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Re: Schneeberg Study Criticisms
Thank-you for your open replies. I am glad to hear you are increasing your
Your response brought up some further questions.
1) You said, despite its small size, the overall power of the Schneeberg
study is very high. A comparison of the power of all recent population
studies you can take from our website: Publikationen, "Lembcke, J: Zur Power
der Deutschen Radonstudie (Ost),
>vollständiger Text, 2000"
I understand that you may have power to see high excess risks, because of
the very high radon concentrations in the area. The question remains, how
good is your power to see any possible risks in the area of 150 Bq/m3? What
risk do you base your power calculations on?
2) You said you have "already tried less and other categorizations
with improved results for confidence."
Shouldn't your categorizations be chosen months ahead of your actual
analysis? Is it good science to manipulate the categories around after the
fact in order to get specific findings? I am really not sure why you are
performing analyses while you are still collecting data. I would think you
would want to stay blinded to what you are finding in order to not introduce
any biases into your study. It would good to know now what your final
categories are going to be when you are finished with the collection of your
data. The justifications for the categories can be made now and the
categories should not change.
3) I also have some questions about the comparability of your controls. Can
you explain why there is a significant difference in the radon
concentrations between your 2 control groups?
I look forward to your response after Easter about retropective cases and
your ability to estimate their radon in addition to getting accurate
biographical information. Am I correct in my reading of your paper that all
your cases were deceased and that all your information about them came from
family members and friends? I look forward to your explanation on the
comparability between the retrospective cases and their matched controls.
Thanks, Jim Nelson
>From: firstname.lastname@example.org (Dr. Karl Martin)
>CC: email@example.com, firstname.lastname@example.org
>Subject: Schneeberg Study Criticisms
>Date: Sun, 15 Apr 2001 13:32:20 +0200
>your three problems with the study became obviously some more when you
>them. They are worth, together with your proposals, to be discussed.
>1. Number of cases
>You are right, the number of cases is very small. Therefore we are working
>include in the study more female cases and additionally non-smoking male
>This will help to increase the confidence and narrow the CI. We do not
>fundamental change in the risk estimate.
HOW DO YOU KNOW THIS KARL?
>The risk analysis was made with two extreme approaches: table 17 with raw
>(14 smokers and all types of histology and cases without confirmed
>included) and table 18 with stratified data including only cases
>strictest demands in data quality (validated non-smokers only and lung
>histologic confirmed). Only for table 18 your criticism regarding number of
>cases "6 or less" applies.
>Both curves (raw and stratified data) are quite similar, confirming that
>lung cancer risk for non-smokers from radon is higher than that from
>that the results from the most demanding data quality is in accordance with
>raw data (only 14 cases smokers, 22%).
>We did not pretend to have found a threshold - it was not our intention. In
>"Results from the research", part "Contribution to the discussion of LNT",
>was stated: "The Schneeberg Study is considered by its authors as a
>to the growing body of scientific evidence that the LNT model might not be
>in the low dose range, and that further research is needed". When a "safe
>threshold" is mentioned, than only in the sense, that in the low exposure
>categories no health risk could be established. We avoided therefore the
>expression "certain threshold". Maybe this was not an excact enough wording
>express what was really meant. Sorry.
>Despite its small size the overall power of the Schneeberg study is very
>comparison of the power of all recent population studies you can take from
>website: Publikationen, "Lembcke, J: Zur Power der Deutschen Radonstudie
>vollständiger Text, 2000". This paper is in German but you can read easily
>4, adjusted OR, smokers among controls known, mobility considered.
>2. Retrospective cases
>Response after Easter.
>3. Death certificates
>The data collection for cases and controls is mainly based on data from the
>cancer registry (1952 to 1989). During this period it was mandatory for
>doctor to notify the local cancer registry by standardised forms. From 1990
>to 1995 due to reunification of Germany, mandatory notification of cancer
>stopped. Nowadays the cancer registry continues on the Federal State level
>Saxony, including the study area Schneeberg, and mandatory notification of
>cancer cases is introduced again. Only cases from 1990 on are collected
>death certificates. Primary cancers only were eligible for inclusion in the
>4. Exposure categories
>It looks as if the exposure categories were chosen arbitrarily. The reason
>this is, that other population studies, prior to the Schneeberg Study, have
>chosen this categorisation (mostly up to >140 Bq/m³). We intend to do a
>reanalysis of our data. We have already tried less and other
>with improved results for confidence.
>Your summarising remark, that a positive trend for indoor radon exposure
>lung cancer was found is correct, when applied to high exposure levels.
>questioned is whether low radon levels such as found in most houses may
>the lung cancer risk. An other conclusion from the Schneeberg study is that
>confounder smoking cannot be controlled invalidating risk estimates for
>cancer from indoor radon with case-control studies with mainly smokers
>cases and controls. Consequently, we should focus future studies on
>in highly exposed populations only with a wide range of exposure for
>from 50 Bq/m³ to > 3.000 Bq/m³.
>A first attempt with HP has failed. It will be repeated after some
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