A novel approach to the analysis of ambulatory 24hr cough monitoring data

Abstract

The primary endpoint in many cough studies is 24 hour objective cough counting. When this is compared to our Patient Reported Outcomes (PROs) such as a Visual Analogue Scale (VAS) or cough diary data then a correlation of approxiamately 60% is observed. This suggests that cough counting does not reflect the full patient experience. We hypothesised that periods free from cough maybe a more accurate reflection of the patients perceived improvement in cough. The treatment of cystic fibrosis has been radically changed by the introduction of modulator therapy. We undertook 24-hour cough monitoring in patients prior to and 1 month post initiation of Kaftrio, utilising a semi-automated system for analysis (gift of Professor Birring). Total 24hr cough counts, mean hourly cough counts/24hrs and cough free hours were analysed in 14 patients (5 female, 9 male; mean age 31 years). Analysis revealed cough free hours/24hrs prior to treatment ranged from 0-14 (mean 7.2) which significantly improved, along with all other parameters measured, to a range of 7-19 (mean 13.8) hours cough free post treatment (p<0.01). These results suggest that the improvement in time free of cough is a sensitive index of drug efficacy and maybe more representative of the true patient perception of cough improvement.