Measuring the effect of azithromycin in chronic respiratory disease using continuous cough monitoring: an open-label exploratory trial

Background Azithromycin is beneficial in a multitude of respiratory diseases, however, its effect on both subjective and objective measures of cough has been less extensively studied. Traditional 24-hour cough counting assessments have been shown to be highly variable, potentially underestimating the antitussive effect of therapeutics. Methods Patients with asthma, COPD, ILD, and refractory chronic cough who reported cough as predominant symptom were continuously monitored with the Hyfe® Cough Watch. Patients were monitored 1 week prior to and 4 weeks after commencing azithromycin. Participants were also assessed using patient reported outcome measures and a 4-week daily cough VAS diary. Cough data were analysed using the novel cough metrics ‘relief-of-cough’ and “cough density”. Results 30 participants with a broad range of respiratory diseases were recruited, 80% (n=24) had satisfactory usage of the cough monitor (>12 h per day for 90% of study days). There was a significant reduction in the geometric mean of coughs/hr from pre-treatment baseline to follow-up at week 4 (11.4 versus 7.5, p=0.026). This reduction was observed after 1 week and cough counts reduced progressively from week 1 to week 4. Of the 24 participants who had adequate cough monitoring 29% (n=7) had a >50% reduction in cough frequency. The mean proportion of time that participants had “relief-of-cough” improved between baseline and follow-up (74% versus 81%, p<0.001). There was no significant difference in “cough density’ metric (47.5 versus 42.8, p=0.069). Significant improvements were observed in all patient reported outcomes. Conclusion This is the first study to assess the antitussive effect of a drug using continuous cough monitoring. Further trials should use this method of cough assessment to obtain a more granular assessment of cough in airways diseases.