Effect of Ivacaftor on Objective and Subjective Measures of Cough in Patients with Cystic Fibrosis

BACKGROUND AND OBJECTIVES Cough is a major symptom in cystic fibrosis. Ivacaftor is a novel drug which targets the G551D mutation and has been demonstrated to improve lung function and weight in the long term. It also improves symptoms of extra-oesophageal reflux. We wanted to evaluate the effect of ivacaftor on cough in cystic fibrosis. METHODS In two patients with cystic fibrosis the Hull Airway Reflux Questionnaire (HARQ) was completed and objective cough counts were measured prior to and within 4 weeks after initiation of treatment with ivacaftor. Spirometry was also undertaken and weight checked at these time frames. RESULTS In the first patient the HARQ score decreased from 29 to 11 and objective cough counts from 29 to 9 cough events per hour. Similarly in the second patient the HARQ score decreased from 13 to 9 and objective cough count from 76 to 5 cough events per hour. There was no significant change in spirometric parameters or weight. CONCLUSION We have observed early subjective and objective improvement in cough measures on treatment with ivacaftor. We suggest that this improvement could be attributed to improvement of gastro-intestinal function and that cough metrics could be used as early and accurate end points of drug efficacy.