Determination of total and specific IgE using UNICAP 100: comparative study with the CAP system.

The methods of serum determination of specific IgE to different allergens have showed lower diagnostic sensitivity than the alternative in vivo methods, the skin tests. The CAP system from Pharmacia, owing to its solid phase, has ameliorated this disadvantage, showing in various studies greater diagnostic sensitivity than the classic RAST, without affecting specificity. However, this system is still semi-automatic and requires daily calibration. UNICAP 100 is a completely automatic autoanalyser for total IgE, specific IgE and Eosinophil Cationic Protein, which combines the high sensitivity of the CAP system with complete automation and monthly calibration. The aim of the present study is to assess the practicality and reliability of UNICAP 100, when compared to the CAP System, for the determination of total IgE and specific IgE, as well as the sensitivity and diagnostic specificity; using as a reference skin tests in 150 paediatric patients. The coefficients of variation in the study of intraseries imprecision ranged between 2.1% and 3.6% for total IgE and between 2.2% and 5.1% for specific IgE, depending on the allergen and the level studied. The intraseries imprecision ranged between 3.3% and 7.7% for total IgE and between 5.2% and 8.9% for specific IgE. The coefficients of correlation of the study of interchangeability with the results of the CAP System varied between 0.985 and 0.998, all the allergens tested (9) being interchangeable. Finally, the diagnostic sensitivity varied between 70% and 95% and the specificity between 87% and 100%. In conclusion, UNICAP 100 showed results that were interchangeable with the CAP System, noticeably improving the benefits owing to its complete automation and its calibration system.