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

Azithromycin is beneficial in a multitude of respiratory diseases; however, its effects on both subjective and objective measures of cough have been less extensively studied. Traditional 24-h cough counting assessments are highly variable, potentially underestimating the antitussive effect of therapeutics.

Patients with asthma, COPD, interstitial lung disease and refractory chronic cough who reported cough as the predominant symptom were continuously monitored using a smart watch equipped with Hyfe cough detection software. 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 visual analogue scale diary. Cough data were analysed using the novel cough metrics "relief of cough" and "cough density".

30 participants with a broad range of respiratory diseases were recruited; 80% (n=24) had satisfactory usage of the cough monitor (>12 h·day^-1 for 90% of study days). There was a significant reduction in the geometric mean of coughs per hour from pretreatment baseline to follow-up at week 4 (11.4 versus 7.5 coughs·h^-1, 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.

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.