title: Cough quality in children: a comparison of subjective vs. bronchoscopic findings.
abstract: BACKGROUND
  Cough is the most common symptom presenting to doctors. The quality of cough (productive or wet vs dry) is used clinically as well as in epidemiology and clinical research. There is however no data on the validity of cough quality descriptors. The study aims were to compare (1) cough quality (wet/dry and brassy/non-brassy) to bronchoscopic findings of secretions and tracheomalacia respectively and, (2) parent's vs clinician's evaluation of the cough quality (wet/dry).
  
  
  METHODS
  Cough quality of children (without a known underlying respiratory disease) undergoing elective bronchoscopy was independently evaluated by clinicians and parents. A 'blinded' clinician scored the secretions seen at bronchoscopy on pre-determined criteria and graded (1 to 6). Kappa (K) statistics was used for agreement, and inter-rater and intra-rater agreement examined on digitally recorded cough. A receiver operating characteristic (ROC) curve was used to determine if cough quality related to amount of airway secretions present at bronchoscopy.
  
  
  RESULTS
  Median age of the 106 children (62 boys, 44 girls) enrolled was 2.6 years (IQR 5.7). Parent's assessment of cough quality (wet/dry) agreed with clinicians' (K = 0.75, 95%CI 0.58-0.93). When compared to bronchoscopy (bronchoscopic secretion grade 4), clinicians' cough assessment had the highest sensitivity (0.75) and specificity (0.79) and were marginally better than parent(s). The area under the ROC curve was 0.85 (95%CI 0.77-0.92). Intra-observer (K = 1.0) and inter-clinician agreement for wet/dry cough (K = 0.88, 95%CI 0.82-0.94) was very good. Weighted K for inter-rater agreement for bronchoscopic secretion grades was 0.95 (95%CI 0.87-1). Sensitivity and specificity for brassy cough (for tracheomalacia) were 0.57 and 0.81 respectively. K for both intra and inter-observer clinician agreement for brassy cough was 0.79 (95%CI 0.73-0.86).
  
  
  CONCLUSIONS
  Dry and wet cough in children, as determined by clinicians and parents has good clinical validity. Clinicians should however be cognisant that children with dry cough may have minimal to mild airway secretions. Brassy cough determined by respiratory physicians is highly specific for tracheomalacia.
authors.affiliation: Dept of Paediatrics & Child Health, University of Queensland, Australia. annechang@ausdoctors.net
authors.forename: Anne Bernadette
authors.initials: AB
authors.lastname: Chang
authors.forename: Justin Thomas
authors.initials: JT
authors.lastname: Gaffney
authors.forename: Matthew Michael
authors.initials: MM
authors.lastname: Eastburn
authors.forename: Joan
authors.initials: J
authors.lastname: Faoagali
authors.forename: Nancy C
authors.initials: NC
authors.lastname: Cox
authors.forename: Ian Brent
authors.initials: IB
authors.lastname: Masters
mesh_terms: D001315:Australia / Q000453:epidemiology; D001999:Bronchoscopy / Q000706:statistics & numerical data*; D002675:Child, Preschool; D003371:Cough / Q000145:classification* / Q000453:epidemiology / Q000473:pathology*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D015588:Observer Variation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D016037:Single-Blind Method