Re: Calculation of Risk for Down
From: art fougner, md (evsono@pipeline.com)
Sat Feb 24 14:41:13 2001
David -
in your opinion then, you would favor combining serum risks, age risks,
and sonar risks? or would one trump the other, eg age 42 would be enough
to warrant karyotype?
thanks
art
At Fri, 23 Feb 2001, D. Nyberg wrote:
>
>There is reasonable evidence to indicate that ultrasound and
>biochemical markers are largely independent. We can review what data is
>available, but I'm sure you'll also see more on this in the future.
>Recall that ultrasound and biochemical markers also are independent in
>the first trimester so this should not be surprising. Although it would
>be preferable to offer a combined ultrasound-biochemical risk (as
>Bahado-Singh has does, and as we will present at the AIUM in a few
>weeks), a simple method is to base the apriori risk on the triple screen
>result (biochemistry plus age). We will need further studies to see how
>accurate that approach is, but for now it seems like a reasonable
>approach to use in practice.
>
>David Nyberg
>
>On Fri, 23 Feb 2001, Ph Coquel wrote:
>
>> Doc Gyneco said::
>>
>> > To alter her triple-screen risk you must be sure about statistical
>> > independance between the serum markers and the hyperechoic bowel marker.
>> >
>> > In my opinion, there is no study in this issue.
>> >
>> > So, you can't modified the triple screen risk.
>> >
>> > And the likelihood ratio could be apply to her age related risk.
>>
>> Yes, but in UOG 2000;16:402-406, Verdin and all analyse the value of the
>> second trimester ultrasound examination among the women whose fetuses were
>> indicated to be at low risk for chromosomal anomalies on the basis of both
>> first trimester nuchal translucency measurement and second trimester
>> biochemical screening
>>
>> LLR for echogenic bowel is 283 (71 -1133) 95% IC with 2 abnormal karyotype
>> for five fetuses at low risk
>>
>> But the study numbers are relatively small (5500 pregnacies) and 3548
>> considered negative after bichemical screening (7 abnormal karyotype in this
>> group)
>> ¨
>> Ph Coquel,MD
>>
>> Annecy, France
>>
>--------------------------------------------------------------------
>David A. Nyberg, M.D !!!!
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art fougner, md
A series of 1000 cases begins with but a single anecdote.
