Assessment of allergen-induced respiratory hyperresponsiveness before the prescription of a specific immunotherapy

BACKGROUND: Asymptomatic sensitization is a frequent condition that must be considered before the indication of allergic-specific immunotherapy. OBJECTIVE: The aim of this study was to appreciate and correlate the local and spirometric changes elicited by the allergen-specific nasal provocation test (NPT) to define practical and feasible guidelines for the allergist/immunologist to demonstrate specific respiratory hyperresponsiveness before the indication of allergic-specific immunotherapy. METHODS: A total of 172 subjects (children and adults) with a diagnosis of allergic rhinitis were submitted to flow-volume spirometry immediately before and after the NPT performed with Dermatophagoides antigens. The differences between the pre- and postspirometric estimated values of peak expiratory flow rate (PEF(dif%)), forced expiratory volume in 1 second (FEV(1dif%)), and forced vital capacity (FVC(dif%)) were correlated with the results of the nasal provocation test symptom score (NPT-SS). RESULTS: There were 119 subjects (69%) with NPT-SS > 2. Among these patients who were reactive, the mean NPT-SS was 6.3. The Spearman's correlation between PEF(dif%) and NPT-SS was r = −0.44 (p = 0.01); the Spearman's correlation between FEV(1dif%) and NPT-SS was r = −0.22 (p = 0.01), and the Spearman's correlation between FVC(dif%) and NPT-SS was r = −0.21 (p = 0.04). CONCLUSION: The combined utilization of the allergen-specific NPT-SS with the spirometry (or PEF meter) is a safe methodology to evaluate allergen-specific nasal and bronchial hyperresponsiveness (which sometimes acts as a bronchial provocation test) in patients with allergic rhinitis and asthma due to hypersensitivity who are candidates for allergen-specific immunotherapy.