Allergic rhinitis with or without concomitant asthma: difference in perception of dyspnoea and levels of fractional exhaled nitric oxide

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Abstract
Background/aim Allergic rhinitis (AR) is a risk factor for developing clinical asthma. Moreover, AR is often associated with bronchial hyper‐responsiveness (BHR). The aim of the present study was to investigate whether patients with AR and asthma differed from AR with or without BHR in degree of perception of dyspnoea and airway inflammation, measured as fractionated exhaled nitric oxide (NO). Materials Twenty‐nine patients with seasonal AR (timothy) were investigated with metacholine challenge test. Fourteen healthy non‐reactive subjects served as controls. Methods (1) Metacholine challenge test, cut‐off value forced expiratory volume in 1 s (FEV1) PD20 2000 μg. Slope value for metacholine was calculated as %fall in FEV1/mol metacholine. Dyspnoea during challenge was measured with a 10‐graded modified Borg score. (2) Measurement of fractional‐exhaled nitric oxide (FENO) at flow rate 50 mL/s. Results Eighteen patients reported AR only, without asthma symptoms, and 12 (67%) were BHR. Eleven subjects had both rhinitis and asthma symptoms. Patients with rhinitis and asthma reported significantly more dyspnoea per percent fall in FEV1 compared with those with rhinitis and BHR. Moreover, those with rhinitis and asthma had significantly higher NO values compared with those with rhinitis and BHR. Conclusion The difference between rhinitis patients with or without asthma symptoms seems to be mainly a question of perception of dyspnoea. However, FENO measurement indicates that dyspnoea may also be associated with increased inflammatory activity in the peripheral airways.