Background: Routine qualification for specific immunotherapy (SIT) is based on clinical history and skin prick tests (SPT) or specific IgE (sIgE). In cases of discordance between these two, basophil activation test (BAT) may be decisive. The aim of the present study was to determine the specificity and sensitivity of BAT, sIgE, and SPT, and to analyse cases, in which clinical data and SPT alone would result in wrongful qualification for SIT.
Patients and methods: BAT results and sIgE levels to Dermatophagoides pteronyssinus (Dp) and Dermatophagoides farinae (Df) were determined in 52 pediatric patients qualified for SIT based on clinical history and positive SPT. The group included 21 children qualified for SIT with birch or timothy grass, used as reference for specificity and sensitivity calculations for BAT, sIgE and SPT.
Result: The sensitivity and specificity of BAT, using SPT as "gold standard" was 96.9% and 88.9% for Dp, and 89.3% and 100% for Df, respectively and the sensitivity and specificity of sIgE were 89.7%, 88.9% for Dp, and 92.9% and 94.4% for Df. When using BAT as "gold standard", the sensitivity and specificity of SPT was 90% and 90.5% for Dp, 92% and 84,6% for Df, and these indices for sIgE were 87.1% and 90.5% for Dp, 100% and 87.5% for Df. BAT did not confirm the initial qualification for SIT in 2 patients, revealing an unspecific basophil activation. Negative nasal provocation test ultimately confirmed the false-positive SPT, which could be explained by the co-existence of urticaria in those children. In further 2 children qualified for SIT with timothy and birch, BAT revealed lack of reactivity to respective allergens. Altogether BAT helped in avoiding unnecessary SIT in 4 out of 52 children (7.7%).
Conclusions: In most cases, SPT, sIgE and BAT provide comparable information, however, SPT results care is advised in patients with co-existing urticaria. BAT is useful in verifying the actual relevance of allergens selected for SIT and helps in avoiding long-lasting, arduous, costly, and ineffective immunotherapy of wrongly qualified cases.