validation of an automated cough detection system in

The sensitivity of the system falls from 91 to 86 % when 6-h validation was performed. BIRRING et al. [1] state that the reduction in sensitivity is most likely due to a more robust measure of true cough frequency used for the 2-h recordings. An alternative explanation is that the 2-h validation is poorly representative of the performance of the device over longer time periods. The data is presented for 24-h recordings on 50 subjects. So where are the data on sensitivity and specificity validated over a full 24 h? Previous publications have manually counted cough over 24-h periods in larger numbers of patients [2]. Furthermore, the title of the paper describes the Leicester Cough Monitor as an automated cough detection system. In fact, operator input is required to classify sounds that might have been wrongly identified as cough events in the first phase. Therefore, the system would be more accurately described as semi-automated. This is now the third publication on the Leicester Cough Monitor without validation beyond 6 h, yet the authors invite others to contact them to use the monitor based on this data. We ask S.S. Birring and co-workers to state candidly whether this device has or has not been validated over 24 h. If it has, can they please provide the missing data on 24-h validation so that we can assess the true accuracy of the Leicester Cough Monitor