title: Objective measurement of cough in otherwise healthy volunteers with acute cough.
abstract: 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<0.001). Repeatability was higher for objective cough frequency (intra-class correlation coefficient (ICC)=0.94, p<0.001) than reported cough frequency (daytime VAS ICC=0.784, p<0.001). Crossover/parallel studies require <15 and <41 subjects per arm to detect a 50% reduction in cough frequency with 90% power, respectively. Acute cough frequency is highly repeatable over any 48-h period, allowing small sample sizes to be used when investigating the effectiveness of novel anti-tussives.
authors: The University of Manchester, University Hospital of South Manchester, Southmoor Rd., Manchester, UK.
authors: Kanchan
authors: K
authors: Sunger
authors: William
authors: W
authors: Powley
authors: Angela
authors: A
authors: Kelsall
authors: Helen
authors: H
authors: Sumner
authors: Robert
authors: R
authors: Murdoch
authors: Jaclyn A
authors: JA
authors: Smith
mesh_terms: D000328:Adult; D000996:Antitussive Agents / Q000627:therapeutic use; D003371:Cough / Q000175:diagnosis*; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D008297:Male; D010919:Placebos; D015203:Reproducibility of Results; D012107:Research Design; D012129:Respiratory Function Tests; D012141:Respiratory Tract Infections / Q000175:diagnosis*; D014777:Virus Diseases / Q000175:diagnosis; D055815:Young Adult
chemical_list: D000996:Antitussive Agents; D010919:Placebos