Objective measurement of cough in otherwise healthy volunteers with acute cough

Cough is one of the commonest reasons for medical consultation and acute cough associated with upper respiratory tract infections (URTIs) is a global problem. In otherwise healthy volunteers complaining of cough associated with symptoms of URTI, we aimed to assess objective and subjective measures of cough and their repeatability and perform power calculations for the design of future studies to test therapies. We studied 54 otherwise healthy volunteers with acute cough (,3 weeks) (median age 22 yrs (interquartile range 21-26 yrs), 64% female, mean forced expiratory volume in 1 s 97.6±10.5% predicted). All subjects performed 24-h ambulatory cough monitoring and reported cough frequency and severity using visual analogue scales (VAS) on 2 consecutive days. Sample size calculations were performed for crossover and parallel group study designs. Objective cough frequency was high (session 1: geometric mean 12.1 coughs?h-1 (95%CI 9.7- 15.2)) and fell significantly (session 2: 9.0 coughs?h-1 (95%CI 6.9-11.6); p