Utility of cough response during hypertonic histamine challenge in diagnosing asthma

SummaryAirway responses to bronchial provocation tests are traditionally assessed with spirometry which necessitates considerable patient co-operation. It has been shown that coughing during bronchial provocation tests is related to the degree of bronchoconstriction which, in turn, is independent of patient co-operation. The aim of the present study was to evaluate the utility of coughing induced by the hypertonic histamine challenge in the differential diagnosis of asthma in a clinically relevant patient population.The study population consisted of 25 healthy volunteers, 30 asthmatics, and 82 non-asthmatic subjects with respiratory symptoms due to other diseases. Hypertonic histamine solution was administered with ultrasonic nebuliser with the challenges being videotaped. The cough response was expressed as the cumulative number of coughs divided by the final histamine concentration administered (CCR).The geometric mean (95% CI) of CCR for asthmatics was 302 (166–562) coughs per mg/ml, for the symptomatic controls 29.5 (20.0–43.7) coughs per mg/ml (p<0.001) and for the healthy controls 6.61 (3.02–14.5) (p