Evaluation of the phadiatop test in the diagnosis of allergic sensitization in a general adult population.

BACKGROUND

Phadiatop is a commercially available qualitative serological test employed for screening of allergic sensitization in patients with suspected allergic diseases.

AIM

The study evaluated the diagnostic accuracy of Phadiatop for the diagnosis of allergic sensitization in a general adult population.

METHODS

A total of 469 subjects from the population of A-Estrada (Spain) were selected by age-stratified random sampling (age range, 18-92 years). Phadiatop test (Uni-CAP method) was performed in serum samples from 465 of these subjects. Skin prick tests to a panel of 13 relevant aeroallergens in the studied area (including mites, pollens, moulds, and animal dander) were employed as the reference diagnostic procedure. Subjects with at least a positive skin prick test (> or =4 mm, n= 120) were considered to have allergic sensitization.

RESULTS

Phadiatop sensitivity was 70.8% (95% CI 61.7-78.6%), specificity 90.7% (95% CI 87.0-93.5%), positive predictive value 72.6% (95% CI 63.5-80.3%), negative predictive value 89.9% (95% CI 86.2-92.8%), global accuracy 85.6% (95% CI 82.0-88.6%), negative likelihood ratio 0.3 (95% CI 0.2-0.4), and positive likelihood ratio 7.6 (95% CI 5.4-10.8). A high proportion of false-positive Phadiatop cases showed (a) increased total serum IgE levels, (b) significant alcohol consumption, and (c) small-sized (below the diagnostic cut-off) wheal reactions on SPT. A high proportion of false-negative Phadiatop cases showed exclusive storage mite sensitization. Sensitivity and positive predictive value of Phadiatop were somewhat higher among individuals with a history of nasal or bronchial symptoms.

CONCLUSIONS

Phadiatop is a valuable tool for the diagnosis of allergic sensitization in a general adult population. However, limitations of the test should be taken into account in similar surveys.