary smoke is also a pretty well extablished carcinogen.
> >
> > This ignores the interaction between smoking and radon. You get alpha
> > exposure from both radon and tobacco.
> > This part of what Field did and this is likely what will be done in a
> > pooling.
> > >
> > >Maybe this is what Field et al did -- I will have to get their papers
>and
> > >see. But it seems to me that applying some kind of statistical
>correction
> > >for smoking that says, in effect, since the national risk of lung
>cancer
> > >from
> > >smoking is x, and the national (or statewide) fraction of smokers is y,
> > >then
> > >x*y *observed lung cancers are attributable to smoking and the rest to
> > >radon,
> > >doesn't really cut it. All that would tell you is the fraction of
>lung
> > >cancers that MIGHT be attributed to smoking.
> >
> > Regarding a smoking correction - As posted before on this list by
>others,
> > this is the most powerful way to adjust for smoking.
> >
> > Quoting Hosmer and Lemeshow's authoritative book, "Applied Logistic
> > Regression":
> >
> > "One generally considers a multivariate analysis for a more
>comprehensive
> > modeling of the data. One goal of such an analysis is to statistically
> > adjust the estimated effects of each variable in the model for
>differences
> > in the DISTRIBUTION of and associations among the other independent
> > variables. Applying this concept to a multivariate logistic regression
> > model, we may surmise that each estimated coefficient provides an
>estimate
> > of the log odds [of lung cancer] adjusting for all other variables
>[smoking]
> > included in the model."
> >
> > _________________________________________________________________
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>--
>Thomas Mohaupt, M.S., CHP
>University Radiation Safety Officer
>
>104 Health Sciences Bldg
>Wright State University
>Dayton, Ohio 45435
>tom.mohaupt@wright.edu
>(937) 775-2169
>(937) 775-3761 (fax)
>
>"An investment in knowledge gains the best interest." Ben Franklin
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