Diagnosing of bakers' respiratory allergy: Is specific inhalation challenge test essential?

The diagnosis of occupational asthma (OA) and/or rhinitis needs to be confirmed by means of objective methods, because it is followed by important social and financial consequences. The aim of the study was to evaluate sensitivity and specificity of diagnostic methods as skin-prick tests (SPTs) to occupational allergens, evaluation of allergen-specific serum IgE, and nonspecific bronchial hyperreactivity with reference to a specific inhalation challenge test in diagnosing bakers' respiratory allergy due to wheat flour. The study group included 358 bakers suspected of having OA due to wheat flour. They underwent physical examination, SPTs to common and occupational allergens, allergen-specific IgE determination, spirometry, nonspecific bronchial challenge, and specific inhalation test. The sensitivity of SPTs to occupational allergens in recognition of baker's rhinitis was low (47.9%) unlike the estimation of allergen-specific IgE (76.4%), with relatively high specificity (77.4 and 68.3%, respectively). Bronchial hyperreactivity (PC₂₀ < 8 mg/mL) was the most sensitive method, whereas high degree of bronchial hyperreactivity (PC₂₀ < 1 mg/m³) alone or bronchial hyperreactivity (PC₂₀ < 8 mg/m³) combined with the skin reactivity to wheat flour was the most specific method of recognizing OA. Neither SPTs to occupational allergens nor evaluation of serum allergen‐specific IgE alone or combined with nonspecific bronchial hyperreactivity are characterized by sufficient diagnostic accuracy to replace the specific inhalation challenge test. For the establishment of a definite diagnosis of baker's asthma, specific challenge testing with occupational allergens should be performed.