Serum IgE and eosinophil count in allergic rhinitis--analysis using a modified Bayes' theorem

Area of Science:

• Allergy and Immunology
• Clinical Diagnostics
• Biostatistics

Background:

• Allergic rhinitis diagnosis often relies on clinical presentation and skin testing.
• Establishing objective laboratory thresholds for diagnostic markers is crucial.
• Previous data on specific IgE and eosinophil count thresholds for atopy prediction in rhinitis is variable.

Purpose of the Study:

• To apply probability theory to define threshold values for total serum IgE and eosinophil counts.
• To establish thresholds that support a diagnosis of allergic rhinitis.
• To compare derived thresholds with existing published data.

Main Methods:

• A prospective study involving 125 rhinitis patients at the West Los Angeles VA Medical Center.
• Utilized a modified version of Bayes' theorem to calculate posttest probabilities.
• Included allergy consultation and immediate hypersensitivity skin testing for all participants.

Main Results:

• 89 out of 125 patients (71.2%) were identified as atopic via skin testing.
• IgE thresholds >140 IU/ml and eosinophil counts >80 cells/ml showed high probability of predicting atopy.
• Serum IgE levels demonstrated a greater influence on atopy prediction than eosinophil counts.

Conclusions:

• IgE levels >140 IU/ml and eosinophil counts >80 cells/ml are likely indicators of atopic etiology in rhinitis patients.
• This probabilistic model can assist in evaluating patients for diagnostic skin testing.
• The findings may inform decisions regarding allergy-modifying treatments.