A further evaluation of the clinical use of specific IgE antibody
testing in allergic diseases
Soderstrom L, Kober A, Ahlstedt S, de Groot H, Lange CE, Paganelli
R, Roovers MH, Sastre J. Allergy. 2003 Sep;58(9):921-8.
Abstract
BACKGROUND: The evaluation and interpretation of the
results from blood tests measuring specific immunoglobulin
E (IgE) antibody concentration is currently made using the
dichotomized result from the test despite a quantitative result
is obtained. It has been shown that different levels of IgE
antibodies, assessed by blood test and skin prick test, may
have a relation to presence of symptoms, implying that there
is more information in a quantitative result than in the dichotomous--positive
or negative.
OBJECTIVE: To investigate the clinical utility
of quantification of IgE antibodies in the diagnosis of allergic
patients and whether such procedure has any advantage to
the presently dichotomously used sensitivity and specificity
at a fixed cut-off. METHODS: Data from a previously published
study (R. Paganelli, I.J. Ansoteugi, J. Sastre, C.-E. Lange,
M.H.W.M. Roovers, H. de Groot, N.B. Lindholm, P.W. Ewan,
Allergy, 1998; 53) analysing diagnosis of allergic patients
in four different clinics were re-evaluated. In the original
study consecutive patients with suspected IgE-mediated allergy
had been examined and evaluated according to the clinical
routine at each clinic, using case history, physical examination,
skin tests and laboratory tests, except the test to be evaluated,
and given a "doctors' allergen-specific diagnosis" as
positive or negative. In the present study the relation between "doctors'
allergen-specific diagnosis", expressed as pos/neg,
and the quantitative levels of specific IgE antibody concentration
was analysed using a logistic regression model. This presentation
of results was also compared with the more common characteristics
of sensitivity and specificity, and also with Receiver-operator
characteristics (ROC) curves.
RESULTS: The used logistic
model described the relationship between allergen-specific
diagnosis in each study and the levels of IgE antibodies.
The shape of the curve illustrated the physicians' disposition
for a positive diagnosis in the study, in relation to the
specific IgE antibody level. Differences in the shape of
the curve was found both between allergens within clinics
and between clinics for the same allergen. No association
could be demonstrated between prevalence and shape of the
curve.
CONCLUSIONS: Conventional sensitivity/specificity
figures or ROC concepts only use the qualitative statement
of whether IgE is present or not. A risk assessment using
the quantitative level of IgE antibody to an allergen increases
the utility of the information in clinical context compared
with a qualitative statement of whether IgE is present or
not. The quantification demonstrated the link between specific
IgE antibodies and allergic reactions. The use of objective,
well performing quantitative tests should help improve diagnostic
accuracy and might provide a way for the patient to understand
and manage his or her daily situation and risk for reactions.
Request full article
|
