Re: Glass-Based Radon Measurements (fwd)

[epirad@mchsi.com]

Kai,



The question should be posed to Dr. Lagarde.  He appears 

willing to discuss his findings with you.



Regards, Bill Field

> Dear Kai,

> 

> A quick answer to your mail.

> It is not a question of odds ratio or relative risk. 

> The point is that you have to compute these conditionally on study centers

> and matching factors before combining them. Otherwise, the estimates can be

> severely biased.

> /F.L.

> 

> 

> At 08:13 2002-10-12 -0600, you wrote:

> >Friends,

> >

> >Dr. Lagarde, one of the authors of the Glass-Based Radon-Exposure Assessment

> >and Lung Cancer Risk paper, has kindly commented on my previous posting. His

> >comment is given below. I wonder if any RadSafers would care to comment?

> >

> >Personally, I don't see why one can calculate a relative risks of a combined

> >data set, but not odds ratios. I always thought that, given a relative risk,

> >one can predict what the odds ratio should be. Then the question becomes: If

> >the relative risk is so large, why is the odds ratio so low for high radon

> >exposure categories?

> >

> >Best Regards,

> >Kai

> >

> >----- Original Message -----

> >From: "Frederic Lagarde" <Frederic.Lagarde@imm.ki.se>

> >To: <epirad@mchsi.com>; "Kai Kaletsch" <info@eic.nu>; "RadSafe"

> ><radsafe@list.vanderbilt.edu>

> >Sent: Saturday, October 12, 2002 4:42 AM

> >Subject: Re: Glass-Based Radon Measurements (fwd)

> >

> >

> >> Dear Kai,

> >>

> >> Thank you for your interest in our study and for calculated the odds

> >ratios

> >> from the raw table data.

> >> However such calculations do not make sense when different studies (data

> >> from different centres) are combined, as is presently the case.

> >>

> >>

> >>

> >> Please, transmit a copy of this to previous recipients of your message,

> >and

> >> specify this anywhere else your previous comments appear.

> >>

> >> Sincerely,

> >>

> >> Frederic Lagarde

> >>

> >>

> >>

> >> At 15:25 2002-10-11 +0000, you wrote:

> >> >For your interest.  This was posted on the Radsafe

> >> >Radiaiton list tody.

> >> >----------------------  Forwarded Message:  ---------------------

> >> >From:    Kai Kaletsch <info@eic.nu>

> >> >To:      RadSafe <radsafe@list.vanderbilt.edu>

> >> >Subject: Re: Glass-Based Radon Measurements

> >> >Date:    Thu, 10 Oct 2002 15:16:50 -0600

> >> >

> >> >Friends,

> >> >

> >> >For those interested in Radon, I have calculated the odds ratios from the

> >> >data given in the first 2 rows of Table 4 of the Lagarde et al. paper and

> >> >graphed them. These rows give the number of cases and controls as a

> >function

> >> >of radon concentrations as assessed by air based and surface based

> >> >measurements respectively. The graph can be seen at

> >> >http://members.shaw.ca/eic/odds.pdf

> >> >Also shown on the graph (dashed lines) are the relative risks as reported

> >by

> >> >the authors.

> >> >

> >> >To me at least, it seems that the raw odds tell a different story than

> >the

> >> >RR values.

> >> >

> >> >Please let me know if I made any mistakes in calculating the odds ratios.

> >> >

> >> >Kai

> >> >http://www.eic.nu

> >> >and http://www.gammawatch.com/

> >> >

> >

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