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I am new to the list and so perhaps this has been discussed before:
 
I reviewed the Expert Files and the Diagnostic Test Files in the Archives.
 
In the 2nd Qtr 96 there is a discussion of the blood tests as there is in
the diagnostic tests.
 
My question is this.  If you take a ratio of 1:250 for celiacs to
non-celiacs in the United States, and if you use the figures for
specificity and sensitivity from the tables in the digests cited above, I
don't understand how the predictive value for testing positive on all
three serological blood tests is so high.
 
For example, with a population of 10,000 I figured just on the EMA test
that 38.8 people would test positive who had the disease and 199.2 would
test positive who didn't have the disease....
 
I tried to figure out the conditional probability of testing postive
given you don't have the disease (a probablity not cited in the literature).
This is assuming you test positive on all three serological blood tests.
 
If anyone can enlighten me I would be thrilled.
 
My daughter has apparently tested positive (she is 8 yrs old) and the
physicians do not think it necessary to do a biopsy.
 
She doesn't seem to have a severe case, just bloated tummy, frequent
stomachaches and diarrhea.
 
TIA
 
 
Melissa Roberts
E-Mail: [log in to unmask]                   Albuquerque, NM