Re: R: Calculation of Risk for Down
From: art fougner, md (evsono@pipeline.com)
Tue Feb 27 15:14:53 2001
Terry -
am eagerly awaiting the data from St. George's using ultrasound alone
as the aneuploidy screen - NO serum screen.
art
At Tue, 27 Feb 2001, Terry J DuBose wrote:
>
>Dr. Corda, I find your comments very interesting... you really should
>publish this data more formally. Of course, having it here will benefit
>many. I love it when sonography shows up well in comparison to other,
>more established tests.
>
>Thanks for your support and participation.
>
>Thanks Terry J. DuBose, M.S., RDMS, APS
>Little Rock, Arkasnas USA
>-----------------
>At Mon, 26 Feb 2001, Andrea Corda wrote:
>-----------------
>-----------------
>-----------------
>>
>-----------------
>>A couple of years ago I used to repeat the triple test on my patients
>-----------------
>>whenever the results were somehow "altered" and to my surprise I had to see
>-----------------
>>that the risk varied from one week to another,in the same patient,from,say
>>1:249 to 1:2850 and ever since I collected,just for the sake of it,a series
>>of these "crazy" triple tests.
>>The fact is that they scare the patient to the bone,and as soon as they get
>>the result,they want to perform an amnio just to be reassured.
>>Of course this way of doing things plays in favour of those who want to
>>perform such procedures and earn in consequence-money and credit-because
>>they say that the triple test is the "only" valid one.
>>Ever since,I perform the NT test according to Nicolaides' rules and I do it
>>between the 12th and the 14th week because at that particular time I'm
>>allowed to see clearly-transvaginally-the cardiac structures and the great
>>vessels.(I'm not mentioning the reminder of the fetus' anatomy because cela
>>va sans dire-the heart is a far more important structure when dealing with
>>chromosomal anomalies than any other and i don't want to think that seeing a
>>myelomeningocele or an absent arm or whatever gross anatomy defect is a
>>difficult job nowadays).I tend to give the due importance to the so-called
>>mild signs of aneuploidy-EIF,Hyperechogenic bowel,dilated renal pelvis
>>etc-and double the risk obtained by NT whenever I find one.
>>This method allowed me to recognize a T21 with normal NT and double EIF at
>>14 weeks (not to mention the fact that she had-of course-a "normal" result
>>of her triple test that was performed just before the amnio and just "for
>>the sake of it"
>>Regards
>>Andrea Corda MD
>>>----- Original Message -----
>>From: Richard M. Roberts <gene@vol.com>
>>To: Multiple recipients of list ULTRASOUND
>><ultrasound@mail.medispecialty.com>
>>Sent: Sunday, February 25, 2001 10:04 PM
>>Subject: Re: Calculation of Risk for Down
>>
>>>Here is my view on this subject. The biochemical markers are screening
>>>tests, not diagnostic tests, and the way they are reported in the US is
>>>atrocious and statistically fallacious. Genetic counseling is also
>>>corrupted by the way these results are reported, and I have been just as
>>>guilty as everyone else in utilizing statistically invalid results to
>>>inappropriately scare the pants off or falsely reassure the patient
>>>based on the foolish reportage of the laboratory providing the
>>>biochemical risk. It is high time for us all to realize that the the
>>>emperor of biochemical screening has no clothes.
>>>
>>>Lets analyze this case:
>>>Biochemical results --a 35 year old...triple screen risk 1:7600, noted
>>>by Joseph A Worrall, MD RDMS. Does the 1:7600 have any real meaning,
>>>i.e. her risk is actually 1:7600? NO. What is the real meaning of this
>>>figure (which is the same as saying, what should be disclosed to the
>>>patient)? First of all, the lab may not make it clear that this is a
>>>mid-gestational risk, not the risk AT DELIVERY. They should (but don't)
>>>provide both. Would anyone care to claim that providing a risk at
>>>midgeststion and not comparing it to the risk at end of gestation (about
>>>1/4 less) would be regarded as inappropriate by any sentient pregnant
>>>woman? This is a 35-year old woman. Women 34 or older with negative
>>>biochemical screens are at reduced risk, BUT the patient should be
>>>informed that 10% to 15% of all infants with Down syndrome will be
>>>detectd AT BIRTH, because the sreening test is not a diagnostic test,
>>>and has a high rate of falsely negative results. That is the position
>>>of the American College of Medical Genetics.
>>>http://www.faseb.org/genetics/acmg/pol-15.htm
>>>I don't agree with the blanket statement of the ACMG that 2nd trimester
>>>biochemical screening should not be offered to women older than 34, but
>>>I most definitely believe that any woman that age MUST have full
>>>disclosre of the inaccuracy of the testing, so that she may make an
>>>informed decision. In order for her to make that decision, she must
>>>have a complete explanation of the natural history of an individual
>>>affected with Down syndrome (1/3 develop Alzheimers), and she should be
>>>informed that if she declines amniocentesis, she is going from a 100%
>>>detection rate to an 85-90% detection rate. If she divorces, I have yet
>>>to hear of a man who has sued for custody of a severely handicapped
>>>child. Who should make the informed decision with regard to whether or
>>>not to have an amnio? THE PATIENT. Does 1:7600 have any other real
>>>accuracy other than placing her risk under that of a 35-year old? NO.
>>>There are no published data to say otherwise. I know of no other test
>>>in clinical medicine which is presented as fact, without confidence
>>>limits, and thus providing an inappropriate sense of reality as to
>>>resuts, than biochemical risk evaluation in pregnancy. "Your risk is 1
>>>in 7600", no more, no less, it is not 1 in 7599 or one in 7601. Very
>>>reassuring. BUT there is no difference between a biochemical risk
>>>calculation of 1:7600 or 1:279 at midgestation in their real
>>>significance. They both have only one known proven result: if a 35-year
>>>old woman does not have an amniocentesis, then she will go from 100%
>>>detection rate to 85-90% detection rate. We should not be counseling
>>>women with such patently imprecise an inaccurate risk figures. As
>>>Philippe Coquel states, "it is important to know the confidence limits
>>>of the triple screening". Well, we do not, and therefore we should use
>>>them appropriately. We should just state whether the woman is at
>>>"increased risk" (if higher than the usual risk of a 34-year old), or
>>>"decreased risk" if lower. Why have we been kidding ourselves all these
>>>years?
>>>
>>>Now, and ultrasound finding is different. If you repeat a triple
>>>screen, you will obtain a result completely unrelated to the first. As
>>>a screening test, the next try will tend to regress to the norm. An
>>>ultrasound finding, however, if real, is an objective finding which will
>>>be able to be seen by any skilled ultrasonographer. If you look again
>>>in a day, it will still be there (whereas the next day's triple screen
>>>could be normal). So yes, a reasonable analysis predicts that
>>>ultrasonographic findings are independent of statistical biochemical
>>>screening. Why on earth should any of the unusual physical features in
>>>Down syndrome have any influence on biochemical screening? How would a
>>>flat midface, incomplete outfolding of the scapha helix, prominent ears,
>>>inwardly-curing 5th interphalanges, redundant skin over the back of the
>>>neck, relatively short femora and humeri, even duodenal atresia, have
>>>any bearing on the levels of biochemical markers? You are comparing
>>>physical findings to abnormal cellular biochemistry. Can't be done. I
>>>happen to like Nikolaides' division into "hard" and "soft"
>>>ultrasonographic findings, based on outcome of, I believe, over 100.000
>>>successive first and second trimester ultrasounds. He classifies
>>>echogenic bowel as a "hard" sign--which means offering aminocentesis
>>>after explaining the increased risk to an 18-year old, let alone a 35
>>>year old.
>>>
>>>AND DONT REPORT AN INCREASED RISK AS ABNORMAL. IT IS NOT ABNORMAL, IT
>>>IS INCREASED RISK.
>>>
>>>Please pardon my capitalization.
>>>Regards,
>>>Richard (gene)
>>>
>>>>>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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>>>>> !US!
>>>>>
>>>>>--
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>>>>> ............................
>>>>>
>>>>--
>>>>art fougner, md
>>>>
>>>>A series of 1000 cases begins with but a single anecdote.
>>>>
>>>--
>>>Richard M. Roberts, PhD, MD, FACMG
--
art fougner, md
A series of 1000 cases begins with but a single anecdote.
